Article: 224496 of rec.radio.amateur.antenna From: "Mike" References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Subject: Re: FIGHT! FIGHT! FIGHT! Date: Fri, 19 May 2006 19:17:06 +0800 Message-ID: <446da937$0$31531$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Hi. How's about you guys going to Dayton. I'm sure a Tag Fight could be arranged for you all. Two Pin Falls, Two Submissions,or a KO to decide the winner. Maybe if you all meet face to face, you will come to some common agreement, or this thread wii continue ad nausium. Regards Mike. Article: 224497 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 07:19:41 -0500 From: Tom Ring Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: <446db7dd$0$6149$39cecf19@news.twtelecom.net> Richard Clark wrote: > SBS and SRS (Stimulated Raman Scattering) would be suitable search > engine terms (esp. SBS threshold), but I warn you, they lead to > remarkably dense work where only one link in 20 will be accessible. > > 73's > Richard Clark, KB7QHC Thanks. tom K0TAR Article: 224498 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: Running wire close to HF transmit antenna Date: Fri, 19 May 2006 07:36:48 -0500 Message-ID: <126rev7aliu6r5a@corp.supernews.com> References: Ben Jackson wrote: > Let's say I have a free-standing vertical HF antenna transmitting about > 10wa, and I'd like to run wires to something at the tip. Say an > anemometer, or a temperature sensor. What would be the best way to run > the wire up the antenna? If the HF vertical is a pipe, is inside the > best bet? If it's shielded wire next to a solid antenna, will that > affect the radiation pattern of the antenna as a parasitic element? How > much energy at the tip of the antenna will couple into the wire? If the > wire is carrying low-speed digital data (eg for a 1-wire temperature > sensor), how much isolation would it need (choke, AC couple, opto-isolate, > etc) to avoid getting the HF into the digital signal? > > Thanks for any insight! > Hello Ben, If it were me I would find a way to attach it to my roof vents or somewhere else for sure. I'm just real skittish about damaging or false readings from my wxr station because of my rf. Gud luck to you. Butch KF5DE Article: 224499 of rec.radio.amateur.antenna From: "Vito" References: <44636b98$0$22188@dingus.crosslink.net> <446ca625$0$31271@dingus.crosslink.net> <1147971464.030262.29190@j33g2000cwa.googlegroups.com> Subject: Re: Elimination of CW is a loss in the number of ways we can communicate with other. Date: Fri, 19 May 2006 09:39:59 -0400 Message-ID: <446dcabe$0$31914@dingus.crosslink.net> "John S." wrote > Common in machine or human non-radio use? > Human non-radio, like mines and prisons. Article: 224500 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Running wire close to HF transmit antenna References: Message-ID: Date: Fri, 19 May 2006 08:54:01 -0500 Hi Ben Keeping on mind that the data rate going to/from the sensor is very low compared to the RF I *think* they will co-operate. Some thoughts though; - Opto systems have the problem that you need a power supply for the remote end. Using optical fibre is even a more elegant idea than wires but has a high-ish setup cost. You could of course use a IR LED/optotransistor config but as stated the power supply becomes an issue. - You could argue that infrequent TX RF on the antenna even if it affects the sensor (data) can be ignored . This of course depends on what you are using the weather data for. - If the weather data is a DC/AF level only you can allow RF onto the connection wire. Dont bother to try isolating it from the antenna at all. Dont even think of using shielded/coax. This way the effect on the antenna RF use will be small(er). You could get away with a choke/LPF or two at the antenna base, perhaps even with the use of coaxial stubs. (I'd start with a 1/4 wave open coaxial stub between each wire and antenna metalwork ground (ie where the antenna feed coax joins, then a other two further down)) Running the wire on the inside would of course be best for aesthetic and weather damage considerations. - I'd say the effect of a base decoupled wire on the antenna would be neglible next to that of the aneometer or any box at the antenna tip. You would be capacitively loading the antenna at the "worst" place. (assuming a current node like at the tip of a 1/4 wave) ie it would need a retune. Cheers Bob VK2YQA Ben Jackson wrote: > Let's say I have a free-standing vertical HF antenna transmitting about > 10wa, and I'd like to run wires to something at the tip. Article: 224501 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: Date: Fri, 19 May 2006 15:08:11 GMT Richard Clark wrote: > On Thu, 18 May 2006 19:01:58 -0500, Tom Ring > wrote: > > >>I had not heard of the Stokes shift, nor the scattering you mentioned. >>I have some looking up and reading to do. Which, of course, Cecil does >>not, since it's not a Xerox moment. > > > Hi Tom, > > It is pretty exotic, it only relates to radiation, reflection, > refraction, heat, and conduction, topics that are alien to discussion > here in more than TV Guide English it appears. Other difficult > concepts include linearity, coherence, mixing, and gain. > > Stokes shift is the change in frequency due to the non-linear response > of a media to excitation. Typically the excitation is a photon > interacting with a phonon with radiation scattering following. > Injecting an electron (current) can achieve the same end. The effect > of power clamping in fiber optic transmission lines is due to SBS > (Stimulated Brillouin Scattering) threshold. I've been working with > this (Stokes and Anti-Stokes Shift) for some 20 years, and it fails > easy access through a copier. > > The mention came only response to questions of linear response to what > at first glance would be a rather pedestrian transmission line > definition, but Glenn appears to have followed the clown instead of > pursuing his own question - he warned me it may have been pointless. > > SBS and SRS (Stimulated Raman Scattering) would be suitable search > engine terms (esp. SBS threshold), but I warn you, they lead to > remarkably dense work where only one link in 20 will be accessible. > > 73's > Richard Clark, KB7QHC Hi Richard, Stokes' law and the Raman effect can be found in physics texts dealing with quantum mechanics. Georg Joos, in his book _Theoretical Physics_ deals with such things. The reading is dense but the underlying concepts aren't too difficult. The difficulty might lie in understanding how they apply to this discussion. 73, Tom Donaly, KA6RUH Article: 224502 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Running wire close to HF transmit antenna Date: Fri, 19 May 2006 10:53:39 -0500 Message-ID: <23154-446DEA03-1125@storefull-3254.bay.webtv.net> References: Ben Jackson wrote: "Let`s say I have a free-standing vertical HF antenna about 10 wa, and I`d like to run wires to something at the tip." No problem. All the stations I`ve worked in, medium wave and shortwave, had lighted towers. Some also used the towers to support other antennas and devices. Medium wave towers have sampling loops bolted to them for remote current and phase indications. It`s dead simple. Conduit and coax are used to protect wires to devices and other antennas. Conduit and coax are firmly connected, top and bottom, at least, to the tower to shift most of the lightning to the lower-inductance tower. At the bottom across the base insulator, coax is coiled to create a reactance at least 10x the feedpoint impedance of the tower. Similarly, each of the other wires running up the tower for illumination or other purposes is broken at the base for a tower-lighting choke (or Austin transformer) to isolate the RF and lightning. It works like a charm. Best regards, Richard Harrison, KB5WZI Article: 224503 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Fri, 19 May 2006 12:16:53 -0500 Message-ID: <21360-446DFD85-1304@storefull-3257.bay.webtv.net> References: <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> Richard Clark, KB7QHC wrote: "Who. in your estimation, does qualify to discuss it?" If it`s about antennas, I nominate Kraus. If it`s about mathematics, many marhematicians qualify. In algebra, y = mx + b, (the point slope formula), is called linear because it is the graph of a straight line. In the discussion of transmission lines and antennas, you must admit that a uniform transmission line enforces a unique characteristic impedance (a resistance) on energy traveling in either direction. A resistance is linear because Ohm`s law prevails. In free-space, everyone agrees the characteristic impedance is about 377 ohms (a resistance). Kraus says on page 2 of his 1950 edition of "Antennas": "Let the transmission line now be connected to a dipole antenna as in Fig.1-2. The dipole acts as an antenna because it launches a free-space wave. However, it may also be regarded as a section of transmission line (see Sec. 1-2). In addition, it exhibits many of the characteristics of a resonator, since energy reflected from the ends of the dipole gives rise to a standing wave on the antenna. Thus a single device, in this case the dipole, exhibits simutaneously properties characteristic of an antenna, transmission line, and a resonator. Best regards, Richard Harrison, KB5WZI Article: 224504 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> Message-ID: <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> Date: Fri, 19 May 2006 17:47:40 GMT glenn.b.dixon@gmail.com wrote: > By 'simple antenna' I mean an antenna such as a wire dipole without > traps, baluns or other things that could degrade linearity. Seems the easiest measurement of nonlinearity would be the harmonics (if any) generated by the antenna that do not appear in the source signal. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224505 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> Message-ID: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> Date: Fri, 19 May 2006 18:45:19 GMT glenn.b.dixon@gmail.com wrote: > Richard, > > >>>Who, in your estimation, does qualify to discuss it? > > > I would like to hear from someone who has actually measured the > linearity of a simple antenna. I have not done this, so would only be > one guy with an opinion. Plenty of us around. > > By 'simple antenna' I mean an antenna such as a wire dipole without > traps, baluns or other things that could degrade linearity. Since the > linearity of antenna systems in general is in question, the simplest > setup that answers the question would be best. > > In the absence of measurement, can anyone comment on the modelling > software? Does it assume and model a linear system? If so, do we know > of any substantial nonlinear departures from the modelling software? > > Anyone? > > 73, > Glenn AC7ZN > In order to measure something, you have to define what it is, first. Cecil seems to think that in order for a simple dipole to be linear, the current magnitude measured along its length has to be sinusoidal in shape. Actually, though, I have it wrong. What he believes is that since he can't detect any harmonics emanating from a sinusoidally fed dipole, the current along its length must be a sinusoid. Actually, it's supposed to be impossible to represent the current distribution along a dipole using simple mathematical formulas because integral equations have to be solved that are impervious to any solution other than numerical approximation. That's why we need the various forms of NEC. Cecil is wrong for the reason I've given in another post, and, for reasons enumerated by Richard Clark. That won't stop the flow of bellicose posts from him, though. 73, Tom Donaly, KA6RUH Article: 224506 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> Message-ID: Date: Fri, 19 May 2006 18:46:58 GMT Cecil Moore wrote: > glenn.b.dixon@gmail.com wrote: > >> By 'simple antenna' I mean an antenna such as a wire dipole without >> traps, baluns or other things that could degrade linearity. > > > Seems the easiest measurement of nonlinearity would be the > harmonics (if any) generated by the antenna that do not > appear in the source signal. Which wouldn't tell you a single thing about the current distribution along the length of the dipole. 73, Tom Donaly, KA6RUH Article: 224507 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: <7Cobg.29178$4L1.28624@newssvr11.news.prodigy.com> Date: Fri, 19 May 2006 19:01:23 GMT Richard Clark wrote: > On Fri, 19 May 2006 15:08:11 GMT, "Tom Donaly" > wrote: > > >> Stokes' law and the Raman effect can be found in >>physics texts dealing with quantum mechanics. Georg Joos, in >>his book _Theoretical Physics_ deals with such things. The reading >>is dense but the underlying concepts aren't too difficult. The >>difficulty might lie in understanding how they apply to this >>discussion. > > > Hi Tom, > > Certainly Joos would give some entry into the field, but finding work > as accessible outside of a bookstore or library (in other words, > through a search engine) makes for drinking out of a fire hose to > quench a sip's worth of thirst. > > Insofar as HOW this applies, I've spoken to that and Tom shows > interest. That alone goes beyond the typical churning that passes for > discussion. The point is that these underlying concepts are fairly > simple as you imply and they are certainly not remote from the usual > topics of consideration here. What they lack is specifics that relate > to our common applications, and there too I've offered discussion. > However, few seem inspired to travel those paths and that fault can > hardly be laid at my doorstep. > > 73's > Richard Clark, KB7QHC Hi Richard, I didn't intend any criticism. People like Cecil, with home-grown theories, don't ever seem to want things considered in depth. That's understandable from a psychological standpoint, but it isn't any help to the rest of us when some of the things the theory ignores become significant. In the case of antennas, practically everything is significant. 73, Tom Donaly, KA6RUH Article: 224508 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 14:24:07 -0500 From: Tom Ring Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> Message-ID: <446e1b59$0$1004$39cecf19@news.twtelecom.net> Richard Clark wrote: > On Fri, 19 May 2006 15:08:11 GMT, "Tom Donaly" > wrote: > > >> Stokes' law and the Raman effect can be found in >>physics texts dealing with quantum mechanics. Georg Joos, in >>his book _Theoretical Physics_ deals with such things. The reading >>is dense but the underlying concepts aren't too difficult. The >>difficulty might lie in understanding how they apply to this >>discussion. > > > Hi Tom, > > Certainly Joos would give some entry into the field, but finding work > as accessible outside of a bookstore or library (in other words, > through a search engine) makes for drinking out of a fire hose to > quench a sip's worth of thirst. > > Insofar as HOW this applies, I've spoken to that and Tom shows > interest. That alone goes beyond the typical churning that passes for > discussion. The point is that these underlying concepts are fairly > simple as you imply and they are certainly not remote from the usual > topics of consideration here. What they lack is specifics that relate > to our common applications, and there too I've offered discussion. > However, few seem inspired to travel those paths and that fault can > hardly be laid at my doorstep. > > 73's > Richard Clark, KB7QHC And a web search produced a couple very good links out of the first 20. One was a great discussion of problems in long optical fibers, and some relatively simple ways to work around some of them, or at least to mitigate them. tom K0TAR Article: 224509 of rec.radio.amateur.antenna From: "The always Benevolent dbu." Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Fri, 19 May 2006 21:07:17 GMT In article , Dave wrote: > I use a "multi-band center fed doublet" for 80 through 10 meters. It is > fed with 600 ohm open wire tuned feeders. Feeder length is just enough > to get from the tuner to the antenna , about 180 feet. The > tuner/balun are bonded together and connected to electrical neutral. > > No RF in the shack on 80 through 10. Well that's not really true. I'm > sitting in the near field; but, I don't have RF hotspots on anything in > the station at 1KW. > Thanks Dave. I just reconfigured my feedline and shortened it up also re-doing the physical layout. I have used this setup, open wire feed with 126 ft center fed wire for years and have never had a RF feedback problem in the shack. I asked the question because in the process of reconfiguration I consulted several sources which illuminated inconsistencies regarding length. From the responses I received here there does not seem to be any agreement on length and my question was not answered, at least not to my satisfaction. Anyway so far I'm ok with my current setup. 73 Dale, K9VUJ > > > dale.j. wrote: > > > What is the correct way to determine the non-resonant feedline length of > > a multiband doublet using 450 ohm open wire. > > > > tnx > > Dale > > -- "I'm not going to have some reporters pawing through our papers. We are the president." --Hillary Clinton commenting on the release of subpoenaed documents. Article: 224510 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Fri, 19 May 2006 16:01:53 -0500 Message-ID: <23819-446E3241-1372@storefull-3252.bay.webtv.net> References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> Tom Donaly, KA6RUH wrote: "Actually, it`s supposed to be impossible to represent the current distribution along a dipole using simple mathematical formulas because integral equations have to be solved that are impervious to any solution other than numerical approximation." How many places do you attach to pi? First, what is linearity? It is the absence of nonlinearity. Millman and Seely wrote on page 525 of the 1951 edition of "Electronics" (one of my old textbooks): "Because of this nonlinear characteristic of the dynamic curve over the operating range, the wave form of the output wave differs slightly from that of the grid-exciting-voltage waveshape. Distortion of this type is called "nonlinear" or "amplitude" distortion.." All of the antennas I`ve worked with had no noticeable amplitude distortion. They caused no harmonics or mixing products. On page 235 of Kraus` 1950 edition of "Antennas" he sets out to solve Hallen`s equation for current distribution. On page 239, Kraus writes: "It is generally assumed that the current distribution of an infinitesimally thin antenna is sinusoidal, and that the phase is constant over a 1/2-wavelength interval, changing abruptly by 180-degrees between intervals." You can take what Kraus says to the bank. Best regards, Richard Harrison, KB5WZI Article: 224511 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 16:16:42 -0500 From: Tom Ring Subject: Spark 2006 Message-ID: <446e35bc$0$6155$39cecf19@news.twtelecom.net> This is from the Yahoo Live Wire group. I thought some here might be interested in it. tom K0TAR ------------------------------------- Message 8 From: "David H Hatch" n9zrt@arrl.net Date: Wed May 17, 2006 5:26pm(PDT) Subject: Spark gap - Marconi 2006 Hi Live-Wires, With permission, I am posting the following regarding the Marconi 2006 event. -------------- Dan W7OIL has informed the team leader that he is nearly ready with the passive receiver and adaptations for an INC. So today, WI7B is happy to announce they have achieved spark in their 800 KHz rotary spark gap transmitter. They built it from a "Franken'd" Chevy V8 single point distributor and spark coil. With 7 VDC it generates a hefty 0.5 inch spark every 1/500 second (500 Hz rep rate). I've attached photos of the setup and the spark gap, both un-energized and energized. See the progress on the sparkgap here: http://www.wireservices.com/n9zrt/Marconi-06/ Jim NY7T and W7OIL will be adding the LCR circuitry to the spark gap, then move it out the "ranch" to couple to a 375m quarter wave antenna. The group has an STA from the FCC-OET to operate an 800 KHz spark gap transmitter. Callsign WC9XLG. They are legal. Article: 224512 of rec.radio.amateur.antenna Subject: Re: Elimination of CW is a loss in the number of ways we can communicate with other. From: Slow Code References: <1147047627.949564.83230@y43g2000cwc.googlegroups.com> <1147549161.064623.59130@j33g2000cwa.googlegroups.com> <1147586170.894157.292250@d71g2000cwd.googlegroups.com> <38c8.gop.17.1@news.alt.net> <1147832357.964390.122730@i40g2000cwc.googlegroups.com> Message-ID: Date: Fri, 19 May 2006 21:44:49 GMT "Dan/W4NTI" wrote in news:jnOag.3495$y4.724@newsread2.news.pas.earthlink.net: > > "an_old_friend" wrote in message > news:1147832357.964390.122730@i40g2000cwc.googlegroups.com... >> >> Dan/W4NTI wrote: >>> "Not Lloyd II" wrote in message >>> news:38c8.gop.17.1@news.alt.net... >> >>> 4 >> >> this is not a golfign NG dan I would expect you topay attention but you >> insit on disappointing me >>> >>> Dan/W4NTI >> > > Try a spell check you goofball. I don't give a damn if you are dyslexic > or not. That does not preclude you using a spell checker. > > Dan/W4NTI For a spell checker to work good you need to be reasonable close to the word and he ain't even reasonably close. sc Article: 224513 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Fri, 19 May 2006 21:50:35 GMT On Fri, 19 May 2006 21:07:17 GMT, "The always Benevolent dbu." wrote: >inconsistencies regarding length. From the responses I received here >there does not seem to be any agreement on length and my question was >not answered, at least not to my satisfaction. That statement reflects your ability to comprehend what was written by many, rather than what was written. If you expected a specific length as implied by your question "What is the correct way to determine the non-resonant feedline length of a multiband doublet using 450 ohm open wire." then you have been dissapointed. The consistent answer (even if not always well expressed) was that length is not particularly critical, though there may be some length / frequency combinations (that are very dependent on your particular implementation and equipment) that may challenge your ATU. I go along with the advice to use a convenient length of feedline, and if it is challenging to match up with the ATU, then lengthen the feedline a little. Your dissapointment is perhaps caused by your expectation of a specific length. Owen -- Article: 224514 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Fri, 19 May 2006 21:48:38 GMT In article , Dan Richardson <> wrote: > On Fri, 19 May 2006 21:07:17 GMT, "The always Benevolent dbu." > wrote: > > >In article , > > Dave wrote: > > > >> I use a "multi-band center fed doublet" for 80 through 10 meters. It is > >> fed with 600 ohm open wire tuned feeders. Feeder length is just enough > >> to get from the tuner to the antenna , about 180 feet. The > >> tuner/balun are bonded together and connected to electrical neutral. > >> > >> No RF in the shack on 80 through 10. Well that's not really true. I'm > >> sitting in the near field; but, I don't have RF hotspots on anything in > >> the station at 1KW. > >> > > > >Thanks Dave. I just reconfigured my feedline and shortened it up also > >re-doing the physical layout. I have used this setup, open wire feed > >with 126 ft center fed wire for years and have never had a RF feedback > >problem in the shack. I asked the question because in the process of > >reconfiguration I consulted several sources which illuminated > >inconsistencies regarding length. From the responses I received here > >there does not seem to be any agreement on length and my question was > >not answered, at least not to my satisfaction. > > > >Anyway so far I'm ok with my current setup. > > > >73 > >Dale, K9VUJ > > > > It seems to me that we need to remember that radiation coming from the > feed line is cause by common current. If the feed line is balanced (no > common mode current) there will be no radiation from the feed line > regardless of the line's impedance or the feed point impedance. > > Danny, K6MHE > > In my many years I have come to a conclusion that one > useless man is a shame, two is a law firm, and three > or more is a congress. - John Adams > > email: k6mhearrlnet > http://www.k6mhe.com/ I think you have brought up a good point as to the balance of the parallel wires which is self canceling. Maybe I will be able to sleep once again tonight... 73 Dale -- Email: dalej2@mac.com Article: 224515 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: Multiband doublet feedline length Date: Fri, 19 May 2006 22:22:58 -0000 Message-ID: <126sha2opvg86eb@corp.supernews.com> References: In article , The always Benevolent dbu. wrote: >Thanks Dave. I just reconfigured my feedline and shortened it up also >re-doing the physical layout. I have used this setup, open wire feed >with 126 ft center fed wire for years and have never had a RF feedback >problem in the shack. I asked the question because in the process of >reconfiguration I consulted several sources which illuminated >inconsistencies regarding length. From the responses I received here >there does not seem to be any agreement on length and my question was >not answered, at least not to my satisfaction. Well, let me take a crack at it, if I may. First-off: I don't think there's necessarily any single "right" length of feedline, even for a single individual installation. There are certainly a number of "wrong" lengths of feedline: - The classic one - length is too short to reach the rig/transmatch - Too long - feedline drapes on the ground, is looped around near metallic objects, etc. - and there are excessive losses or shock hazards - End-of-feedline impedance on one or more bands is outside the range which can be matched properly. The first two sets of conditions are fairly easy to pin down. :-) The third is, I think, the place where the interesting variables come in. Transmatches aren't all equal, by any means, in the ranges of impedances that they can match (and the matchable impedances don't necessarily form a nice SWR-value circle on the Smith chart!), or the losses in the tuner, or the amount of power that the tuner can handle before it starts to suffer from arcing or balun overheating/saturation. It's likely that in any given installation, there will be multiple lengths of feedline which will allow a match on a particular set of bands. The matches will probably vary in efficiency and Q. Which one will be "best" is, to some extent, a value judgement by the installer and will depend on how the station is going to be operated. For example, if you spend most of your time operating on one or two bands, you might choose a feedline length which allows efficient and fairly low-Q transmatch settings, so that you don't have to adjust the match as often (or as critically) when QSY'ing within a band. Now... how to evaluate the possibilities. Here's one approach which might be worth trying - it's a bunch of work but should let you end up with some useful data. [1] Grab a whole bunch of Smith chart blanks (or get some good Smith chart software, or some other software which lets you handle impedance transformations conveniently). [2] Figure out the minimum and maximum lengths of feedline which would be physically acceptable in your installation... from the shortest which will reach the rig, to the longest which can conveniently be zig-zagged back and forth between feedpoint and rig. Convert these lengths to electrical length (i.e. divide by the feedline's velocity factor, if it's much less than 1.0). [3] For each band, convert the minimum feedline length into wavelengths, modulo 1/2 wavelength (180 degrees). Also, calculate the difference between minimum and maximum feedline lengths in wavelengths. If it's more than 180 degrees, just call it 180. [4] Determine the range of impedances that your transmatch can handle, on each band that you're interested in working. You _may_ be able to use whatever blanket marketing/spec statement the tuner manufacturer provides (e.g. matches any SWR < 10:1, "all impedances from 25 to 1000 ohms", etc.) but it wouldn't hurt to run some tests yourself. You may wish to rule out some impedances even if they're theoretically matchable - e.g. a T-match tuner can often produce a "match" to a near-short-circuit, but the losses in the tuner are so high that it's not worth the bother. [5] For each band, plot the range of matchable impedances on a Smith chart which is normalized to the nominal impedance of your balanced feedline. Use one Smith chart per band to avoid confusion. [6] Choose the length of your doublet, based on space available and/or desired pattern on one or more bands and/or lore and/or any other criteria you desire. [7] For each band, use appropriate tables to determine the feedpoint impedance of the doublet on the band in question. You may wish to calculate several values when the band is fairly wide (e.g. 80 meters). [8] Plot the doublet's feedpoint impedance for each band on that band's Smith chart. [9] Using a compass centered at the Smith chart's origin, rotate the feedpoint impedance "towards generator" by the number of degrees corresponding to the shortest-possible feedline length, as calculated in step 3. Plot this point. [10] Use the compass (centered at the origin) to draw an arc from this point, in the "towards generator" direction, for the number of degrees corresponding to the difference between minimum and maximum feedline lengths. What this should leave you with (we hope) is a chart for each band, which shows where the antenna's feedpoint impedance, transformed by the feedline, falls inside the range of impedances that the transmatch can handle. If the impedance arc comes near the centroid of one of the "We can match this" circle/blob, then the closest-to-centroid point on the arc would correspond to a feedline length which might be a very good one for that band. If the arc doesn't enter a band's matchable circle/blob at all, or just barely enters it, then you may wish to go back to Step 6, pick a different doublet length, and try again. Now, what you can do is take a piece of paper and draw a straight line. Put the minimum feedline length at one end and the maximum at the other. For each band, look at the impedance arc, record the sections at which it's outside of the matchable-impedances blob (measure the number of electrical degrees of rotation from the load), and figure out the feedline lengths that these unmatchable sections correspond do. Use a colored marker to denote these lengths on the straight "minimum to maximum feedline" graph. Borrow color markers or crayons from your kids so that you have one color per band :-) Once you've finished doing this for all of the bands you're interested in, take a look at the straightline graph of feedline length. If you're unlucky, *every* point on that graph will be colored as "not matchable" on one or more of the bands that you care about. If so, you can go back to Step 6 and try a different doublet length, or you can resign yourself to having to switch between two different lengths of feedline when QSYing. If you're not unlucky, there will be at least one range of feedline lengths which can be matched on all bands. If so, I'd suggest choosing a length which causes the impedance arcs you plotted to fall near the centroids of the matchable-impedance areas, on the bands that you use most heavily. The above is very much a manual procedure, requiring at least an hour of calculating and plotting and cussing. There are almost certainly some software tools which can be used to automate and simplify this process. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224516 of rec.radio.amateur.antenna From: Ron Subject: Re: ARS License Numbers Date: 19 May 2006 18:17:15 EDT Message-ID: <446E4561.3090805@yahoo.com> References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> So how many Ham died within that 6 year period. Remember we are a OLDER population. Slow Code wrote: > N2EY@AOL.COM wrote in > news:1148005814.174874.234520@38g2000cwa.googlegroups.com: > > >>These are the numbers of current, unexpired >>amateur radio licenses held by individuals >>on the stated dates, and the percentage of >>the total number of active licenses that >>class contains: >> >>As of May 14, 2000: >> >>Novice - 49,329 (7.3%) >>Technician - 205,394 (30.4%) >>Technician Plus - 128,860 (19.1%) >>General - 112,677 (16.7%) >>Advanced - 99,782 (14.8%) >>Extra - 78,750 (11.7%) >> >>Total Tech/TechPlus - 334,254 (49.5%) >> >>Total General/Advanced/Extra - 291,209 (43.2%) >> >>Total all classes - 674,792 >> >> >>As of May 15, 2006: >> >>Novice - 25,182 (3.8%) [decrease of 24,147] >>Technician - 280,160 (42.6%) [increase of 74,766] >>Technician Plus - 39,130 (6.0%) [decrease of 89,730] >>General - 133,240 (20.2%) [increase of 20,563] >>Advanced - 72,315 (11.0%) [decrease of 27,467] >>Extra - 108,005 (16.4%) [increase of 29,255] >> >>Total Tech/TechPlus - 319,290 (48.6%) [decrease of 14,964] >> >>Total General/Advanced/Extra - 313,560 (47.6%) [increase of 22,351] >> >>Total all classes - 658,032 (decrease of 16,760) > > > > > > I predicted and warned you all this would happen, but none of you wouldn't > listen. > > Good Hams upset over all the Lids and CB'er like behavior on the bands as > a result of dumbing down license requirements are leaving the hobby. I > can't say I blame them and I hate to see them go. > > On the bright side, there's a lot more ham gear on eBay you can bid on. > > sc Article: 224517 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Fri, 19 May 2006 23:03:49 GMT In article , Owen Duffy wrote: > On Fri, 19 May 2006 21:07:17 GMT, "The always Benevolent dbu." > wrote: > > > >inconsistencies regarding length. From the responses I received here > >there does not seem to be any agreement on length and my question was > >not answered, at least not to my satisfaction. > > That statement reflects your ability to comprehend what was written by > many, rather than what was written. > > If you expected a specific length as implied by your question "What is > the correct way to determine the non-resonant feedline length of a > multiband doublet using 450 ohm open wire." then you have been > dissapointed. > > The consistent answer (even if not always well expressed) was that > length is not particularly critical, though there may be some length / > frequency combinations (that are very dependent on your particular > implementation and equipment) that may challenge your ATU. > > I go along with the advice to use a convenient length of feedline, and > if it is challenging to match up with the ATU, then lengthen the > feedline a little. > > Your dissapointment is perhaps caused by your expectation of a > specific length. > > Owen > -- I keep going back to my very old ARRL antenna handbood which shows a chart of favorable lengths of feedline. Is it wrong? I also would like to point out W8JI website and the lengths of feedline that he recommends, which seems to be consistent with my ARRL handbook, 1960 edition, for this type antenna: http://www.w8ji.com/short_dipoles_and_problems.htm Arrow down. -- Email: dalej2@mac.com Article: 224518 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Fri, 19 May 2006 23:43:02 GMT On Fri, 19 May 2006 23:03:49 GMT, "dale.j. " wrote: >I keep going back to my very old ARRL antenna handbood which shows a >chart of favorable lengths of feedline. Is it wrong? My 2000 ARRL Handbook describes a 135' multiband dipole antenna but does not make any recommendations on preferred feedline lengths. Perhaps they have changed their mind since your edition was published. Given sufficiently good transmission line, lengths to avoid are only lengths to avoid because they present a load that the tuner cannot efficiently transform, or the voltage exceeds the capability of the tuner. Highest voltages usually occur at frequencies much lower than the first parallel resonance... so avoiding resonance doesn't address the most significant region of high voltage. >I also would like to point out W8JI website and the lengths of feedline >that he recommends, which seems to be consistent with my ARRL handbook, >1960 edition, for this type antenna: > >http://www.w8ji.com/short_dipoles_and_problems.htm > He does more than recommend a feedline length in isolation of other parameters. Tom's article is relevant and interesting. You will see that he links to articles by Cebik and myself on the G5RV. Also relevant to the multiband dipole application is the analysis in my article at http://www.vk1od.net/LOLL/index.htm and its reference documents. To get off the 1960 tram, factors that are relevant are: - they probably did not foresee the WARC bands and design to include those bands; - the regions where efficient transformation is a problem are usually very narrow, but quite dependent on the exact implementation (including proximity of other conducting objects, ground / weather conditions), and locating them outside amateur bands may require in-situ tuning. Owen -- Article: 224519 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Fri, 19 May 2006 23:44:37 GMT On Fri, 19 May 2006 21:48:38 GMT, "dale.j. " wrote: >I think you have brought up a good point as to the balance of the >parallel wires which is self canceling. Balanced current may be self cancelling, but currents are not self balancing. Owen -- Article: 224520 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Sat, 20 May 2006 00:45:29 -0000 Message-ID: <126spl9mu0d4079@corp.supernews.com> References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> <1148083790.131137.181880@j33g2000cwa.googlegroups.com> In article <1148083790.131137.181880@j33g2000cwa.googlegroups.com>, wrote: >Maybe, like so many other threads in this group, we are discussing >orthogonal concepts. I believe you're correct. As I see it, in the *general* sense, linearity refers to a relationship between two variables, where the relationship is one of OUT = IN * F + C where F and C are constants (plus a dimensional factor in many cases). In other words, it's a straight-line relationship (hence, the name) between two variables of the same or different dimension. The sort of "linearity" that people usually refer to in electronics, involves voltages and currents (vs. one another). A theoretically perfect resistor, capacitor, or inductor is linear, because (e.g.) the peak current through it has a strictly linear relationship to the peak voltage across it. A semiconductor junction is described as nonlinear, because the current through it is not related to the voltage across it in a strictly linear relationship. The sort of "linearity" which Cecil seems to be referring to (if I understand what he's written correctly) involves a completely different sort of relationship. It's not current-vs-voltage, or voltage-vs-current - it's current-vs-distance. If I recall correctly, an infinitesimally-short "monopole" has a current-vs-distance relationship which is close to linear. A half-wave monopole does not. Nonlinearities of this sort would have entirely different effects on an antenna system than nonlinearities of the voltage-vs-current sort. They're two different beasts entirely. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224521 of rec.radio.amateur.antenna Date: Fri, 19 May 2006 20:28:16 -0500 From: Tom Ring Subject: Re: ARS License Numbers References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> Message-ID: <446e70b0$0$1010$39cecf19@news.twtelecom.net> Slow Code wrote: > > I predicted and warned you all this would happen, but none of you wouldn't > listen. > > Good Hams upset over all the Lids and CB'er like behavior on the bands as > a result of dumbing down license requirements are leaving the hobby. I > can't say I blame them and I hate to see them go. > > On the bright side, there's a lot more ham gear on eBay you can bid on. > > sc And what do these numbers prove? Not a bleeping thing. I don't think any correlation exists between them and current behavior on HF, which I assume, possibly incorrectly, that you are refering to. The biggest idiots on 20m, for instance, are on 14275, both sides are guilty, and I am quite sure that they all got their tickets with CW required. And the problem stations on 75 are quite the same. Which also proves nothing either way. The cleanest, most public oriented operators are on 2m and 70cm, and many, or maybe most, of them did not have to pass any CW exam. They participate in Skywarn, emergency drills, and tons of other things. By and large they are good citizens. The bad actors I have seen come from all parts of the amateur community, with probably the worst from the longest licensed, who seem to feel they have some sort of rights from being around a long time. My personal sample could be wrong, but I don't think so; I've been around a while, too. The older generation always predicts that the current one is going to cause the end of the world. Or whatever imagined disaster they are concerned about. And they are always wrong. tom K0TAR Article: 224522 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> Message-ID: Date: Sat, 20 May 2006 04:50:43 GMT Richard Clark wrote: > In other words, the non-linearity shown by the lack of > congruence to the Cosine curve is not a presumption of non-linearity > by the modeler; it is merely reporting an analysis. You are being fooled by an illusion. Any deviation from single frequency sinusoidal signals would generate harmonics which we know doesn't happen. Your "non-linearity" is not really there. For instance, a decrease in VF may compress the waveform but that is not non-linearity. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224523 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 05:04:21 GMT Tom Donaly wrote: > What he believes is that > since he can't detect any harmonics emanating from a sinusoidally > fed dipole, the current along its length must be a sinusoid. The non-existence of harmonics is prima facie evidence that only single frequency sinusoids exist. A properly functioning antenna system is linear. Any perceived non-linearity is an illusion. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224524 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 05:19:41 GMT Tom Donaly wrote: > Cecil Moore wrote: >> Seems the easiest measurement of nonlinearity would be the >> harmonics (if any) generated by the antenna that do not >> appear in the source signal. > > Which wouldn't tell you a single thing about the current > distribution along the length of the dipole. Yes it would. It would be proof that the current distribution along the length of the dipole is sinusoidal no matter what your illusionary perceptions are telling you. For standing wave antennas, if the source is a pure single frequency sine wave and if no harmonics are generated by the antenna system: 1. The forward wave is sinusoidal. 2. The reflected wave is sinusoidal and coherent with the forward wave. 3. Their superposition results in a sinusoidal standing wave with the same angular velocity. Any non-linearity would introduce harmonics. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224525 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <131n625dmi9j191df9culot6la3btmna6q@4ax.com> <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <7Cobg.29178$4L1.28624@newssvr11.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 05:25:34 GMT Tom Donaly wrote: > People like Cecil, with > home-grown theories, don't ever seem to want things considered in > depth. That's understandable from a psychological standpoint, but > it isn't any help to the rest of us when some of the things the theory > ignores become significant. In the case of antennas, practically > everything is significant. All of the theories I am quoting were developed long before I was born. Almost every technical explanation starts out with simple concepts and proceeds to more complex concepts. For the sake of teaching and understanding simple concepts, the secondary variables are often ignored for the time being. Thus, every textbook on transmission lines starts off with an explanation of lossless lines with perfectly resistive characteristic impedances even though such lines don't exist in reality. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224526 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: ARS License Numbers References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> Message-ID: <1Sxbg.10745$fb2.3968@newssvr27.news.prodigy.net> Date: Sat, 20 May 2006 05:32:45 GMT Slow Code wrote: > I predicted and warned you all this would happen, but none of you wouldn't > listen. If none of us wouldn't listen, doesn't that mean that all of us did listen? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224527 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> Message-ID: Date: Sat, 20 May 2006 05:36:24 GMT Richard Clark wrote: > How much distortion has to exist before you hear it? As this directly > relates to your quoted selection, are we to believe that distortion > does not exist if you cannot perceive it? How about: Distortion can be measured. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224528 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> <1148083790.131137.181880@j33g2000cwa.googlegroups.com> <126spl9mu0d4079@corp.supernews.com> Message-ID: Date: Sat, 20 May 2006 05:47:55 GMT Dave Platt wrote: > The sort of "linearity" which Cecil seems to be referring to (if I > understand what he's written correctly) involves a completely > different sort of relationship. It's not current-vs-voltage, or > voltage-vs-current - it's current-vs-distance. Assuming thin constant diameter wires with a constant Z0 and VF. If the diameter of the wire changes, or Z0 changes, or VF changes, the 'K' term in the cos(KX) expression changes. A change in a constant does NOT produce non-linearity in a linear system. Just because a wave slows down in a medium with a low VF doesn't mean that the system has gone non-linear. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224529 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> Message-ID: Date: Sat, 20 May 2006 05:53:50 GMT Tom Donaly wrote: > Kraus was talking about distribution over _length_. Of course, Kraus is talking about the cos(KX) term where 'X' is _length_ and 'K' is the constant that converts that _length_ into degrees. Given 'K', _length_ and degrees are perfectly correlated. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224530 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 10:50:22 GMT In article , Owen Duffy wrote: > On Fri, 19 May 2006 23:03:49 GMT, "dale.j. " > wrote: > > >I keep going back to my very old ARRL antenna handbood which shows a > >chart of favorable lengths of feedline. Is it wrong? > > My 2000 ARRL Handbook describes a 135' multiband dipole antenna but > does not make any recommendations on preferred feedline lengths. > > Perhaps they have changed their mind since your edition was published. > > Given sufficiently good transmission line, lengths to avoid are only > lengths to avoid because they present a load that the tuner cannot > efficiently transform, or the voltage exceeds the capability of the > tuner. > > Highest voltages usually occur at frequencies much lower than the > first parallel resonance... so avoiding resonance doesn't address the > most significant region of high voltage. > > >I also would like to point out W8JI website and the lengths of feedline > >that he recommends, which seems to be consistent with my ARRL handbook, > >1960 edition, for this type antenna: > > > >http://www.w8ji.com/short_dipoles_and_problems.htm > > > > He does more than recommend a feedline length in isolation of other > parameters. > > Tom's article is relevant and interesting. > > You will see that he links to articles by Cebik and myself on the > G5RV. > > Also relevant to the multiband dipole application is the analysis in > my article at http://www.vk1od.net/LOLL/index.htm and its reference > documents. > > To get off the 1960 tram, factors that are relevant are: > - they probably did not foresee the WARC bands and design to include > those bands; > - the regions where efficient transformation is a problem are usually > very narrow, but quite dependent on the exact implementation > (including proximity of other conducting objects, ground / weather > conditions), and locating them outside amateur bands may require > in-situ tuning. > > Owen > -- Thanks for all the links which I am reading. My dipole is about 126 feet long which should be about right for 3.7 Mhz. I mostly use it on 75 M. The new feedline I have installed is a bit shorter than what I was using, I think it's now around 47 feet, the old stuff was 50 plus feet. I notice my Johnson matchbox now finds it somewhat difficult to tune up this antenna on 40 M so I may have to add on a few feet. A couple of years ago I had two loading coils on each leg of the tuner output and the whole thing was a perfect match on 75 and 40, all I had to do was change the bandswitch on the matchbox, nothing else. I guess I'll just not worry about length of feedline only to make it tune nicely and fit the physical space from the antenna. 73 dale -- Email: dalej2@mac.com Article: 224531 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 12:17:53 GMT dale.j. wrote: > Thanks for all the links which I am reading. My dipole is about 126 > feet long which should be about right for 3.7 Mhz. I mostly use it on > 75 M. The new feedline I have installed is a bit shorter than what I > was using, I think it's now around 47 feet, the old stuff was 50 plus > feet. I notice my Johnson matchbox now finds it somewhat difficult to > tune up this antenna on 40 M so I may have to add on a few feet. Did you take a look at the information on my web page at: http://www.qsl.net/w5dxp/notuner.htm It tells you everything you need to know about that antenna including why 47 feet is not the best feedline length on 40m. In particular, the chart at: http://www.qsl.net/w5dxp/pnts130.gif shows the best lengths for 40m to be 30 feet or 92 feet. A good compromise single length for all-HF-band operation is 100 feet. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224532 of rec.radio.amateur.antenna From: Ron Subject: Re: ARS License Numbers Date: 20 May 2006 10:24:01 EDT Message-ID: <446F27FE.4000903@yahoo.com> References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> >> On the bright side, there's a lot more ham gear on eBay you can bid on. > > > But...what good does having a bunch of gear if there is nobody to talk > to or listen to? I guess it's good if you're starting a radio museum... Actually there is less of the good stuff on eBay than there was 2 years ago. Plus prices for the rare stuff still keeps going up. Article: 224533 of rec.radio.amateur.antenna From: Ron Subject: Re: ARS License Numbers Date: 20 May 2006 10:27:46 EDT Message-ID: References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> >>I don't think any correlation exists between them and current behavior >>on HF, which I assume, possibly incorrectly, that you are refering to. > >>The biggest idiots on 20m, for instance, are on 14275, both sides are >>guilty, and I am quite sure that they all got their tickets with CW >>required. And the problem stations on 75 are quite the same. Which >>also proves nothing either way. > > > it does prove that CW testing is at best poor proof of screening out > bad ops Yup if you check it out most of the crap on HF is from old farts that passed their tests with the CW requirement. From JT Mon May 22 21:17:25 EDT 2006 Article: 224534 of rec.radio.amateur.antenna From: JT (jt@trek.net) Newsgroups: rec.radio.amateur.antenna Subject: Re: question about tunable capacitor: how to mount ?? X-Newsreader: NewsLeecher v3.0 Final (http://www.newsleecher.com) References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Lines: 13 Message-ID: X-Complaints-To: abuse@usenetserver.com X-Abuse-Info: Please be sure to forward a copy of ALL headers X-Abuse-Info: Otherwise we will be unable to process your complaint properly. NNTP-Posting-Date: Sat, 20 May 2006 11:31:52 EDT Date: Sat, 20 May 2006 15:31:52 GMT Path: news.unc.edu!canoe.uoregon.edu!newshub.sdsu.edu!nx01.iad01.newshosting.com!newshosting.com!208.49.83.154.MISMATCH!atl-c08.usenetserver.com!news.usenetserver.com!pc03.usenetserver.com!fe42.usenetserver.com.POSTED!334b1f4d!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:224534 Are you going to run QRP? I made mind out of 1/2 copper tubing and made loop from coax at the top the tuning capacitor I used was from ebay the spacing between the tuner is 1/4 inch my tuner is 4" wide 6"long and about 3 1/2 high first contact 22" off ground was Detroit Michigan I'm in Dunedin Florida second contact was Canada for about a half hour. with a small tunable cap you will have arking I am running 100 watts. Jim De W8OLD -- ---------------------------------------------- Posted with NewsLeecher v3.0 Final * Binary Usenet Leeching Made Easy * http://www.newsleecher.com/?usenet ---------------------------------------------- From JT Mon May 22 21:17:26 EDT 2006 Article: 224535 of rec.radio.amateur.antenna From: JT (jt@trek.net) Newsgroups: rec.radio.amateur.antenna Subject: Re: question about tunable capacitor: how to mount ?? X-Newsreader: NewsLeecher v3.0 Final (http://www.newsleecher.com) References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Lines: 8 Message-ID: X-Complaints-To: abuse@usenetserver.com X-Abuse-Info: Please be sure to forward a copy of ALL headers X-Abuse-Info: Otherwise we will be unable to process your complaint properly. NNTP-Posting-Date: Sat, 20 May 2006 11:37:57 EDT Date: Sat, 20 May 2006 15:37:57 GMT Path: news.unc.edu!canoe.uoregon.edu!newshub.sdsu.edu!nx01.iad01.newshosting.com!newshosting.com!208.49.83.154.MISMATCH!atl-c08.usenetserver.com!news.usenetserver.com!pc03.usenetserver.com!fe42.usenetserver.com.POSTED!334b1f4d!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:224535 Try this site www.kr1st.com.magloop.htm this one I built and am running 100 watts. 73's de Jim W8OLD -- ---------------------------------------------- Posted with NewsLeecher v3.0 Final * Binary Usenet Leeching Made Easy * http://www.newsleecher.com/?usenet ---------------------------------------------- Article: 224536 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> Message-ID: Date: Sat, 20 May 2006 15:51:45 GMT Tom Donaly wrote: > The purpose of most antennas is to radiate electromagnetic waves. > That means there is loss. It also means that the current envelope is > affected. That's one of the reasons we use EZNEC. The current envelope is affected but remains a linear system function since it is the result of superposition which itself is a linear system function. > I suppose, Cecil, > that if you keep repeating the same old tired line, over and over > again, you might find someone who will agree with you. Certainly, > no antenna measurement would. The current envelope is a linear system function. I am repeating the rules and laws of mathematics. Sounds like you need to review the definition of linear systems. You can do that at: http://www.cns.nyu.edu/~david/linear-systems/linear-systems.html In particular, quoting: "Systems that satisfy both homogeneity and additivity are considered to be linear systems. These two rules, taken together, are often referred to as the principle of superposition." In general, antennas are linear systems that satisfy the principle of superposition. If they were non-linear, they would not satisfy the principle of superposition. Two linear system functions, like forward waves and reflected waves, cannot superpose to a non-linear function. Therefore, standing waves are linear, not non-linear, functions. To argue otherwise exhibits a certain degree of ignorance. Until the obvious mathematical misconception is corrected, no rational discussion is possible. To the best of my knowledge, Maxwell's equations are also linear system functions so claims of non-linearity also contradict Maxwell's equations. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224537 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 16:47:55 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Thanks for all the links which I am reading. My dipole is about 126 > > feet long which should be about right for 3.7 Mhz. I mostly use it on > > 75 M. The new feedline I have installed is a bit shorter than what I > > was using, I think it's now around 47 feet, the old stuff was 50 plus > > feet. I notice my Johnson matchbox now finds it somewhat difficult to > > tune up this antenna on 40 M so I may have to add on a few feet. > > Did you take a look at the information on my web page at: > > http://www.qsl.net/w5dxp/notuner.htm > > It tells you everything you need to know about that antenna > including why 47 feet is not the best feedline length on 40m. > In particular, the chart at: > > http://www.qsl.net/w5dxp/pnts130.gif > > shows the best lengths for 40m to be 30 feet or 92 feet. > A good compromise single length for all-HF-band operation > is 100 feet. Yes I did Cecil. I went out and remeasured and found that I have about 67 total feet of feed line now. I may shorten that up again. I'll re-check the links you provided, thanks. -- Email: dalej2@mac.com Article: 224538 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 16:55:12 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Thanks for all the links which I am reading. My dipole is about 126 > > feet long which should be about right for 3.7 Mhz. I mostly use it on > > 75 M. The new feedline I have installed is a bit shorter than what I > > was using, I think it's now around 47 feet, the old stuff was 50 plus > > feet. I notice my Johnson matchbox now finds it somewhat difficult to > > tune up this antenna on 40 M so I may have to add on a few feet. > > Did you take a look at the information on my web page at: > > http://www.qsl.net/w5dxp/notuner.htm > > It tells you everything you need to know about that antenna > including why 47 feet is not the best feedline length on 40m. > In particular, the chart at: > > http://www.qsl.net/w5dxp/pnts130.gif > > shows the best lengths for 40m to be 30 feet or 92 feet. > A good compromise single length for all-HF-band operation > is 100 feet. BTW Cecil, I could never get 100 feet of open wire in my back yard unless I coil it up or string it all over the place and that would not be good. Isn't there a shorter length that would work for 75 & 40? 73 Dale j. -- Email: dalej2@mac.com Article: 224539 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> <076dnUhaopMRoPLZRVny0Q@bt.com> Message-ID: Date: Sat, 20 May 2006 17:39:44 GMT Reg Edwards wrote: >>I suppose, Cecil, >>that if you keep repeating the same old tired line, over and over >>again, you might find someone who will agree with you. > > ========================================= > > I agreed with Cecil the first time he said it. > But I'm only a foreigner. > So whatever I say doesn't carry any weight. > Or does it? > ---- > Reg. > > You're the master of simple approximation, Reg. Cecil thinks your simplified ideas are received wisdom. Knowing you, I find it hard to believe you'd ever agree with anyone. 73, Tom Donaly, KA6RUH Article: 224540 of rec.radio.amateur.antenna From: "John, N9JG" References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Subject: Re: question about tunable capacitor: how to mount ?? Date: Sat, 20 May 2006 15:39:48 -0400 Message-ID: <4Yednd2BbdIf7fLZRVn-uQ@insightbb.com> That link doesn't "JT" wrote in message news:pJGbg.65799$w85.1909@fe42.usenetserver.com... > Try this site www.kr1st.com.magloop.htm > this one I built and am running 100 watts. 73's de Jim W8OLD > -- > ---------------------------------------------- > Posted with NewsLeecher v3.0 Final > * Binary Usenet Leeching Made Easy > * http://www.newsleecher.com/?usenet > ---------------------------------------------- > Article: 224541 of rec.radio.amateur.antenna From: "Dave" References: <3nobg.29166$4L1.25712@newssvr11.news.prodigy.com> <23819-446E3241-1372@storefull-3252.bay.webtv.net> <1148083790.131137.181880@j33g2000cwa.googlegroups.com> Subject: Re: FIGHT! FIGHT! FIGHT! Date: Sat, 20 May 2006 19:40:04 -0000 Message-ID: "Richard Clark" wrote in message news:s4lu62drhct2cuncrf9ti6kf1r27mle51o@4ax.com... > On Sat, 20 May 2006 12:14:29 -0000, "Dave" wrote: > >>KEEP IT GOING! > > Dave, your trolling effort is rather a poor substitute for the sense > of accomplishment. Too many do it far better, with more flair, and > offer more entertainment than this pallid use of the CAPS KEYS. I'm just cheering you on... besides if I'm going to troll I might as well abandon some other parts of decency in the process. And it doesn't seem like anyone cares, even with the obvious thread title it took off all on its own. Article: 224542 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 19:52:32 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > > Cecil Moore wrote: > >>http://www.qsl.net/w5dxp/pnts130.gif > >> > >>shows the best lengths for 40m to be 30 feet or 92 feet. > > > > Yes I did Cecil. I went out and remeasured and found that I have about > > 67 total feet of feed line now. > > (30+92)/2 = 61 feet, worst case for feeding that dipole > on 40m. For all-HF-band operation, I would highly > recommend a feedline length of 100 feet. You can use > a 60 foot run of small non-conductive rope with the > ladder-line spiraled around it and tie-wrapped to it > to obtain the better case 100 feet. Well I'll give it some thought. All I need is to find room somehow for 33 more feet of ladder. Maybe I will try it jury rigged first to see how it tunes, but not today, it rains. Doesn't the matchbox do the electrical tuning of the feedline instead of using fixed lengths as you are doing? As you said the length I have now does not tune very well on 40, I can get it to work but it's like opening a safe. I just dug out my Drake MN-2700 user manual and it says to use 135 foot long horizontal fed in the middle with 67 feet of ladder. Weird, this stuff is worse than making a pizza. Dale j. -- Email: dalej2@mac.com From Mon May 22 21:17:26 EDT 2006 Article: 224543 of rec.radio.amateur.antenna NNTP-Posting-Date: Sat, 20 May 2006 16:00:18 -0500 From: Dan Richardson <> Newsgroups: rec.radio.amateur.antenna Subject: Re: Multiband doublet feedline length Date: Sat, 20 May 2006 14:00:04 -0700 Message-ID: <7q0v62ptc4cdu3h3ce41kemo09ef8vmcc9@4ax.com> References: <2jlu62hksmq85k3fumin30cu0r627o319i@4ax.com> X-Newsreader: Forte Agent 1.93/32.576 English (American) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 20 NNTP-Posting-Host: 68.64.59.124 X-Trace: sv3-tfeNlIgfKfxFWy0UCtjTRx0wuLq9kbm0Qi1bly0959G6kT2RL3rMRRShY1nX52JlzUgrPUFhOHaB4ut!xb5S9gYROltG1NDNZ9hjFguE/AJkYsxzNWNIYaQ9hEikTsxgZinbkotEQK0PANr3xccLRWSBiwyq!o0uHHZIwRSSlG2ZRvktB X-Complaints-To: abuse@adelphia.net X-DMCA-Complaints-To: copyright@adelphia.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Path: news.unc.edu!elk.ncren.net!newsflash.concordia.ca!News.Dal.Ca!ursa-nb00s0.nbnet.nb.ca!nf3.bellglobal.com!border2.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.adelphia.com!news.adelphia.com.POSTED!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:224543 On Sat, 20 May 2006 17:57:10 GMT, Cecil Moore wrote: >Richard Clark wrote: >> There is one way to obtain a simple answer, you make the transmission >> line an odd 8th wave long which will offer reasonable tuning. This >> insight comes courtesy of Walt Maxwell's techniques offered for >> measuring steep loads found in his classic "Reflections." > >Where does Walt say that? In chapter 15. In my many years I have come to a conclusion that one useless man is a shame, two is a law firm, and three or more is a congress. - John Adams email: k6mhearrlnet http://www.k6mhe.com/ Article: 224544 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Sat, 20 May 2006 16:33:48 -0500 Message-ID: <4754-446F8B3C-20@storefull-3255.bay.webtv.net> References: <076dnUhaopMRoPLZRVny0Q@bt.com> Reg, G4FGQ wrote: "I agreed with Cecil the first time he said it. But I`m only a foreigner. So whatever I say doesn`t carry any weight. Or does it?" We all are foreigners in most places. Reg`s reputation precedes him so he always carries a lot of weight. Best regards, Richard Harrison, KB5WZI Article: 224545 of rec.radio.amateur.antenna From: ehramm@dk3uz.ampr.org (Edmund H. Ramm) Subject: Re: question about tunable capacitor: how to mount ?? References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Message-ID: Date: Sat, 20 May 2006 21:49:19 GMT In JT (jt@trek.net) writes: > [...] > I made mind out of 1/2 copper tubing > [...] You aren't possibly aka "Frankenstein"? SCNR & 73, Eddi ._._. -- e-mail: dk3uz AT darc DOT de | AMPRNET: dk3uz@db0hht.ampr.org If replying to a Usenet article, please use above e-mail address. Linux/m68k, the best U**x ever to hit an Atari! Article: 224546 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> Subject: Re: ARS License Numbers Message-ID: Date: Sat, 20 May 2006 15:15:39 -0700 > > I am quite sure that they all got their tickets with CW > > required. And the problem stations on 75 are quite the same. Which > > also proves nothing either way. > > it does prove that CW testing is at best poor proof of screening out > bad ops There's no test for one important ham skill: typing. I didn't appreciate how important it is until I learned that one of my pro-Morse buddies does all of his sending with a computer. (He can send with a key but doesn't know where his is.) He says he copies with the computer, too, although he can follow along with the audio. I asked around and found this practice is far from rare; I'm not sure "common" is the right word, though. We also might want to test for basic language skills, including punctuation. While it's not always true, the disagreeable transmissions (and NG posts) often make the speakers/writers sound pretty ignorant. Article: 224547 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: <2jlu62hksmq85k3fumin30cu0r627o319i@4ax.com> Date: Sat, 20 May 2006 22:20:04 GMT On Sat, 20 May 2006 10:53:04 -0700, Richard Clark wrote: >On Fri, 19 May 2006 21:50:35 GMT, Owen Duffy wrote: > >>Your dissapointment is perhaps caused by your expectation of a >>specific length. > >Hi Owen, > >There is one way to obtain a simple answer, you make the transmission >line an odd 8th wave long which will offer reasonable tuning. This >insight comes courtesy of Walt Maxwell's techniques offered for >measuring steep loads found in his classic "Reflections." > Richard, The original question was regarding a multiband double of unspecified length. Aren't there lengths of the dipole that in concert with an eight wave feedline would challenge the ATU? Have you made assumptions about the doublet length in making this recommendation? Owen -- Article: 224548 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <1k1o621hg5n9l78mcqu9smlahgvbtn6fgh@4ax.com> <1147966925.828695.186160@u72g2000cwu.googlegroups.com> <3mcp62pih4dris998tg62cs877v9vfdf3u@4ax.com> <446d0af6$0$6147$39cecf19@news.twtelecom.net> <29lq62lil71ijqbtfesdhiks2imt6p80i2@4ax.com> <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> <076dnUhaopMRoPLZRVny0Q@bt.com> Message-ID: Date: Sat, 20 May 2006 22:19:31 GMT Tom Donaly wrote: > You can still pretend a dipole is a "linear system," as you > call it, and still understand that the current envelope is not > a simple sine function. Diverting to a "simple" sine function in the same spirit as diverting to a "small" loading coil? If you were always talking about a perfect sine wave, you should have said so long before now and nobody would have disagreed with you. > The Achilles heel of all your reflection > mechanics ideas is the assumption that everything is lossless. That's NOT the assumption. The assumption is that lossless systems are easiest to understand so let's understand them first before we move on to something more complex. You guys have proven that you don't even understand the simple lossless condition. > (Not to mention the fact that it's supposed to exist in outer > space.) You and Reg like to think of a dipole as a transmission line, > and Reg can even tell you its characteristic impedance (average). What > neither he nor you ever mention is the alpha part of the > propagation constant. That's the important part, though, since it > signifies radiation, the very thing the antenna was designed to do. Only about 1 dB of the steady-state energy stored in a 1/2WL dipole is radiated so radiation is not the largest effect. The radiation from an antenna can be simulated by using resistance wire to simulate a 1 dB loss in a transmission line. The reason that I have rarely mentioned such is that you guys don't understand enough of the basics to proceed to those more complex examples. > By the way, why are you quoting from a network theory book when not > too long ago you were ranting and raving about the invalidity of the > lumped constant model? The lumped constant model is valid under certain conditions. What I object to is its use under known invalid conditions. The lumped constant model and distributed network model are both *linear systems*. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224549 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 22:25:50 GMT dale.j. wrote: > Doesn't the matchbox do the > electrical tuning of the feedline instead of using fixed lengths as you > are doing? If it's a Johnson Matchbox, it has a limited tuning range. But for dipoles 1/2WL at the lowest frequency of operation, feeding in the rough vicinity of the current maximum point will work. For 80m and 40m, you might get by with 80 feet of feedline. > I just dug out my Drake MN-2700 user manual and it says to use 135 foot > long horizontal fed in the middle with 67 feet of ladder. Weird, this > stuff is worse than making a pizza. If that is for 80m or 40m, the Drake must like very high impedances. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224550 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Multiband doublet feedline length Date: Sat, 20 May 2006 17:32:39 -0500 Message-ID: <23820-446F9907-347@storefull-3252.bay.webtv.net> References: Dale j wrote: "I just dug out my Drake MN-2700 user manual and it says to use 135 fiit long horizontal fed in the middle with 67 feet of ladder." Drakes idea is probably a versatile antenna similar to the one on page 22.11 of the 2006 ARRL Handbook. At 80 meters it is about 1/2-wavelength fed with about 1/4-wavelength of feedline. A grounded radio presents a high impedance to comon-mode travel where the line meets the antenna at the resonant frequency of the antenna. Your radio should not bite you on 80 meters and a versatile tuner should make the antenna useable through 10 meters. The pattern goes through a lot of change in that range of frequencies. This is predicted by a modeling program and some of the transition is shown in the handbook. Best regards, Richard Harrison, KB5WZI Article: 224551 of rec.radio.amateur.antenna From: "Sal M. Onella" References: Subject: Re: Replacing car broadcast antenna for AM/FM/2M/70cm Message-ID: <_eNbg.27116$QP4.16428@fed1read12> Date: Sat, 20 May 2006 16:03:22 -0700 "yea right" wrote in message news:pan.2006.05.20.05.29.17.886633@spam.spam... > I am looking for a commercial antenna that I can replace the regular > broadcast antenna on my car with, that would still service the car > broadcast radio but have bandpass/bandblock filters so that I can also use > the same antenna for my mobile 2m/70cm FM radio. > > Is there such a beast? First, I couldn't find you an HF/VHF diplexer, but you can build one. http://home.datacomm.ch/hb9abx/diplhf6m-vuhf.html Second, do you have to have both radios functional simultaneously or are you willing to switch one antenna between to radios? If you're hamming you probably don't want the BCST radio playing in the background. Here's my story: Years ago, I developed an open shield in my van's BCST antenna and I didn't want to tear apart the dashboard to replace the antenna, so I put a Motorola-to-BNC adapter into the back of the car radio. From there I dropped a short length of coax down, ran it under the floormat to a point behind the seat and connected it to my MFJ magmount's coax. (If I'm hamming, I disconnect the BCST radio and use the magmount as MFJ intended. I never bothered to install a switch.) My $15.95 (last time I bought one) MFJ Dual Band magmount works perfectly as a substitute for the car's BCST antenna -- AM & FM just fine. BONUS: On long inter-city trips, I swap out the stock whip for a longer, straight whip and the BCST reception is just wonderful. Article: 224552 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sat, 20 May 2006 23:40:11 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Doesn't the matchbox do the > > electrical tuning of the feedline instead of using fixed lengths as you > > are doing? > > If it's a Johnson Matchbox, it has a limited tuning range. > But for dipoles 1/2WL at the lowest frequency of operation, > feeding in the rough vicinity of the current maximum point > will work. For 80m and 40m, you might get by with 80 feet > of feedline. > > > I just dug out my Drake MN-2700 user manual and it says to use 135 foot > > long horizontal fed in the middle with 67 feet of ladder. Weird, this > > stuff is worse than making a pizza. > > If that is for 80m or 40m, the Drake must like very high > impedances. I'll give the 100 ft a go and let you know. When you say wind the ladder line around a tag rope, I assume you mean to use ties around one wire of the ladder and make the loop maybe a foot in diameter or maybe 6 inches? Sort of a helix affair. Would that cause a problem with the ladder being so close to the turns? I've read where I should keep the ladder from sharp angles and away from metal objects so as not to unbalance the line and destroy the cancel properties of ladder line. The more I read about this the more it looks like black magic. Dalej. -- Email: dalej2@mac.com Article: 224553 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> <1148164087.750699.162430@i39g2000cwa.googlegroups.com> Subject: Re: ARS License Numbers Message-ID: Date: Sat, 20 May 2006 17:00:22 -0700 "an_old_friend" wrote in message news:1148164087.750699.162430@i39g2000cwa.googlegroups.com... > > We also might want to test for basic language skills, including punctuation. > why? > > why do do we want to restrict the numer of hams in that manner That's a persuasive argument and you've definitely brought some clarity to the issue. Thanks so much. Article: 224554 of rec.radio.amateur.antenna From: "CW" References: Subject: Re: Multiband doublet feedline length Message-ID: Date: Sun, 21 May 2006 00:05:35 GMT Look at his site. Cecil does not use a tuner. "dale.j. " wrote in message news:nos.pamz-7FA88A.14520920052006@news-rdr-03.rdc-kc.rr.com... >Doesn't the matchbox do the > electrical tuning of the feedline instead of using fixed lengths as you > are doing? Article: 224555 of rec.radio.amateur.antenna From: "The always Benevolent dbu." Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 00:14:50 GMT In article , "CW" wrote: > Look at his site. Cecil does not use a tuner. > > "dale.j. " wrote in message > news:nos.pamz-7FA88A.14520920052006@news-rdr-03.rdc-kc.rr.com... > >Doesn't the matchbox do the > > electrical tuning of the feedline instead of using fixed lengths as you > > are doing? Yes I have, but I think we are talking about more than one dimension. Dalej. -- Article: 224556 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1148034389.195497.233470@i40g2000cwc.googlegroups.com> <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <1148058870.661052.17230@j73g2000cwa.googlegroups.com> <0xnbg.78624$H71.77915@newssvr13.news.prodigy.com> <4QFbg.90097$dW3.25856@newssvr21.news.prodigy.com> <076dnUhaopMRoPLZRVny0Q@bt.com> Message-ID: Date: Sun, 21 May 2006 00:48:42 GMT Richard Clark wrote: > On Sat, 20 May 2006 17:39:44 GMT, "Tom Donaly" > wrote: > > >>Cecil thinks your simplified ideas are received wisdom. > > > Hi Tom, > > Is there some suggestion of smoldering bush in this parable? > Commandments that are unzipped and ready for immediate entablature? > > 73's > Richard Clark, KB7QHC Hi Richard, Yes, but there's some evidence Cecil is about to apostatize. I hope he doesn't end up wandering in the wilderness. 73, Tom Donaly, KA6RUH Article: 224557 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Sun, 21 May 2006 01:12:16 GMT On Sat, 20 May 2006 16:47:55 GMT, "dale.j. " wrote: >In article , > Cecil Moore wrote: > >> dale.j. wrote: >> > Thanks for all the links which I am reading. My dipole is about 126 >> > feet long which should be about right for 3.7 Mhz. I mostly use it on >> > 75 M. The new feedline I have installed is a bit shorter than what I >> > was using, I think it's now around 47 feet, the old stuff was 50 plus >> > feet. I notice my Johnson matchbox now finds it somewhat difficult to >> > tune up this antenna on 40 M so I may have to add on a few feet. >> >> Did you take a look at the information on my web page at: >> >> http://www.qsl.net/w5dxp/notuner.htm >> >> It tells you everything you need to know about that antenna >> including why 47 feet is not the best feedline length on 40m. >> In particular, the chart at: >> >> http://www.qsl.net/w5dxp/pnts130.gif >> >> shows the best lengths for 40m to be 30 feet or 92 feet. >> A good compromise single length for all-HF-band operation >> is 100 feet. > >Yes I did Cecil. I went out and remeasured and found that I have about >67 total feet of feed line now. I may shorten that up again. I'll >re-check the links you provided, thanks. 47', now 67'... slowly more information emerges, even if changing. The following is a one band (40m) perspective of your multiband antenna. If you have a 126' dipole (as you said), it has a feedpoint impedance that is quite high around 7MHz because it is close to a full wave dipole which has a feedpoint impedance around 4200+j0 (depending on height, ground etc). A 126' dipole 15m above average ground is probably around 3600+j1400 at 7.2MHz. If you were using 67' of Wireman 551, you would expect the load seen by the tuner to be around 660-j1400 ohms (assuming an effective 1:1 balun)... which is not extreme, but it is fairly high and might challenge some ATUs. Lengthening the feedline will bring the load impedance down fairly quickly, just another 10' (ie 77' overall) gives 90-j400. Shortening the feedline a little from 67' will make it worse, 62.5' will give you the maximum load impedance of 3500+ ohms. Standing back and taking a system view, it is questionable whether making the dipole resonant or very close to resonance at 3.7MHz as you have done, makes harmonic operation easier. It certainly presents the worst case feedline VSWR on 7MHz, the highest feedline voltage (>2500V peak at 1kW), though the transmission line loss for 90' of 551 is only 0.6dB in the above scenario. Owen PS: I know conventional wisdom is to make a multiband dipole half wavelength at the lowest operating frequency, and the ARRL shows such an antenna with 130' dipole length. It turns out that if a dipole with practical length of open wire feeder to an ATU at the tx is less than about 35% of a wavelength, system losses increase dramatically with reduced length, so the dipole should not be less than about 35% of wavelength at the lowest frequency. You can see the effect in Fig 2 of my article at http://www.vk1od.net/LOLL/index.htm . In that case, the system losses with a 66' dipole are acceptable down to about 5.5MHz, for 3.5MHz the dipole needs to be greater than 5.5/3.5*66' or 103'. -- Article: 224558 of rec.radio.amateur.antenna Message-ID: <446FD707.D3B5E8CD@shaw.ca> From: Irv Finkleman Subject: Re: question about tunable capacitor: how to mount ?? References: <47391$44497c86$45011502$16426@KNOLOGY.NET> Date: Sun, 21 May 2006 02:56:52 GMT "jt@trek.net" wrote: > > Try this site www.kr1st.com.magloop.htm > this one I built and am running 100 watts. 73's de Jim W8OLD > -- > ---------------------------------------------- > Posted with NewsLeecher v3.0 Final > * Binary Usenet Leeching Made Easy > * http://www.newsleecher.com/?usenet > ---------------------------------------------- The link should read http://www.kr1st.com/magloop.htm Irv VE6BP -- -------------------------------------- Diagnosed Type II Diabetes March 5 2001 Beating it with diet and exercise! 297/215/210 (to be revised lower) 58"/43"(!)/44" (already lower too!) -------------------------------------- Visit my HomePage at http://members.shaw.ca/finkirv/index.html Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada Article: 224559 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Sat, 20 May 2006 22:46:42 -0500 Message-ID: <21360-446FE2A2-1481@storefull-3257.bay.webtv.net> References: Mike, W4EF wrote: "I would agree, Richard, but at HF frequencies, the current path around the shield isn`t real;ly broken by the gap." To best describe what broken means, a picture helps. There is a picture on page 13.18 of the 2006 ARRL Handbook. Fig 13.26 has a legend which says: "To prevent shielding of the loop from magnetic fields, leave the shield unconnected at one end." I think the handbook has it right. Best regards, Richard Harrison, KB5WZI Article: 224560 of rec.radio.amateur.antenna Subject: Auto-Tuners with balanced antenna? From: Ed Message-ID: Date: 21 May 2006 04:12:31 GMT Any recommendations for an automatic tuner that will work well with balanced antennas fed with 600 ohm ladder line? Specifically, I have in mind a 160M dipole fed with ladder line. Ed K7AAT Article: 224561 of rec.radio.amateur.antenna From: m II Subject: Re: HF broadcasting antennas References: <5s84k3-2id.ln1@remote.clifto.com> Message-ID: Date: Sun, 21 May 2006 04:25:44 GMT clifto wrote: > sipa wrote: > >>First please excuse me for my bad english. > > > 1. Your English is far better than my Hungarian. Mindenkinek a Magyarja job mint az Angolod.. mihaly (Doing the Dance of Joy..) II Article: 224562 of rec.radio.amateur.antenna From: m II Subject: Re: HF broadcasting antennas References: <5s84k3-2id.ln1@remote.clifto.com> Message-ID: Date: Sun, 21 May 2006 04:27:54 GMT m II wrote: > clifto wrote: > > >>sipa wrote: >> >> >>>First please excuse me for my bad english. >> >> >>1. Your English is far better than my Hungarian. The poster's .sig was a Slavic language, not Hungarian. mike Article: 224563 of rec.radio.amateur.antenna Subject: Re: Auto-Tuners with balanced antenna? From: Dave Oldridge References: Message-ID: Date: Sun, 21 May 2006 06:53:58 GMT Ed wrote in news:Xns97C9D7E3CBC77spectrumhogstarbandn@198.186.192.196: > > Any recommendations for an automatic tuner that will work well with > balanced antennas fed with 600 ohm ladder line? > > Specifically, I have in mind a 160M dipole fed with ladder line. Well, I've not tried THAT, specifically, but my MFJ939B will load a 50foot piece of what looks like 200 or 150 ohm twinlead with half of one side stripped away just fine, if I connect up the internal balun. And I mean LOAD it--on any frequency from 1.8 to 30mhz. I've also loaded small loops with it well off their resonant points and use it all the time to lead hamstick whips well off their resonant points. I don't think you'd have any real trouble as long as the 600 ohm line ran straight away from the antenna, at least in the near field. -- Dave Oldridge+ ICQ 1800667 Article: 224564 of rec.radio.amateur.antenna From: KC1DI Subject: Re: Auto-Tuners with balanced antenna? Date: Sun, 21 May 2006 08:41:18 -0400 Message-ID: References: Ed wrote: > Any recommendations for an automatic tuner that will work well with > balanced antennas fed with 600 ohm ladder line? > > Specifically, I have in mind a 160M dipole fed with ladder line. > > > Ed K7AAT I use the LDG z100 with and external Balun Works well for me. 73 Dave kc1di Article: 224565 of rec.radio.amateur.antenna From: "Lew" References: Subject: Re: Auto-Tuners with balanced antenna? Message-ID: Date: Sun, 21 May 2006 09:01:24 -0400 I run a SGC ATU to my Dipole with ladder line with no problems Lew "KC1DI" wrote in message news:e4pn0l$f4h$1@emma.aioe.org... > Ed wrote: >> Any recommendations for an automatic tuner that will work well with >> balanced antennas fed with 600 ohm ladder line? >> >> Specifically, I have in mind a 160M dipole fed with ladder line. >> >> >> Ed K7AAT > > > I use the LDG z100 with and external Balun Works well for me. > 73 Dave kc1di Article: 224566 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Multiband doublet feedline length Message-ID: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> References: Date: Sun, 21 May 2006 13:22:18 GMT On Tue, 16 May 2006 22:55:13 GMT, "dale.j. " wrote: >What is the correct way to determine the non-resonant feedline length of >a multiband doublet using 450 ohm open wire. > > tnx >Dale I have a 130 foot dipole, about 25' high in the middle, 20' at the ends, fed with 47' of the Wireman's ladderline, going directly to the 4-1 balun of an old mfj989c tuner. From everything I've read in this thread, it shouldn't tune worth a darn on 40 meters, but I can get a 1-1 swr match on 40, as well as every other band. I guess all you can do is put it up and see if it works :-) One of these days I might try Cecil's idea, a 100 foot feed of ladderline, but I'd have to string about 50' of that back and forth to make it work. bob k5qwg Article: 224567 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 13:43:59 GMT dale.j. wrote: > I'll give the 100 ft a go and let you know. > > When you say wind the ladder line around a tag rope, I assume you mean > to use ties around one wire of the ladder and make the loop maybe a foot > in diameter or maybe 6 inches? Sort of a helix affair. Would that > cause a problem with the ladder being so close to the turns? You are forming 100 ft. of ladder-line into a 50 ft. long helix. The spacing on the turns will not be a problem as it will be a very loosely wound helix. Tie a knot in the messenger string every 10 inches. Anchor one point of the ladder-line to a knot in the messenger string using black tie-wraps. Take 20 inches of ladder-line and anchor it at the next knot down from the first knot. That will give you one turn of the helix. Repeat until you have a 100 foot feedline. If you didn't want to use tie-wraps, you could tie the 10 inch spaced knots through the ladder-line every 20 inches of ladder-line. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224568 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 13:49:14 GMT CW wrote: > Look at his site. Cecil does not use a tuner. > > "dale.j. " wrote: >>Doesn't the matchbox do the electrical tuning of the >> feedline instead of using fixed lengths as you >>are doing? When I was using an ICOM-706, I didn't use a tuner. Now that I have an ICOM-756PRO, I choose a feedline length that resonates the antenna system in the center of a band and then use the autotuner for excursions toward band edges. Making the feedline a fixed length of 100 ft. and then using a tuner is somewhat similar to what I am doing now. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224569 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 13:55:24 GMT Owen Duffy wrote: > It turns out that if a dipole with practical length of open wire > feeder to an ATU at the tx is less than about 35% of a wavelength, > system losses increase dramatically with reduced length, so the dipole > should not be less than about 35% of wavelength at the lowest > frequency. Agrees pretty closely with Walter Maxwell's 3/8 wavelength minimum dipole advice. > You can see the effect in Fig 2 of my article at > http://www.vk1od.net/LOLL/index.htm . In that case, the system losses > with a 66' dipole are acceptable down to about 5.5MHz, for 3.5MHz the > dipole needs to be greater than 5.5/3.5*66' or 103'. Agrees pretty closely with the length of a G5RV. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224570 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT? Here is another W8JI myth bone! References: <21360-446FE2A2-1481@storefull-3257.bay.webtv.net> <9f6dndFM6YCPt-3ZRVn-rQ@comcast.com> <1148204558.861148.41500@j55g2000cwa.googlegroups.com> Message-ID: Date: Sun, 21 May 2006 14:06:07 GMT w8ji@akorn.net wrote: > Absolutely nothing, neither electic nor magnetic, couplesthrough the > wall of a conductor more than several skin depths thick. Do 60 Hz magnetic fields penetrate RF coax since the conductor is not more than several skin depths thick? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224571 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Auto-Tuners with balanced antenna? References: Message-ID: Date: Sun, 21 May 2006 14:08:10 GMT Lew wrote: > I run a SGC ATU to my Dipole with ladder line with no problems Isn't that contrary to SGC's recommendations? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224572 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> Message-ID: Date: Sun, 21 May 2006 14:12:34 GMT Bob Miller wrote: > I have a 130 foot dipole, about 25' high in the middle, 20' at the > ends, fed with 47' of the Wireman's ladderline, going directly to the > 4-1 balun of an old mfj989c tuner. From everything I've read in this > thread, it shouldn't tune worth a darn on 40 meters, but I can get a > 1-1 swr match on 40, as well as every other band. That "1-1 swr" is on the coax between the tuner and the transmitter. The SWR on the ladder-line is probably around 12:1. > One of these days I might try Cecil's idea, a 100 foot feed of > ladderline, but I'd have to string about 50' of that back and forth to > make it work. Please see my other posting. Using a messenger string, tie wrap 20 inches of ladder-line to every 10 inches of string. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224573 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 15:02:48 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Doesn't the matchbox do the > > electrical tuning of the feedline instead of using fixed lengths as you > > are doing? > > If it's a Johnson Matchbox, it has a limited tuning range. > But for dipoles 1/2WL at the lowest frequency of operation, > feeding in the rough vicinity of the current maximum point > will work. For 80m and 40m, you might get by with 80 feet > of feedline. > > > I just dug out my Drake MN-2700 user manual and it says to use 135 foot > > long horizontal fed in the middle with 67 feet of ladder. Weird, this > > stuff is worse than making a pizza. > > If that is for 80m or 40m, the Drake must like very high > impedances. I just tacked on additional ladder line for a total of 91 feet, it's draped all over the place. The matchbox tunes more difficult on 75 M but tuned right up on 40. The matchbox controls are skewed quite a ways off the center point. tuning control is at 26 and match is about 15 so it does not seem to like this length any better. I could tack on another 15 feet but then I'd have to lay it on the ground which is not good. I could shorten up the original 67 feet to perhaps 50 plus but that would make it worse? The Drake MN2700 uses a 4 to 1 balun for matching ladder line. I use my Johnson KW matchbox for the ladder line. -- Email: dalej2@mac.com Article: 224574 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: 2.4 GHz Yagi References: <1148186964.790355.140740@i39g2000cwa.googlegroups.com> Message-ID: Date: Sun, 21 May 2006 09:40:14 -0500 I'd suggest it isnt worth attempting. The frequency change is more than 3:1 from the original TV use. There are a lot of simple 2.4GHz designs out there that are worth looking at. Cheers Bob VK2YQA pdrunen@aol.com wrote: > > Hi Group, > > I looking at convering a TV UHF antenna to 2.4 GHz, the antenna has a > yagi part with elements spaced every 3 inches and the elements are the > same lenght of about 3 inches. Article: 224575 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Multiband doublet feedline length Message-ID: References: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> Date: Sun, 21 May 2006 15:58:25 GMT On Sun, 21 May 2006 14:12:34 GMT, Cecil Moore wrote: >Bob Miller wrote: >> I have a 130 foot dipole, about 25' high in the middle, 20' at the >> ends, fed with 47' of the Wireman's ladderline, going directly to the >> 4-1 balun of an old mfj989c tuner. From everything I've read in this >> thread, it shouldn't tune worth a darn on 40 meters, but I can get a >> 1-1 swr match on 40, as well as every other band. > >That "1-1 swr" is on the coax between the tuner and the >transmitter. The SWR on the ladder-line is probably around 12:1. > >> One of these days I might try Cecil's idea, a 100 foot feed of >> ladderline, but I'd have to string about 50' of that back and forth to >> make it work. > >Please see my other posting. Using a messenger string, tie >wrap 20 inches of ladder-line to every 10 inches of string. If I were to use W7FG's 600-ohm line, would 100' still be a good length? bob k5qwg Article: 224576 of rec.radio.amateur.antenna From: "RST Engineering" References: <1148186964.790355.140740@i39g2000cwa.googlegroups.com> Subject: Re: 2.4 GHz Yagi Date: Sun, 21 May 2006 09:21:52 -0700 Message-ID: Is there a URL where this is discussed? Jim And, a small satellite TV dish is easy to convert to 2.4 > GHz. > > Jerry > Article: 224577 of rec.radio.amateur.antenna From: Me Subject: Re: Auto-Tuners with balanced antenna? References: Message-ID: Date: Sun, 21 May 2006 18:07:22 GMT In article , Cecil Moore wrote: > Lew wrote: > > I run a SGC ATU to my Dipole with ladder line with no problems > > Isn't that contrary to SGC's recommendations? Only if you believe that SGC, has a CLUE about how their autotuner works, and the design of the firmware that runs it............. Me Article: 224578 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: <50q072h0ell1qfeepqkn3mfrg20spe6v8b@4ax.com> Message-ID: Date: Sun, 21 May 2006 18:32:24 GMT Bob Miller wrote: > If I were to use W7FG's 600-ohm line, would 100' still be a good > length? I don't know. If you have EZNEC, it can tell you. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224579 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 19:54:36 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > I'll give the 100 ft a go and let you know. > > > > When you say wind the ladder line around a tag rope, I assume you mean > > to use ties around one wire of the ladder and make the loop maybe a foot > > in diameter or maybe 6 inches? Sort of a helix affair. Would that > > cause a problem with the ladder being so close to the turns? > > You are forming 100 ft. of ladder-line into a 50 ft. long helix. > The spacing on the turns will not be a problem as it will be > a very loosely wound helix. Tie a knot in the messenger string > every 10 inches. Anchor one point of the ladder-line to a knot > in the messenger string using black tie-wraps. Take 20 inches of > ladder-line and anchor it at the next knot down from the first knot. > That will give you one turn of the helix. Repeat until you have > a 100 foot feedline. If you didn't want to use tie-wraps, you > could tie the 10 inch spaced knots through the ladder-line every > 20 inches of ladder-line. I just dug out my Practical Wire Antennas book by John Heys, G3BDQ, RSGB 1989, P. 16 & 17 "centre-fed antennas using tuned feedlines", and it collaborates the information in my old ARRL 1960 handbook which says to calculate one half of the horizontal wire plus the feedline length and that total number should not equal certain critical lengths one of which is 160 feet on 3.6 Mhz, there are more. I hate to beat this to death, but frankly I don't think any of us has a clear understanding of this antenna. Dalej. -- Email: dalej2@mac.com Article: 224580 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Sun, 21 May 2006 20:47:25 GMT On Sun, 21 May 2006 01:12:16 GMT, Owen Duffy wrote: >... It certainly presents the >worst case feedline VSWR on 7MHz, the highest feedline voltage (>2500V >peak at 1kW), though the transmission line loss for 90' of 551 is only >0.6dB in the above scenario. When I read that in the clarity of a new day, I can see that is not correct as written, I should have said: It certainly presents the worst case feedpoint impedance at 7MHz, the highest feedpoint voltage (>2500V peak at 1kW), though the transmission line loss for 90' of 551 is only 0.6dB in the above scenario. (A shorter dipole may result in higher voltage along the feedline, and higher feedline loss, depending on the lengths of each of dipole and feedline.) Owen -- Article: 224581 of rec.radio.amateur.antenna From: Alan WA4SCA Subject: Re: Auto-Tuners with balanced antenna? Message-ID: <7vk172l0050bo0b4e8rm02n7mrlonn1r81@4ax.com> References: Date: Sun, 21 May 2006 20:59:04 GMT Ed, Take a look at http://www.hamware.de/index.html Just got back from Dayton, and the ones on display looked solidly built, though that is no indication of how well they actually work. Eham has some positive reviews of an earlier model. No personal experience. -- Alan WA4SCA Article: 224582 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Sun, 21 May 2006 16:07:22 -0500 Message-ID: <21360-4470D68A-1590@storefull-3257.bay.webtv.net> References: <1148204558.861148.41500@j55g2000cwa.googlegroups.com> Tom, W8JI wrote: "Absolutely nothing, neither electric nor magnetic, couples through the wall of a conductor several skin depths thick." That`s wrong for a "Faraday screen". Terman is right. At the bottom of page 38 of his 1955 edition he writes: "It is possible to shield electrostatic flux without simultaneously affecting the magnetic field by surrounding the space to be shielded with a conducting cage that is made in such a way as to provide no low-resistance path for the flow of eddy currents, while at the same time offering a metallic terminal upon which electrostatic flux lines can terminate." An example exists in the AM broadcast stations I`ve worked in. Every tower was coupled to its transmission line through a 1:1 air-core traansformer. Two identical single-layer solenoids sharing the same axis. Between the coils was a metal picket fence. One end of the pickets was firmly grounded to the coupling cabinet. The other end of all pickets was an open circuit. Electric lines of force were intercepted by the pickets and directly shorted to ground. However, the fences had no effect on the magnetic coupling between them because the open circuit at the ends of the pickets prevented circulating currents which would have opposed magnetic coupling according to Lenz`s law. Voila! Magnetic coupling but no electrostatic coupling between coils of a transformer. It`s time for W8JI to turn-off his misinformation machine. Best regards, Richard Harrison, KB5WZI Article: 224583 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Sun, 21 May 2006 21:50:32 GMT On Sun, 21 May 2006 19:54:36 GMT, "dale.j. " wrote: >In article , > Cecil Moore wrote: > > >I just dug out my Practical Wire Antennas book by John Heys, G3BDQ, >RSGB 1989, P. 16 & 17 "centre-fed antennas using tuned feedlines", and >it collaborates the information in my old ARRL 1960 handbook which says >to calculate one half of the horizontal wire plus the feedline length >and that total number should not equal certain critical lengths one of As has been noted in several posts, this is not a new approach. The approach seeks to avoid length combinations that result in the impedance maximums at desired operating frequencies, whether or not those impedance maximums are ok for the ATU. It is an approximation in several ways, including that it does not consider the velocity factor of the transmission line, it does not consider the effects of the environment on the impedance at the feed point of the radiator, it assumes that higher order modes are exactly harmonically related. So, even then, the lengths indicated as undesirable may have significant error incorporated. Let's look at an example: Consider a model of a 40m dipole of length 20.12m at 10m above average ground, and I want to use it at 28MHz with Wireman 551 feedline of 20m (or greater). The wavelength at 28MHz is 10.7m, so your method would suggest that 3*10.7 or 32.1m is a "total" length to avoid, meaning that a feedline of 32.1-20.12/2m or 22.04m is the feed length to avoid. At this "undesirable length", the model yields a load impedance of 82+j58 which should not be particularly troublesome to most tuners at 28MHz. In fact the corresponding modelled voltage maximum occurs with a feedline of 19.4m (not at 22.04m), so the method is 2.64m or 12% in error in this example. The next voltage maximum occurs at feedline length of 24.2m, so the forecast undesirable length is roughly in the middle of these two lengths, and about as far as you can get (ie the most error) from the modelled voltage maxima. >which is 160 feet on 3.6 Mhz, there are more. I hate to beat this to >death, but frankly I don't think any of us has a clear understanding of >this antenna. You don't understand it, so no one else does? I have got the picture. Owen -- Article: 224584 of rec.radio.amateur.antenna From: mzenier@eskimo.com (Mark Zenier) Subject: Re: HF broadcasting antennas Date: Sun, 21 May 2006 18:03:00 GMT Message-ID: References: <5s84k3-2id.ln1@remote.clifto.com> In article <5s84k3-2id.ln1@remote.clifto.com>, clifto wrote: >sipa wrote: >> First please excuse me for my bad english. > >1. Your English is far better than my Hungarian. I think .hr is Croatia. Mark Zenier mzenier@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com) Article: 224585 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: seperation in lie of a duplexer at 222 mhz band Date: Sun, 21 May 2006 22:13:32 -0000 Message-ID: <1271pgcl22ihl42@corp.supernews.com> References: <1148246239.775059.271390@u72g2000cwu.googlegroups.com> In article <1148246239.775059.271390@u72g2000cwu.googlegroups.com>, an old friend wrote: >haing gotten many of the peices of a 222 band repater and wanting to >put it on the air how much sepertion is required to avoid a paying the >price of a duplexer at 22 band That depends to some extent on the design of your receiver. Different designs have different RF-signal thresholds at which front-end desensitization will become a problem. A receiver with a broadly-tuned front end (e.g. some converted Motorola radios, most mobile ham rigs) is likely to be more prone to desense than a dedicated single-frequency receiver board having several stages of narrowly-tuned helical resonator in the RF chain. It'll also depend on how clean your transmitter is. Broadband noise and spurs from the transmitter can cause problems for the receiver by "swamping" the desired signal with noise, independent of whatever desensitization the main transmit signal causes to the receiver front-end. My old copy of ARRL's "FM and Repeaters" book (copyright 1972) suggests that approximately 58 dB of attenuation is required for a 600 kHz transmit/receive offset. They don't give a suggested figure for the wider 1.6 MHz offset used on the 222 band. According to the graphs in this book, achieving 58 dB of attenuation, on the 222 band, requires approximately 20 feet of vertical separation between antennas, or approximately 100 feet of horizontal separation, assuming unity-gain antennas (e.g. halfwave dipoles). You'd need greater horizontal separation when using antennas with gain over a halfwave. You might be able to get by with less vertical separation if using gain antennas, depending on the actual pattern, feedline radiation, local reflections, and so forth. You might want to Google around for articles which show a method for homebrewing a duplexer, using a length of surplus large-diameter hardline coaxial cable as the resonator. These have apparently been used for several years on the 6-meter band, and I recently saw a Heliax notch/pass resonator which was made for a local 2-meter repeater (it adds one additional section of receive filtering/isolation to a repeater which uses a single antenna and a commercially-built two-transmit-can, two-receive-can duplexer). The Q of such Heliax-based resonators is lower than that of conventional cans, and the insertion losses are higher. If you don't want to install a full-fledged duplexer and use a single antenna, you might try something like a pair of 222 antennas with 20 foot or more of vertical separation, plus one band-reject (or band-pass band-reject) Heliax resonator on each one. http://www.dallas.net/~jvpoll/dup6m/dup6m.html would be one place to start looking. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224586 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Sun, 21 May 2006 23:00:28 GMT In article , Owen Duffy wrote: > On Sun, 21 May 2006 19:54:36 GMT, "dale.j. " > wrote: > > >In article , > > Cecil Moore wrote: > > > > > > >I just dug out my Practical Wire Antennas book by John Heys, G3BDQ, > >RSGB 1989, P. 16 & 17 "centre-fed antennas using tuned feedlines", and > >it collaborates the information in my old ARRL 1960 handbook which says > >to calculate one half of the horizontal wire plus the feedline length > >and that total number should not equal certain critical lengths one of > > As has been noted in several posts, this is not a new approach. > > The approach seeks to avoid length combinations that result in the > impedance maximums at desired operating frequencies, whether or not > those impedance maximums are ok for the ATU. > > It is an approximation in several ways, including that it does not > consider the velocity factor of the transmission line, it does not > consider the effects of the environment on the impedance at the feed > point of the radiator, it assumes that higher order modes are exactly > harmonically related. > > So, even then, the lengths indicated as undesirable may have > significant error incorporated. > > Let's look at an example: > > Consider a model of a 40m dipole of length 20.12m at 10m above average > ground, and I want to use it at 28MHz with Wireman 551 feedline of 20m > (or greater). > > The wavelength at 28MHz is 10.7m, so your method would suggest that > 3*10.7 or 32.1m is a "total" length to avoid, meaning that a feedline > of 32.1-20.12/2m or 22.04m is the feed length to avoid. > > At this "undesirable length", the model yields a load impedance of > 82+j58 which should not be particularly troublesome to most tuners at > 28MHz. > > In fact the corresponding modelled voltage maximum occurs with a > feedline of 19.4m (not at 22.04m), so the method is 2.64m or 12% in > error in this example. The next voltage maximum occurs at feedline > length of 24.2m, so the forecast undesirable length is roughly in the > middle of these two lengths, and about as far as you can get (ie the > most error) from the modelled voltage maxima. > > >which is 160 feet on 3.6 Mhz, there are more. I hate to beat this to > >death, but frankly I don't think any of us has a clear understanding of > >this antenna. > > You don't understand it, so no one else does? I have got the picture. > > Owen > -- With all the J factoring ect I tend to get a bit intimidated. Then I go back to the books from years ago. I don't have EZnec. Dalej. -- Email: dalej2@mac.com Article: 224587 of rec.radio.amateur.antenna From: Roger Subject: Re: ARS License Numbers Message-ID: References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> Date: Sun, 21 May 2006 19:16:53 -0400 On Sat, 20 May 2006 15:15:39 -0700, "Sal M. Onella" wrote: > > > >> > I am quite sure that they all got their tickets with CW >> > required. And the problem stations on 75 are quite the same. Which >> > also proves nothing either way. >> >> it does prove that CW testing is at best poor proof of screening out >> bad ops > >There's no test for one important ham skill: typing. I didn't appreciate >how important it is until I learned that one of my pro-Morse buddies does >all of his sending with a computer. (He can send with a key but doesn't >know where his is.) He says he copies with the computer, too, although he >can follow along with the audio. > >I asked around and found this practice is far from rare; I'm not sure >"common" is the right word, though. > >We also might want to test for basic language skills, including punctuation. >While it's not always true, the disagreeable transmissions (and NG posts) >often make the speakers/writers sound pretty ignorant. In that case how about testing for personality traits as well as anti-social and anti-authoritarian behavior? <:-)) Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com > Article: 224588 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1148204558.861148.41500@j55g2000cwa.googlegroups.com> <21360-4470D68A-1590@storefull-3257.bay.webtv.net> Subject: Re: FIGHT? Here is another W8JI myth bone! Message-ID: Date: Sun, 21 May 2006 20:07:58 -0400 Richard, "this can't be" because "gurus" know otherwise. Why do you hate Tom? You don't like anything he says on his "myth overturning" web pages. He describes in a such detail and explains that "shield is an antenna" - why don't you get it? :-)))) According to Tom, RF gets induced on the outside "wire" of the shield, then it crolls to the "inside" wire of the shield around the edge of the tubing and sees another wire and jumps over, and then to coax. If tubing or shield was the antenna, then it would receive DX and near field signals the same way. The fact that shield is shielding the near field signals should make any guru wonder. There was ZS1 on TopBand reflector reporting that he used shielded loop and other loop antennas, and shielded loop was the only one that suppressed the local TV birdies. Tom "explained" to him "how things work" and he apologized that he did not mean to have this as an example of what I was saying. There are other examples where shield "doesn't shield" - like link coupling made of coax with end shield open and center conductor soldered to the shield. As I mentioned I have magnetothermia machine that produces about 200W from single shielded loop, according to Tom, it should be frying the coax in the gap, with all that RF power trying to make the corner :-) There is more nonsense on his web site. 73 Yuri, K3BU "Richard Harrison" wrote in message news:21360-4470D68A-1590@storefull-3257.bay.webtv.net... > Tom, W8JI wrote: > "Absolutely nothing, neither electric nor magnetic, couples through the > wall of a conductor several skin depths thick." > > That`s wrong for a "Faraday screen". > > Terman is right. At the bottom of page 38 of his 1955 edition he writes: > "It is possible to shield electrostatic flux without simultaneously > affecting the magnetic field by surrounding the space to be shielded > with a conducting cage that is made in such a way as to provide no > low-resistance path for the flow of eddy currents, while at the same > time offering a metallic terminal upon which electrostatic flux lines > can terminate." > > An example exists in the AM broadcast stations I`ve worked in. Every > tower was coupled to its transmission line through a 1:1 air-core > traansformer. Two identical single-layer solenoids sharing the same > axis. Between the coils was a metal picket fence. One end of the pickets > was firmly grounded to the coupling cabinet. The other end of all > pickets was an open circuit. Electric lines of force were intercepted by > the pickets and directly shorted to ground. However, the fences had no > effect on the magnetic coupling between them because the open circuit at > the ends of the pickets prevented circulating currents which would have > opposed magnetic coupling according to Lenz`s law. > > Voila! Magnetic coupling but no electrostatic coupling between coils of > a transformer. > > It`s time for W8JI to turn-off his misinformation machine. > > Best regards, Richard Harrison, KB5WZI > Article: 224589 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: FIGHT? Here is another W8JI myth bone! References: <1148204558.861148.41500@j55g2000cwa.googlegroups.com> <21360-4470D68A-1590@storefull-3257.bay.webtv.net> Message-ID: Date: Mon, 22 May 2006 00:35:42 GMT Richard, Think again about what you wrote. The "Faraday screen" is full of openings between the wires of the picket fence. There is no evidence that anything magnetic or electric penetrates the walls of the conductors beyond a very shallow layer. Terman certainly did not deny the existence of skin effect that keeps the fields out of the interior of conductors. 73, Gene W4SZ Richard Harrison wrote: > Tom, W8JI wrote: > "Absolutely nothing, neither electric nor magnetic, couples through the > wall of a conductor several skin depths thick." > > That`s wrong for a "Faraday screen". > > Terman is right. At the bottom of page 38 of his 1955 edition he writes: > "It is possible to shield electrostatic flux without simultaneously > affecting the magnetic field by surrounding the space to be shielded > with a conducting cage that is made in such a way as to provide no > low-resistance path for the flow of eddy currents, while at the same > time offering a metallic terminal upon which electrostatic flux lines > can terminate." > > An example exists in the AM broadcast stations I`ve worked in. Every > tower was coupled to its transmission line through a 1:1 air-core > traansformer. Two identical single-layer solenoids sharing the same > axis. Between the coils was a metal picket fence. One end of the pickets > was firmly grounded to the coupling cabinet. The other end of all > pickets was an open circuit. Electric lines of force were intercepted by > the pickets and directly shorted to ground. However, the fences had no > effect on the magnetic coupling between them because the open circuit at > the ends of the pickets prevented circulating currents which would have > opposed magnetic coupling according to Lenz`s law. > > Voila! Magnetic coupling but no electrostatic coupling between coils of > a transformer. > > It`s time for W8JI to turn-off his misinformation machine. > > Best regards, Richard Harrison, KB5WZI > Article: 224590 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Mon, 22 May 2006 00:42:24 GMT dale.j. wrote: > I just dug out my Practical Wire Antennas book by John Heys, G3BDQ, > RSGB 1989, P. 16 & 17 "centre-fed antennas using tuned feedlines", and > it collaborates the information in my old ARRL 1960 handbook which says > to calculate one half of the horizontal wire plus the feedline length > and that total number should not equal certain critical lengths one of > which is 160 feet on 3.6 Mhz, there are more. I hate to beat this to > death, but frankly I don't think any of us has a clear understanding of > this antenna. EZNEC can solve the problem. EZNEC was not available to the 1960 hams. Let's take a 130 foot dipole on 3.6 MHz with 95 feet of 450 ohm ladder-line with a velocity factor of 0.9. 65+95=160 The impedance seen by the tuner is 100-j400. Virtually every tuner in the world should be able to match that impedance. The antenna system is resonant around 4 MHz. The free demo version of EZNEC is available at: http://www.eznec.com How does the 1960 ARRL handbook handle velocity factor? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224591 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Mon, 22 May 2006 00:46:11 GMT dale.j. wrote: > With all the J factoring ect I tend to get a bit intimidated. Then I go > back to the books from years ago. I don't have EZnec. The free demo version will do what you need done. It is available at: http://www.eznec.com -- 73, Cecil http://www.qsl.net/w5dxp Article: 224592 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Mon, 22 May 2006 01:23:08 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > With all the J factoring ect I tend to get a bit intimidated. Then I go > > back to the books from years ago. I don't have EZnec. > > The free demo version will do what you need done. > It is available at: http://www.eznec.com OSX don't do executables and I'm not switching to windows. I'll just struggle along with my musty old books. Dalej. -- Email: dalej2@mac.com Article: 224593 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: Elimination of CW is a loss in the number of ways we can communicate with other. Date: Sun, 21 May 2006 22:46:03 -0400 Message-ID: <12729e4e160k0f5@corp.supernews.com> References: <1147549161.064623.59130@j33g2000cwa.googlegroups.com> <1147586170.894157.292250@d71g2000cwd.googlegroups.com> <38c8.gop.17.1@news.alt.net> <1147832357.964390.122730@i40g2000cwc.googlegroups.com> <1148093850.852066.18100@u72g2000cwu.googlegroups.com> I intend to post the cartoon on my door. Several in my department will understand. 73 Mac N8TT s:p1j1729noc9djlhlbdk15q4q95asf8kea9@4ax.com... > The thread-ending clincher: if it weren't for cw, no one would understand > today's (5/21/2006) Foxtrot cartoon. > > -- Larry > Article: 224594 of rec.radio.amateur.antenna From: Murray Neece Subject: Re: ARS License Numbers and idiots galore Date: Sun, 21 May 2006 22:11:10 -0500 Message-ID: <1272athq7lvn71f@corp.supernews.com> References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> I love it!! You guys will never change. Glad you got to see me..73 and all that. K5MDM Murray Article: 224595 of rec.radio.amateur.antenna Subject: Grounding a metal roof From: "AG4QC" Date: Sun, 21 May 2006 23:48:59 -0500 Message-ID: <1148272981_5573@sp6iad.superfeed.net> I am having a metal roof put on the house and shop. The installer said it isn't required to be grounded. The city inspector said the same thing. Is that really true? I'm thinking of running a #8 from the roof to my common ground. Does that make sense? Joe Loucka AG4QC ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- Article: 224596 of rec.radio.amateur.antenna Date: Mon, 22 May 2006 15:08:27 +1000 From: spears Subject: highest gain hf antenna in the world Message-ID: <44714748_1@news.iprimus.com.au> I was wondering what is the highest gain hf antenna thats operational anywhere in the world? Secondly what is the gain. Peter Article: 224597 of rec.radio.amateur.antenna From: "Lee" References: <1148246239.775059.271390@u72g2000cwu.googlegroups.com> <1271pgcl22ihl42@corp.supernews.com> <1148266485.066932.188610@i39g2000cwa.googlegroups.com> Subject: Re: seperation in lie of a duplexer at 222 mhz band Message-ID: Date: Mon, 22 May 2006 05:58:01 GMT I see that English isn`t your mother tongue then !!!.......or are you just kidding??.... ;-) Lee......G6ZSG..... "an_old_friend" wrote in message news:1148266485.066932.188610@i39g2000cwa.googlegroups.com... > > Dave Platt wrote: > > In article <1148246239.775059.271390@u72g2000cwu.googlegroups.com>, > > an old friend wrote: > > > > >haing gotten many of the peices of a 222 band repater and wanting to > > >put it on the air how much sepertion is required to avoid a paying the > > >price of a duplexer at 22 band > cut for brevity > > My old copy of ARRL's "FM and Repeaters" book (copyright 1972) > > suggests that approximately 58 dB of attenuation is required for a 600 > > kHz transmit/receive offset. They don't give a suggested figure for > > the wider 1.6 MHz offset used on the 222 band. > > > > According to the graphs in this book, achieving 58 dB of attenuation, > > on the 222 band, requires approximately 20 feet of vertical separation > > between antennas, or approximately 100 feet of horizontal separation, > > assuming unity-gain antennas (e.g. halfwave dipoles). You'd need > > greater horizontal separation when using antennas with gain over a > > halfwave. You might be able to get by with less vertical separation > > if using gain antennas, depending on the actual pattern, feedline > > radiation, local reflections, and so forth. > ty for that given the proposed is a pair of disused grain silos 80 feet > a part I was thinking horizontal sepertion (frankly had not considered > vertical at all or i would have made that > > > > You might want to Google around for articles which show a method for > > homebrewing a duplexer, using a length of surplus large-diameter > > hardline coaxial cable as the resonator. These have apparently been > > used for several years on the 6-meter band, and I recently saw a > > Heliax notch/pass resonator which was made for a local 2-meter > > repeater (it adds one additional section of receive > > filtering/isolation to a repeater which uses a single antenna and a > > commercially-built two-transmit-can, two-receive-can duplexer). The Q > > of such Heliax-based resonators is lower than that of conventional > > cans, and the insertion losses are higher. > > > > If you don't want to install a full-fledged duplexer and use a single > > antenna, you might try something like a pair of 222 antennas with 20 > > foot or more of vertical separation, plus one band-reject (or > > band-pass band-reject) Heliax resonator on each one. > > > > http://www.dallas.net/~jvpoll/dup6m/dup6m.html would be one place to > > start looking. > I had read something of that but have never been any good at cuting > stuff right (i end up with lots of scrap > > i have just hearing folks with with radio that have some 22 band (a > kenwood tribander has been popular round here) and no reapters localy > that use it I am planing on trying to put together a decent repater > that work at least out then goping after I ge it u and let be know at > that point it exists maybe some folks that could help with hombrewing a > duplexer will step up to improve the system > > ty for the info > > > > -- > > Dave Platt AE6EO > > Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior > > I do _not_ wish to receive unsolicited commercial email, and I will > > boycott any company which has the gall to send me such ads! > Article: 224598 of rec.radio.amateur.antenna From: "DAVID BROWNE" Subject: can i use this for satalite working A270-10S Cushcraft 2m/70cm 5 el Yagi Message-ID: Date: Mon, 22 May 2006 06:36:20 GMT A270-10S Cushcraft 2m/70cm 5 el Yagi * Frequency 144-148MHz, 430-450MHz * Elements 5 ea. band * Power 350W * Forward Gain10dB * Front-to-back 20, 18dBi * SWR (typ) 1.2:1 * Bandwidth >4MHz, >10MHz * Boom length 1.9m * Longest element 102.4cm * Turning radius 1.8m * Mast Size 32-51mm * Wind load 0.07 * Weight 0.81kg This antenna can be mounted in either vertical or horizontal polarisation. It is perfect where space is tight and dual-band operation is required. The harmonic relationship of 2m and 70cm allows clean radiation patterns with minimal interaction. if i can dose it want to be mounted vertical or horizontal polarisation Article: 224599 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Mon, 22 May 2006 09:11:21 GMT In article , Dan Richardson <> wrote: > On Mon, 22 May 2006 01:23:08 GMT, "dale.j. " > wrote: > > >OSX don't do executables and I'm not switching to windows. I'll just > >struggle along with my musty old books. > > You can lead a hourse to water but you can't ............... What did you do before EZnec? -- Email: dalej2@mac.com Article: 224600 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Mon, 22 May 2006 09:24:10 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > I just dug out my Practical Wire Antennas book by John Heys, G3BDQ, > > RSGB 1989, P. 16 & 17 "centre-fed antennas using tuned feedlines", and > > it collaborates the information in my old ARRL 1960 handbook which says > > to calculate one half of the horizontal wire plus the feedline length > > and that total number should not equal certain critical lengths one of > > which is 160 feet on 3.6 Mhz, there are more. I hate to beat this to > > death, but frankly I don't think any of us has a clear understanding of > > this antenna. > > EZNEC can solve the problem. EZNEC was not available to the > 1960 hams. Let's take a 130 foot dipole on 3.6 MHz with > 95 feet of 450 ohm ladder-line with a velocity factor of > 0.9. 65+95=160 The impedance seen by the tuner is 100-j400. > Virtually every tuner in the world should be able to match > that impedance. The antenna system is resonant around 4 MHz. > The free demo version of EZNEC is available at: > http://www.eznec.com > > How does the 1960 ARRL handbook handle velocity factor? In Heys book circa 1989, he says "The velocity factor is only of significance in certain antenna types, for example those requiring quarter-wave 'stubs'. Such stubs are needed for the four -element collinear antenna illustrated in Fig 21 and described later. Open wire lines have a velocity factor of about 0.975 which means that a quarter-wavelength stub at 7 Mhz will be 10in. (25cm) shorter than a basic electrical quarter-wave-length." In my old dusty musty ARRL 1960 and 1983 antenna handbooks I did not find any reference to velocity factor in using this type of antenna. Dalej. -- Email: dalej2@mac.com Article: 224601 of rec.radio.amateur.antenna From: =?utf-8?b?Sm9uIEvDpXJlIEhlbGxhbg==?= Subject: Re: 2.4 GHz Yagi Date: 22 May 2006 15:43:13 +0200 Message-ID: <1md5e6rx8u.fsf@persaunet.uninett.no> References: <1148186964.790355.140740@i39g2000cwa.googlegroups.com> Bob Bob writes: > I'd suggest it isnt worth attempting. The frequency change is more > than 3:1 from the original TV use. > > There are a lot of simple 2.4GHz designs out there that are worth > looking at. Here are some cool ones build using Chinese cookware and USB Wi-Fi adapters: http://www.usbwifi.orcon.net.nz/ E.g. this one: http://www.usbwifi.orcon.net.nz/usbscoop.jpg 73 LA4RT Jon Article: 224602 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: <8re372ldsqnuijojl3rhglc333in021umj@4ax.com> Message-ID: Date: Mon, 22 May 2006 14:10:19 GMT In article <8re372ldsqnuijojl3rhglc333in021umj@4ax.com>, Dan Richardson <> wrote: > On Mon, 22 May 2006 09:11:21 GMT, "dale.j. " > wrote: > > >In article , > > Dan Richardson <> wrote: > > > >> On Mon, 22 May 2006 01:23:08 GMT, "dale.j. " > >> wrote: > >> > >> >OSX don't do executables and I'm not switching to windows. I'll just > >> >struggle along with my musty old books. > >> > >> You can lead a hourse to water but you can't ............... > > > > > >What did you do before EZnec? > > Made a lot of mistakes that I don't do now. > > > > In my many years I have come to a conclusion that one > useless man is a shame, two is a law firm, and three > or more is a congress. - John Adams > > email: k6mhearrlnet > http://www.k6mhe.com/ Well, I downloaded it on my shop machine and when I get around to it I'll take a look as long as I don't have to spend a lot of time learning it's operation. I'm going jogging now. 73 Dale PS Nice web site Dan. -- Email: dalej2@mac.com Article: 224603 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <44714748_1@news.iprimus.com.au> Subject: Re: highest gain hf antenna in the world Message-ID: Date: Mon, 22 May 2006 10:12:45 -0400 "spears" wrote in message news:44714748_1@news.iprimus.com.au... >I was wondering what is the highest gain hf antenna thats operational >anywhere in the world? Secondly what is the gain. > > Peter It is most likely the huge dish in Arecibo, Puerto Rico. Close by would be the HARP system in Alaska. Then the curtain arrays used by broadcast stations. Then the Rhombics, then the rest. -- Yuri Blanarovich, K3BU, VE3BMV Article: 224604 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Mon, 22 May 2006 10:04:55 -0500 Message-ID: <23154-4471D317-1504@storefull-3254.bay.webtv.net> References: <1148301147.519366.35860@j73g2000cwa.googlegroups.com> Gene Fuller wrote: "Terman certainly did not deny the existence of skin effect that keeps fields out of the interior of conductors.' true. The point is, shielding from magnetic fields is different from electric fields. On page 35 of his 1955 edition, Terman writes: "Magnetic flux in attempting to pass through a shield (copper or aluminum) induces voltage in the shield which gives rise to eddy currents. These eddy currents oppose the action of the flux, and in large measure prevent its penetration through the shield." On page 38, Terman writes: "Electrostatic shielding is obtained by enclosing free space to be shielded by a conducting surface." On page 45, is problem 2-45 which contains an illustration of a grid of open-circuit wires which "will provide electrostatic shielding without magnetic shielding---." This works just like the picket fences used in broadcast stations to inhibit harmonic transmission. Terman did not make this stuff up. It was already in wide use at the time. Best regards, Richard Harrison, KB5WZI Article: 224605 of rec.radio.amateur.antenna From: "laborkei" Subject: Hamvention: Amateur Radio Manufacturers and Unfair Pricing... Message-ID: <1mlcg.51373$Kn4.38159@bignews2.bellsouth.net> Date: Mon, 22 May 2006 12:08:47 -0400 Amateur Radio Manufacturers and unfair pricing! Here I sit the day after Dayton, calling around to all the dealers looking for a HF Transceiver. There were some fantastic prices offered on equipment (As much as $500 off list), and the dealers are back to charging full price today. I am told by the dealers I called, that the Manufacturers were making deals with them so they could sell there inventories much cheaper, and the orders had to be taken at Dayton. Today, the day after when most of these orders had not even shipped yet, they are back up to full retail price. To be fair, Manufacturers should allow these prices for a time period after Dayton to give other Amateurs who could not drive to Dayton an opportunity to get the same deals. I think we should all write to them and let them know how we feel. This is unfair ! Article: 224606 of rec.radio.amateur.antenna From: Paul Rubin Subject: Re: Hamvention: Amateur Radio Manufacturers and Unfair Pricing... References: <1mlcg.51373$Kn4.38159@bignews2.bellsouth.net> Date: 22 May 2006 09:30:02 -0700 Message-ID: <7xirnyyqd1.fsf@ruckus.brouhaha.com> "laborkei" writes: > I think we should all write to them and let them know how we feel. This is > unfair ! Why not just vote with your wallet? Article: 224607 of rec.radio.amateur.antenna From: "Al - VA3KAI" References: Subject: Re: Multiband doublet feedline length Message-ID: Date: Mon, 22 May 2006 12:23:05 -0400 Cecil, I read the postings regularly for new ideas on antennas and feedlines. This recent posting with your ladder-line physical shortening idea is just the solution I was searching for to reduce my ~65' of 300 ohm ladder-line to stand-off my 40' tower and keep it out of my house. Now I can add a coax RF choke loop at the base of my ladder-line feeder (still outside) and feed the rest of the coax into the basement to my shack. I'll likely use knotted black dacron line for the stringer/messenger support. The antenna is an inverted 204' G5RV - any suggestions on how many RG-8X turns and what diameter choke loop to use for mostly 160, 80 and 40 metre band operations with this antenna - I was thinking about 8-9 turns on a 9" loop? I plan to have it about 37' up with the ends dropping down to 20'. I know it will be mostly a cloud-burner at this height, but it is the best I can do given my tower height and tree availability and it will get me on 160M. Thanks....... Al, va3kai "Cecil Moore" wrote in message news:z8_bg.13144$fb2.7760@newssvr27.news.prodigy.net... > dale.j. wrote: >> I'll give the 100 ft a go and let you know. >> >> When you say wind the ladder line around a tag rope, I assume you mean to >> use ties around one wire of the ladder and make the loop maybe a foot in >> diameter or maybe 6 inches? Sort of a helix affair. Would that cause a >> problem with the ladder being so close to the turns? > > You are forming 100 ft. of ladder-line into a 50 ft. long helix. > The spacing on the turns will not be a problem as it will be > a very loosely wound helix. Tie a knot in the messenger string > every 10 inches. Anchor one point of the ladder-line to a knot > in the messenger string using black tie-wraps. Take 20 inches of > ladder-line and anchor it at the next knot down from the first knot. > That will give you one turn of the helix. Repeat until you have > a 100 foot feedline. If you didn't want to use tie-wraps, you > could tie the 10 inch spaced knots through the ladder-line every > 20 inches of ladder-line. > -- > 73, Cecil http://www.qsl.net/w5dxp Article: 224608 of rec.radio.amateur.antenna From: "Michael Tope" References: <1148204558.861148.41500@j55g2000cwa.googlegroups.com> <21360-4470D68A-1590@storefull-3257.bay.webtv.net> <%5kcg.95$vQ5.31@fe10.lga> Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Mon, 22 May 2006 09:49:23 -0700 Message-ID: <_Zudnd8ToMgMduzZnZ2dnUVZ_v6dnZ2d@comcast.com> "Yuri Blanarovich" wrote in message news:%5kcg.95$vQ5.31@fe10.lga... >> RF current "makes the corner" around to the outside surface of the >> shield in coax all the time. If it didn't we wouldn't need choke >> balun's. > > We need RF chokes and baluns to supress curents induced on the shield from > the unbalance at the antenna feedpoint. Actually what oftentimes happens with a coax feed is that the RF current leaving the inside of the feedline shield can flow in two directions. It can flow down the antenna element half connected to the shield (desired path), or it can flow down the outside of the shield (undesired path). The electrons are dumb, all they are looking for is the path of least resistance. They can't tell that the metal surface on the outside of the coax isn't supposed to be part of the antenna. The only way to keep current from flowing down the shield is make the antenna element-half connected to the shield look like a lower impedance than the outside of the shield. If you place ferrite beads around the outside of the shield, this will raise the impedance of the shield path, thereby diverting the bulk of the RF current into the element-half and off of the shield's outside surface. > Sooo, according to W8JI "teachings", RF current gets induced onto the > outside surface of tubing, then crolls around the edges and goes inside > the tubing? As per K4FMX's comments, this can only happen if there is a center conductor inside the tubing, or if the tubing diameter is greater than ~1/2 wavelength in diameter, otherwise the inside of the tubing looks like a circular waveguide beyond cutoff. This is why coax of a given diameter becomes useless above a certain upper frequency limit. Once the I.D. of the coax becomes a significant fraction of a wavelength in diameter, the coax will start to support propagation of waveguide modes (e.g. non-TEM modes). At HF frequencies, even large diameter tubing is well beyond waveguide cutoff, so there is no concern about "corking" open tubing with no center conductor (it corks itself). 73, Mike W4EF..................................................... > Sooo, we should cork the elements, or the current will get confused inside > of dark tubing elements, Eh? > Any formulas to calculate the resonance of such "antenna"?? > Article: 224609 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Re: can i use this for satalite working A270-10S Cushcraft 2m/70cm 5 el Yagi Date: Mon, 22 May 2006 11:51:13 -0500 Message-ID: References: With a couple of caveats, yes, you can use it for satellite work. 1. Rear mount it, don't shoot through a metal mast. 2. Polarization: for LEOs won't matter (Low Earth Orbit). Since there aren't any HEOs right now, do whatever might give you dual use, e.g., if you want to work the occasional SSB contact then mount them for horizontal polarization. If, on the other hand, you want some increased FM repeater coverage, mount them for vertical polarization. As far as the LEOs go, polarization won't be a real factor. 3. Chances are neither antenna comes even close to claimed gain. It won't matter for the LEO, they are good enough. Some of the best fun you can currently have on satellites would be dramatically improved with a 2m preamp. Do yourself a favor and mount it out at the antenna, not after 2 or 3 dB of feedline loss in front of it. The mode B VUSAT works really well. Lots of fun to be had on it. ISS also works well (International Space Station). Old AO-7 still works (after being on an extended vacation for a decade or so) nicely on mode B, WHEN IT IS IN SUNLIGHT (batteries are shot)). Any bird that you work that has a 70cm downlink (your received side) will require a preamp unless you have no feedline loss at all. In summary, the antenna will work. Make sure to keep your feedline losses as low as possible. Nothing less than LMR-400 will do if you have any significant length of run to the antennas from the shack. (25' or more). Preamps at the antenna will make a night and day difference. They are the SINGLE thing you can do that will give the biggest bang for the buck. I recommend the SSB Electronics preamps as they are rugged, well built and well protected. Have fun. My sat setup: 2m/70cm nested quads (5el-2m/8 el-70cm), vertical polarization, mast mounted gasfet preamps 70cm 14.2 dBc circlularly polarized (RHC) crossed yagi M2 2m Egg Beater 3' parabolic dish for 2.4 gig, antenna mounted LNA down-converter. All antennas fed with 80' of LMR-400. AZ/EL rotors: G-800 AZ, Yaesu Elevation Rotor. 73, ...hasan, N0AN "DAVID BROWNE" wrote in message news:EZccg.6989$BD2.5190@newsfe4-win.ntli.net... > A270-10S Cushcraft 2m/70cm 5 el Yagi > * Frequency 144-148MHz, 430-450MHz * Elements 5 ea. band * Power 350W * > Forward Gain10dB * Front-to-back 20, 18dBi * SWR (typ) 1.2:1 * Bandwidth > >4MHz, >10MHz * Boom length 1.9m * Longest element 102.4cm * Turning > >radius > 1.8m * Mast Size 32-51mm * Wind load 0.07 * Weight 0.81kg > This antenna can be mounted in either vertical or horizontal polarisation. > It is perfect where space is tight and dual-band operation is required. > The harmonic relationship of 2m and 70cm allows clean radiation patterns > with minimal interaction. > > > if i can dose it want to be mounted vertical or horizontal polarisation > > Article: 224610 of rec.radio.amateur.antenna From: You Subject: Re: highest gain hf antenna in the world References: <44714748_1@news.iprimus.com.au> Message-ID: Date: Mon, 22 May 2006 17:12:38 GMT In article , "Yuri Blanarovich" wrote: > It is most likely the huge dish in Arecibo, Puerto Rico. Arecibo ISN"T an "HF" antenna......... Article: 224611 of rec.radio.amateur.antenna From: "kd5sak" References: <44714748_1@news.iprimus.com.au> Subject: Re: highest gain hf antenna in the world Message-ID: <9Imcg.31806$4L1.3730@newssvr11.news.prodigy.com> Date: Mon, 22 May 2006 17:40:21 GMT "You" wrote in message news:You-F7F432.09131822052006@netnews.worldnet.att.net... > In article , > "Yuri Blanarovich" wrote: > >> It is most likely the huge dish in Arecibo, Puerto Rico. > > Arecibo ISN"T an "HF" antenna......... Just for the heck of it , I did a little internet check on Arecibo and found the following info; ""Full operation of the facility ideally requires three frequency bands, near 3.175, 5.1, and 8.175 mhz." Harold KD5SAK Article: 224612 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: <8re372ldsqnuijojl3rhglc333in021umj@4ax.com> Message-ID: Date: Mon, 22 May 2006 19:09:52 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > Well, I downloaded it on my shop machine and when I get around to it > > I'll take a look as long as I don't have to spend a lot of time learning > > it's operation. I'm going jogging now. > > I'm sending you the EZNEC file for a 127' dipole with > 100' of 450 ohm ladder-line used on 3.6 MHz. It obeys > the 20 segment limit for the EZNEC demo. Thanks Cecil, I downloaded it on my G5 and saved it to my AMD XP machine in the workshop via my network. I did run it, but I'm going to have to spend some time with it. I'll take Dannys advice and download Roys getting started. 73 Dale -- Email: dalej2@mac.com Article: 224613 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Mon, 22 May 2006 19:12:42 GMT In article , Cecil Moore wrote: > dale.j. wrote: > > What did you do before EZnec? > > I remember my "Elmer" in the 50's adding extra > lengths of open-wire line on certain bands for > his 80m dipole. He said he did it to make his > Harvey Wells Band-Master Deluxe happy. I don't > recall him owning an SWR meter but he did have > a 6C4 homebrew GDO and a sensing loop for locating > current maximum points on the open-wire line. The > transformed impedance is lowest at the current > maximum point. > > When I was a Novice, every time I changed bands > from 40m to 80m, I would let my coax-fed dipole > down and jumper across two insulators. That was > the extent of my knowledge half a century ago. Seems like the Harvey Zmatch was more narrow tuning than the Johnson. -- Email: dalej2@mac.com Article: 224614 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: highest gain hf antenna in the world Date: Mon, 22 May 2006 19:56:44 -0000 Message-ID: <12745rs4pepag62@corp.supernews.com> References: <44714748_1@news.iprimus.com.au> <1148327168.199001.5220@38g2000cwa.googlegroups.com> In article <1148327168.199001.5220@38g2000cwa.googlegroups.com>, n3ox.dan@gmail.com wrote: >Seems like Arecibo might have around 36dB gain at 28MHz where it is a >28 wavelength dish, at least according to scaling numbers I found on a >random webpage. > >Not bad. Seems that a 3.5 wavelength dish (3.5MHz Arecibo) still has a >bit of gain too. 15dB? > >I wish I had 15dBd gain on 3.5MHz... don't exactly want it straight up, >though. That's OK. Just hoist up one mountain, lower the other, and rotate the whole dish/valley onto its side. Paul Bunyan would have thought nothing of it. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224615 of rec.radio.amateur.antenna From: Pete Connors Subject: Re: Auto-Tuners with balanced antenna? Message-ID: References: <7vk172l0050bo0b4e8rm02n7mrlonn1r81@4ax.com> Date: Mon, 22 May 2006 23:09:09 GMT On Sun, 21 May 2006 20:59:04 GMT, Alan WA4SCA wrote: >Ed, > >Take a look at http://www.hamware.de/index.html Just got back from >Dayton, and the ones on display looked solidly built, though that is >no indication of how well they actually work. Eham has some positive >reviews of an earlier model. No personal experience. I am just about to install a hamware AT-502 in my back garden to tune a 67ft doublet fed with ladder line. On 1.8MHz (and sometimes on 3.5 & 7MHz) I'll be using the ASU-502 accessory switch, strapping the feeders together and tuning it as a T against a crappy ground . I'll let youse all know how it works out. Pete, G4PLZ -- Pete Article: 224616 of rec.radio.amateur.antenna From: ml Subject: sgc dipole? Message-ID: Date: Mon, 22 May 2006 23:19:25 GMT hi I was wondering a few things i read about in my sgc tuner manual about dipoles a) they say or sorta recomend that if your making a simple horiz ctr fed dipole, it's 'best' to have one leg longer why is that 'a good idea' what happens that makes this sorta advisable b) they recomend the longer leg to be the rf 'ground'' side , really confused as to why, my gut would tell me to make the hot side the longest leg so i am confused can anyone help me understand the above, i kinda understand how the wave looks on a regular horizontal ctr fed dipole is any help appreciated Article: 224617 of rec.radio.amateur.antenna From: "Brenda Ann" Subject: Re: get help Date: Tue, 23 May 2006 08:41:02 +0900 Message-ID: References: <1148340733.169536.23730@38g2000cwa.googlegroups.com> "an_old_friend" wrote in message news:1148340733.169536.23730@38g2000cwa.googlegroups.com... > > Jay wrote: >> I put the ball to a metal grinder and I could easily see an outer F layer >> and then the E layer. I couldn't find a D layer, but it was dark outside > troll > I'm not so sure he's a troll.. it's a funny routine, and probably is meant as such. We really need something to lighten up this NG a little. :) Article: 224618 of rec.radio.amateur.antenna From: ml Subject: Re: highest gain hf antenna in the world References: <44714748_1@news.iprimus.com.au> <9Imcg.31806$4L1.3730@newssvr11.news.prodigy.com> Message-ID: Date: Mon, 22 May 2006 23:51:45 GMT > > Just for the heck of it , I did a little internet check on Arecibo and found > the following info; > ""Full operation of the facility ideally requires three frequency bands, > near 3.175, 5.1, and 8.175 mhz." > > Harold > KD5SAK < Subject: Variable coax length? Message-ID: References: Date: Mon, 22 May 2006 19:57:49 -0400 >Did you take a look at the information on my web page at: > >http://www.qsl.net/w5dxp/notuner.htm Can you make that work using coax instead of open wire? -- 73 for now Buck N4PGW Article: 224620 of rec.radio.amateur.antenna From: "Caveat Lector" References: Subject: Re: Is the little ball on top of my antenna the ionsphere? Message-ID: Date: Mon, 22 May 2006 17:11:29 -0700 Jay -- wrong approach Propagation is conrolled by the Palos Verdes Sundancers see URL: http://www.ve1dx.net/Stories/story109.html -- CL -- I doubt, therefore I might be ! "Jay" wrote in message news:jOrcg.651$Sf2.175@newsread1.news.pas.earthlink.net... >I put the ball to a metal grinder and I could easily see an outer F layer > and then the E layer. I couldn't find a D layer, but it was dark outside > and there's not supposed to be a D layer at night. Neat how antenna's can > be manufactured to do that. > > Just passed my tech and General on Sunday so I'll be on the bands as > soon as I find out my callsign and get an ionsphere for my antenna. I > destroyed the old one on the grinder and I hear you need a good ionsphere > to shoot good skip and hear far away stations. Reception has been really > shitty lately without the ionsphere. I looked through the last 4 issues of > QST and I couldn't find anyone selling ionsphere's. Where can I get one, > or do I have to buy a whole new antenna? > > Thanks, Jay > Article: 224621 of rec.radio.amateur.antenna Subject: Re: Is the little ball on top of my antenna the ionsphere? From: Ed References: Message-ID: Date: 23 May 2006 00:28:21 GMT Jay wrote in news:jOrcg.651$Sf2.175@newsread1.news.pas.earthlink.net: > I put the ball to a metal grinder and I could easily see an outer F > layer and then the E layer. I couldn't find a D layer, but it was > dark outside and there's not supposed to be a D layer at night. Neat > how antenna's can be manufactured to do that. > > Just passed my tech and General on Sunday so I'll be on the bands as > soon as I find out my callsign and get an ionsphere for my antenna. I > destroyed the old one on the grinder and I hear you need a good > ionsphere to shoot good skip and hear far away stations. Reception has > been really shitty lately without the ionsphere. I looked through the > last 4 issues of QST and I couldn't find anyone selling ionsphere's. > Where can I get one, or do I have to buy a whole new antenna? > You don't need a new one. The old one probably got stuck in your coax by back-feed when you were grinding. Just get an RF brush and give your coax a few swipes and the ionosphere should pop right back out! Ed K7AAT Article: 224622 of rec.radio.amateur.antenna From: "Big Al" Subject: Wanted tube socketts & chimneys Message-ID: Date: Tue, 23 May 2006 01:51:51 GMT Wanted Looking for 2 socketts and chimneys for Eimac 4CX250 tubes. Email direct to ve7agw(at)shaw.ca (you know what to do with the (at). Thanks and 73...de ve7agw, Al Article: 224623 of rec.radio.amateur.antenna Message-ID: <44727448.8050103@fuse.net> Date: Mon, 22 May 2006 22:32:40 -0400 From: jawod Subject: Re: get help References: <1148340733.169536.23730@38g2000cwa.googlegroups.com> an_old_friend wrote: > Jay wrote: > >>I put the ball to a metal grinder and I could easily see an outer F layer >>and then the E layer. I couldn't find a D layer, but it was dark outside > > troll > Relax, it wasn't THAT bad of a joke. Not that GOOD, either. Article: 224624 of rec.radio.amateur.antenna From: "C64ER" References: <1mlcg.51373$Kn4.38159@bignews2.bellsouth.net> Subject: Re: Hamvention: Amateur Radio Manufacturers and Unfair Pricing... Message-ID: Date: Tue, 23 May 2006 03:16:35 GMT Here's a clue: Life is not fair. Never was, never will be. Deal with it. 73 Article: 224625 of rec.radio.amateur.antenna Date: Tue, 23 May 2006 13:17:21 +1000 From: Will Subject: Active HF antennas/DX engineering Message-ID: <44727ebe$1_1@news.iprimus.com.au> Anyone have experience in using something like a DX engineering active antenna? I want to set up a remote receiver. However i need something that would perform as well on receive as a Single 1/4 wave vertical on all bands. I thought about using a Steppir antenna, but something like the DX engineering active antenna seems more appealing. If anyone has homebrewed a active antenna pre-amp with good blocking, and intercept points i would like the info. I thought about using a couple of 2n5109's 2 stages, however impedance matching and buffer high impedance stage to match to a whip seems to be a black art. A homebrew solution would be more appealing. Will Article: 224626 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Variable coax length? References: Message-ID: <7kvcg.13806$fb2.2474@newssvr27.news.prodigy.net> Date: Tue, 23 May 2006 03:29:07 GMT Buck wrote: >>Did you take a look at the information on my web page at: >>http://www.qsl.net/w5dxp/notuner.htm > > Can you make that work using coax instead of open wire? You cannot use 50 ohm coax to transform the impedance to 50 ohms since 50 ohms is the center of the SWR circle. You could use side-by-side runs of 75 ohm coax to achieve a balanced Z0 of 150 ohms. But the reason that 450 ohm ladder-line works so well is that 450/50 = 9:1 and 4050/450 = 9:1. 450 ohm ladder-line can handle most any and all of the antenna impedances with an SWR less than 18:1 on the ladder-line. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224627 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Variable coax length? References: <7kvcg.13806$fb2.2474@newssvr27.news.prodigy.net> Message-ID: Date: Tue, 23 May 2006 03:33:59 GMT Cecil Moore wrote: > But the reason that 450 ohm ladder-line works so well is > that 450/50 = 9:1 and 4050/450 = 9:1. 450 ohm ladder-line > can handle most any and all of the antenna impedances with > an SWR less than 18:1 on the ladder-line. Forgot to say the above applies to dipoles that are 1/2 wavelength on the lowest frequency of operation. It doesn't apply to dipoles that are much shorter than 1/2 wavelength. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224628 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Variable coax length? Message-ID: <4a5572pgc995vqjm07j2qe5drdjv9bl6fq@4ax.com> References: <7kvcg.13806$fb2.2474@newssvr27.news.prodigy.net> Date: Tue, 23 May 2006 05:00:44 GMT On Tue, 23 May 2006 03:29:07 GMT, Cecil Moore wrote: >Buck wrote: >>>Did you take a look at the information on my web page at: >>>http://www.qsl.net/w5dxp/notuner.htm >> >> Can you make that work using coax instead of open wire? > >You cannot use 50 ohm coax to transform the impedance to >50 ohms since 50 ohms is the center of the SWR circle. > >You could use side-by-side runs of 75 ohm coax to achieve >a balanced Z0 of 150 ohms. > >But the reason that 450 ohm ladder-line works so well is >that 450/50 = 9:1 and 4050/450 = 9:1. 450 ohm ladder-line >can handle most any and all of the antenna impedances with >an SWR less than 18:1 on the ladder-line. Since Cecil's scheme operates the transmission line at very high VSWR on some frequencies (no matter what the line Zo), lossy lines such as typical coax may (probably will) have unacceptable losses on some frequencies. Owen -- Article: 224629 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT! FIGHT! FIGHT! Date: Mon, 22 May 2006 22:33:56 -0700 Message-ID: <12757m7m6v342f0@corp.supernews.com> References: <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <21360-446DFD85-1304@storefull-3257.bay.webtv.net> Richard Harrison wrote: > Richard Clark, KB7QHC wrote: > "Who. in your estimation, does qualify to discuss it?" > > If it`s about antennas, I nominate Kraus. If it`s about mathematics, > many marhematicians qualify. > > In algebra, y = mx + b, (the point slope formula), is called linear > because it is the graph of a straight line. > . . . But of course you realize that the function y = mx + b doesn't meet the requirements of a linear function when applied to network theory. Roy Lewallen, W7EL Article: 224630 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT! FIGHT! FIGHT! Date: Mon, 22 May 2006 22:55:42 -0700 Message-ID: <12758v1nbaq09f5@corp.supernews.com> References: <6571-446B5528-802@storefull-3251.bay.webtv.net> Richard Harrison wrote: > Cecil, W5DXP wrote: > "Assuming the source signal is a pure sine wave, if the standing wave > current "isn`t in general sinusoidally shaped (as Roy said)", then the > antenna would have to be introducing harmonic radiation that doesn`t > exist in the source signal." > . . . Either Cecil is misquoting me, or Richard is misquoting Cecil. Cecil calls the total current the "standing wave current". I never said that the standing wave current isn't sinusoidally shaped. I said that the *envelope* of the standing wave -- that is, a graph of the magnitude of the current on a transmission line as a function of position along the line -- is not sinusoidally shaped except in the special case of a complete reflection. This isn't a personal theory, but a very well established fact which can easily be derived from fundamental equations. (Or it can even be found clearly stated in texts for those unable to understand the derivation.) On antennas, the current distribution (magnitude of current vs position) is generally not sinusoidal either, although it's approximately so on thin wire antennas. Assuming that the transmission line is driven with a pure sine wave, the forward, reverse, and total currents as a function of *time* will be sinusoidal and consequently no harmonics will be generated. (I'm of course neglecting nonlinear effects which might occur in a real transmission line or antenna such as magnetic conductors or nonlinear dielectrics. But in practical terms these will be virtually unmeasurable with ordinary coax or twinlead and amateur power levels.) It's hard to determine whether Cecil's sustained confusion between a time waveform and a graph of amplitude vs distance is intentional or if the concepts are really mixed up for him. It has, in either case, provided a convenient diversion from his basic strange theories at the time it was getting particularly hard for him to continue supporting them. Roy Lewallen, W7EL Article: 224631 of rec.radio.amateur.antenna Date: Tue, 23 May 2006 00:44:25 -0600 From: BKR Subject: Re: sgc dipole? References: Message-ID: <4472af4e@nntp.zianet.com> ml wrote: > hi > > I was wondering a few things i read about in my sgc tuner manual about > dipoles > > > a) they say or sorta recomend that if your making a simple horiz ctr fed > dipole, it's 'best' to have one leg longer > > why is that 'a good idea' what happens that makes this sorta advisable > > > b) they recomend the longer leg to be the rf 'ground'' side , really > confused as to why, my gut would tell me to make the hot side the > longest leg so i am confused > > > > can anyone help me understand the above, i kinda understand how the wave > looks on a regular horizontal ctr fed dipole is > > > any help appreciated It is the same reason that when you build a standard 2 meter ground plane antenna, that the ground plane is constructed with wires or rods about 20.5 inches each. That is close to a quarter wave without compensating for end effect. The radiating element is about 19.5 inches which does take the end effect into account. It will result in less RF on the outside of the coax. Article: 224632 of rec.radio.amateur.antenna From: "Jerry Martes" Subject: Question about the uses for an antenna design Message-ID: <6hAcg.5443$oa3.1513@trnddc08> Date: Tue, 23 May 2006 09:07:14 GMT I have determined a way to feed four dipoles to provide good horizon to horizon coverage at all angles for circularly polarized signals. It works quite well for Low Earth Orbiting satellites. I lack the skills needed to analyze the concept. I would like to make this concept available to anyone who wants to build their own antenna. I have a working model that seems to have no serious minimums when receiving NOAA satellites at 137 MHz. The concept is quite simple and probably easily understood by any antenna engineer. Does anyone know where I might locate someone who would have interest in knowing about this antenna concept that I have chosen to call the Cross concept. Jerry KD6JDJ Article: 224633 of rec.radio.amateur.antenna From: "Kevin & Natalia" Subject: Control Unit for Home Built Rotator from Pitch-Prop Motor Date: Tue, 23 May 2006 21:52:19 +1200 Message-ID: <1148377755.519950@ftpsrv1> Hi All, I acquired a Pitch-Prop motor a number of years ago, with the intention of building a antenna rotator. I still have the intention of doing this, and have checked the motor for operation. This works out very nice, and was able to control it to different speeds with different voltage. I have a construction design for the mounting of the motor and gearbox to the tower, and antenna. The problem I have now, is I wish to construct a suitable control unit, with digital readout, and the possibility of controlling via a mini PIC control, or via PC. I have searched the internet without much success, so my next course of action was to see if anyone on these groups might be of help. So I put my hands up for HELP! :) Any help would be gratefully received. Thanks in Advance. Kevin, ZL1KFM. Article: 224634 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <0bpr62pdua5b09mn0cpm1vjsds6fvkinih@4ax.com> <21360-446DFD85-1304@storefull-3257.bay.webtv.net> <12757m7m6v342f0@corp.supernews.com> Message-ID: Date: Tue, 23 May 2006 12:14:32 GMT Roy Lewallen wrote: > Richard Harrison wrote: >> In algebra, y = mx + b, (the point slope formula), is called linear >> because it is the graph of a straight line. > > But of course you realize that the function y = mx + b doesn't meet the > requirements of a linear function when applied to network theory. I knew what Richard meant. Quoting "Linear Network Theory", by Ferris: "In the functional relationship, h(t)=kf(t), no matter what h(t) and f(t) represent, the relation h(t)=kf(t) must be linear. ... An elementary concept, then, is that h(t) and f(t) are related by a straight line of the form h(t) = mt + b." -- 73, Cecil http://www.qsl.net/w5dxp Article: 224635 of rec.radio.amateur.antenna From: "Jeff Dieterle" Subject: Special Tower Bolts Date: Tue, 23 May 2006 08:41:46 -0500 Message-ID: <84062$447302fc$ce6b49db$18022@COMTECK.COM> Where do I find the galvanized bolts with the spline under the head to assemble a 3-leg tower?? Article: 224636 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <6571-446B5528-802@storefull-3251.bay.webtv.net> <12758v1nbaq09f5@corp.supernews.com> Message-ID: <3BDcg.29574$Lm5.3231@newssvr12.news.prodigy.com> Date: Tue, 23 May 2006 12:53:19 GMT Roy Lewallen wrote: > Richard Harrison wrote: > >> Cecil, W5DXP wrote: >> "Assuming the source signal is a pure sine wave, if the standing wave >> current "isn`t in general sinusoidally shaped (as Roy said)", then the >> antenna would have to be introducing harmonic radiation that doesn`t >> exist in the source signal." > > Either Cecil is misquoting me, or Richard is misquoting Cecil. Richard quoted me correctly. I did *NOT* quote you. I merely stated what I thought you said. > Cecil calls the total current the "standing wave current". That is absolutely false. Total current equals standing wave current plus traveling wave current. Or standing wave current equals total current minus traveling wave current. Subtract out the traveling wave component and a pure standing wave component is left. Note that you did not quote me. You merely stated what you thought I said and you were mistaken. > I never said > that the standing wave current isn't sinusoidally shaped. I said that > the *envelope* of the standing wave -- that is, a graph of the magnitude > of the current on a transmission line as a function of position along > the line -- is not sinusoidally shaped except in the special case of a > complete reflection. The envelope of the standing wave current is the same whether reflection is complete or not since the traveling wave current has been subtracted from the total current. Seems you should have said the total current envelope is not sinusoidal. The standing wave current envelope is obviously sinusoidal since the traveling wave has been subtracted. > This isn't a personal theory, but a very well > established fact which can easily be derived from fundamental equations. Please provide a reference that says after the traveling wave current has been subtracted from the total current, the resulting standing wave current envelope is not sinusoidal. > (Or it can even be found clearly stated in texts for those unable to > understand the derivation.) On antennas, the current distribution > (magnitude of current vs position) is generally not sinusoidal either, > although it's approximately so on thin wire antennas. Just because the scale of the position axis changes with VF doesn't mean things become non-sinusoidal. > Assuming that the transmission line is driven with a pure sine wave, the > forward, reverse, and total currents as a function of *time* will be > sinusoidal and consequently no harmonics will be generated. This statement contradicts what I thought you said before. Seems we are now in agreement. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224637 of rec.radio.amateur.antenna From: W8LNA Subject: Re: Special Tower Bolts References: <84062$447302fc$ce6b49db$18022@COMTECK.COM> Message-ID: Date: Tue, 23 May 2006 13:39:26 GMT Jeff Dieterle wrote: > Where do I find the galvanized bolts with the spline under the head to > assemble a 3-leg tower?? > > I go to http://www.fastenal.com/ for real hardware but I don't know if they have exactly what you desire. W8LNA Article: 224638 of rec.radio.amateur.antenna Date: Tue, 23 May 2006 23:44:50 +1000 From: Will Subject: Yacht Rf ground and radials Message-ID: <447311d0_1@news.iprimus.com.au> I want to set up a hf antenna for my sailboat. I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Will Article: 224639 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 08:55:42 -0500 Message-ID: <24025-4473145E-1862@storefull-3258.bay.webtv.net> References: <12757m7m6v342f0@corp.supernews.com> Roy Lewallen, W7EL wrote: "But of course you realize that the function y = mx + b doesn`t meet the requirements of a linear function when applied to network theory." Works for me. Linear means the graph of the function is a straight line. f(x) = y = mx + b is called linear because its graph is a straight line. A straight line is the shortest distance between two points. In y = mx + b, m is a constant determining the slope of the line. x is is the independent variable. b is the offset or point along the x-axis where the line crosses. y then is a linear function of x because its slope is always mx, but displaced in the x-direction by a constant value, namely b. y is linear the same as IR is linear, or by substitution, E is linear in Ohm`s law where E=IR. For any value of I, voltage = IR and the graph of I versus E is a straight line with a slope equal to R. Resistance is a common factor in network theory. Best regards, Richard Harrison, KB5WZI Article: 224640 of rec.radio.amateur.antenna From: Buck Subject: Re: Multiband doublet feedline length Message-ID: References: Date: Tue, 23 May 2006 10:08:59 -0400 >I just tacked on additional ladder line for a total of 91 feet, it's >draped all over the place. The matchbox tunes more difficult on 75 M >but tuned right up on 40. The matchbox controls are skewed quite a ways >off the center point. tuning control is at 26 and match is about 15 so >it does not seem to like this length any better. I could tack on >another 15 feet but then I'd have to lay it on the ground which is not >good. I could shorten up the original 67 feet to perhaps 50 plus but >that would make it worse? Suppose you trim the feedline a few inches at the time until the tuner works on 80 and the other bands as well? -- 73 for now Buck N4PGW Article: 224641 of rec.radio.amateur.antenna Date: Tue, 23 May 2006 16:10:22 +0200 From: ADMIN Subject: Earn up to 1000 $ per month only for reading your Mails!!!!!!!! Message-ID: <4473161d$0$59880$afc38c87@news6.united-newsserver.de>

 

Article: 224642 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 09:33:44 -0500 Message-ID: <6571-44731D48-1639@storefull-3251.bay.webtv.net> References: <12758v1nbaq09f5@corp.supernews.com> Roy Lewallen, W7EL wrote: "Either Cecil is misquoting me, or Richard is misquoting Cecil." I apologize if I misquoted anyone. It was unintentional, On page 239 of Kraus` 1950 edition of "Antennas" he wrote: "It is generally assumed that the current distribution of an infinitesimally thin antenna (l/a=infinity) is sinusoidal, and that the phase is constant over a 1/2-wavelength interval, changing abruptly by 180-degrees between intervals." Cosine has the same shape as sine. They are identical except for a 90-degree phase displacement. Sine starts at zero. Cosine starts at one. Sinusoidal covers both sine and cosine shapes. Best regards, Richard Harrison, KB5WZI Article: 224643 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: Yacht Rf ground and radials Date: Tue, 23 May 2006 09:48:05 -0500 Message-ID: <127685875615t64@corp.supernews.com> References: <447311d0_1@news.iprimus.com.au> I don't think Icom would jack you around about this, do you really? Marine radios are a large part of their business and they do know their business. Uhmmm...this isn't one of those ionosphere posts is it? Butch Will wrote: > I want to set up a hf antenna for my sailboat. > > I have read various guides from Icom etc. > > They suggest running copper foil to a Dynaplate and use sea water as > the ground. How can this work when the Dynaplate is below sea water? > > Is sea water equal to copper wire radials as a RF ground system? > > Does sea water make a good enough ground without radials? > > How can a piece of copper metal about 1 ft square equal several > radials laying on the boats deck? > > Why do i have to use copper foil when most other people suggest using > ordinary copper wire? > > Over seawater what would be the best number of radials to use > considering that maximum length i can run is 40 ft. I am planning to use > a backstay antenna with a SGC 230 Tuner. > > All ideas and comments appreciated. > > Will Article: 224644 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: FIGHT! FIGHT! FIGHT! References: <6571-446B5528-802@storefull-3251.bay.webtv.net> <12758v1nbaq09f5@corp.supernews.com> <3BDcg.29574$Lm5.3231@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 23 May 2006 15:05:52 GMT Cecil Moore wrote: > Roy Lewallen wrote: > >> Richard Harrison wrote: >> >>> Cecil, W5DXP wrote: >>> "Assuming the source signal is a pure sine wave, if the standing wave >>> current "isn`t in general sinusoidally shaped (as Roy said)", then the >>> antenna would have to be introducing harmonic radiation that doesn`t >>> exist in the source signal." >> >> >> Either Cecil is misquoting me, or Richard is misquoting Cecil. > > > Richard quoted me correctly. I did *NOT* quote you. I merely > stated what I thought you said. > >> Cecil calls the total current the "standing wave current". > > > That is absolutely false. Total current equals standing wave > current plus traveling wave current. Or standing wave current > equals total current minus traveling wave current. Subtract > out the traveling wave component and a pure standing wave > component is left. I thought I was following this somewhat, but now it appears that I am not. I thought there were two traveling waves, forward and reverse, with the reverse wave being a reflection of the forward wave from the end of the antenna. I thought that the total current was the sum of the two waves, could be measured with an ammeter, and that it could be referred to as the standing wave. Are you now saying that the standing wave and the reverse wave are the same wave? Confusedly, John Article: 224645 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Question about the uses for an antenna design References: <6hAcg.5443$oa3.1513@trnddc08> Message-ID: Date: Tue, 23 May 2006 15:05:02 GMT Jerry Martes wrote: > I have determined a way to feed four dipoles to provide good horizon to > horizon coverage at all angles for circularly polarized signals. Hi Jerry, how is your antenna superior to a two-dipole turnstile? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224646 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <6571-446B5528-802@storefull-3251.bay.webtv.net> <12758v1nbaq09f5@corp.supernews.com> <3BDcg.29574$Lm5.3231@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 23 May 2006 15:48:07 GMT John - KD5YI wrote: > I thought there were two traveling waves, forward and reverse, with the > reverse wave being a reflection of the forward wave from the end of the > antenna. I thought that the total current was the sum of the two waves, > could be measured with an ammeter, and that it could be referred to as > the standing wave. If the antenna were lossless, that would be true. However, the antenna loses RF energy to radiation, ground, I^2*R, etc. Since the same thing is true of a transmission line, let's first look at a transmission line. Let's say we measure (at the tuner) a forward power of 100 watts and a reflected power of 80 watts. We can assume that the losses in the line and the power delivered to the load add up to 20 watts. The 20 watts can be associated with a pure forward traveling wave. The other 80 watts of the forward power and the 80 watts of reflected power can be associated with a pure standing wave. The equations for such would look something like this. Itot = Ifor*cos(kx+wt) + Iref*cos(kx-wt) = Itot = I1*cos(kx+wt) + I2*cos(kx)*cos(wt) I1 would be considered to be the part of the traveling wave that is delivering net power to the load. I2 would be considered to be the standing wave current delivering no net power to the load. It's just another way of mathematically partitioning the currents. Let's assume for the sake of discussion that the forward wave at the antenna feedpoint is 100 watts and the reflected wave at the antenna feedpoint is 80 watts. That means there are 20 watts of total losses. We can partition the currents in the same way that we did in the transmission line. Incidentally, if we assume the antenna is 1/2 wavelength with a Z0 of 600 ohms, we can calculate the feedpoint impedance just as if it were a piece of transmission line with a resistive termination. Anybody want to try that exercise? What impedance is seen looking into a 600 ohm 1/4WL open stub when the forward power is 100 watts and the reflected power is 80 watts? > Are you now saying that the standing wave and the reverse wave are the > same wave? The reverse wave is half of the standing wave. The other half of the standing wave is part of the forward wave. One might say that the energy in the reverse wave neutralizes the ability of the forward wave to deliver that same amount of energy to the load. And indeed, we know the power delivered to the load is the forward power minus the reflected power. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224647 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Yacht RF ground and radials Date: Tue, 23 May 2006 10:48:47 -0500 Message-ID: <24587-44732EDF-17@storefull-3256.bay.webtv.net> References: <447311d0_1@news.iprimus.com.au> Will wrote: "Does sea water make a good enough ground without radials?" It`s the best you can get in a boat at sea, The point is to get a good connection to the sea. You don`t need radials for that. That`s why a thin copper plate is recommended. Copper is durable and poisonous to sea organisns which may foul the surfaces of other materials. Skin effect applies. Bolting to a spot inside a metal hull means the RF must travel from the bolt location inside the hull (it can`t penetrate the hull) to an edge where it reaches from the inside surface to the outside surface and thence to the waterline. DC resistsance of a conductor is resistivity x length divided by crossection. AC resistance is more but proportioned to the DC resistance. A large crossection or area produces a low resistance. That`s why the plate is better for contacting the water than a wire. Its also why the seawater has a low resistance despite a higher resistivity than copper. The huge crossection of seawater has very low resistance in most cases and its reactance is low too. Low resistance and low reactance make a good path for RF. Best regards, Richard Harrison, KB5WZI Article: 224648 of rec.radio.amateur.antenna From: "dale.j. " Subject: Re: Multiband doublet feedline length References: Message-ID: Date: Tue, 23 May 2006 15:55:44 GMT In article , Buck wrote: > >I just tacked on additional ladder line for a total of 91 feet, it's > >draped all over the place. The matchbox tunes more difficult on 75 M > >but tuned right up on 40. The matchbox controls are skewed quite a ways > >off the center point. tuning control is at 26 and match is about 15 so > >it does not seem to like this length any better. I could tack on > >another 15 feet but then I'd have to lay it on the ground which is not > >good. I could shorten up the original 67 feet to perhaps 50 plus but > >that would make it worse? > > Suppose you trim the feedline a few inches at the time until the tuner > works on 80 and the other bands as well? It's actually working pretty good right now and I have the ladder line all symmetrical in the way it's routed from the antenna. I'm using my original 126 ft long horizontal wire fed in the middle with 450 ohm ladder which is 67 feet long going to my Johnson KW matchbox. It tunes it on 75 and 40. 40 is a little tricky but I can get there ok. I also use this same antenna as an inverted L on 160 by re-routing the ladder via a knife switch to my Drake MN-2700 tuner. It tunes very nice on 160. When I get time from painting the house and other chores I will try to sit down and learn EZnec, then tweak the feedline and maybe the antenna too. I wish I had more room, I love to experiment with wire type antennas. 73 Dale, K9VUJ -- Email: dalej2@mac.com Article: 224649 of rec.radio.amateur.antenna From: Robert Kubichek Subject: Re: Control Unit for Home Built Rotator from Pitch-Prop Motor Date: Tue, 23 May 2006 11:12:02 -0500 Message-ID: <4dgqilF1987e2U1@individual.net> References: <1148377755.519950@ftpsrv1> Kevin & Natalia wrote: > Hi All, > > I acquired a Pitch-Prop motor a number of years ago, with the intention of > building a antenna rotator. > I still have the intention of doing this, and have checked the motor for > operation. This works out very nice, and was able to control it to different > speeds with different voltage. > I have a construction design for the mounting of the motor and gearbox to > the tower, and antenna. > > The problem I have now, is I wish to construct a suitable control unit, with > digital readout, and the possibility of controlling via a mini PIC control, > or via PC. > > I have searched the internet without much success, so my next course of > action was to see if anyone on these groups might be of help. > So I put my hands up for HELP! :) > > Any help would be gratefully received. > > Thanks in Advance. > > Kevin, ZL1KFM. > > It is entirely doable, check here "http://forums.parallax.com/forums/default.aspx" for ideas on how to implement your project using a Basic Stamp... I would do it with digital position sensing, with an lcd display showing direction of antenna.. Bob N9LVU Article: 224650 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 09:41:27 -0700 Message-ID: <1276ept16to7h81@corp.supernews.com> References: <6571-446B5528-802@storefull-3251.bay.webtv.net> <12758v1nbaq09f5@corp.supernews.com> <3BDcg.29574$Lm5.3231@newssvr12.news.prodigy.com> > Cecil Moore wrote: >> Roy Lewallen wrote: >> . . . >> Richard quoted me correctly. I did *NOT* quote you. I merely >> stated what I thought you said. >> >>> Cecil calls the total current the "standing wave current". >> >> >> That is absolutely false. Total current equals standing wave >> current plus traveling wave current. Or standing wave current >> equals total current minus traveling wave current. Subtract >> out the traveling wave component and a pure standing wave >> component is left. I could have sworn Cecil had used it in that sense before. But Ok, I'll go along with the new definition. Any basic analysis of transmission line operation shows that the total current is simply the sum of the traveling wave currents. Consequently the "standing wave current" as defined by Cecil is zero. So by "standing wave current", Cecil means zero. This is getting stranger by the day. Roy Lewallen, W7EL Article: 224651 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 09:52:50 -0700 Message-ID: <1276ff6itsva2ca@corp.supernews.com> References: <12757m7m6v342f0@corp.supernews.com> <24025-4473145E-1862@storefull-3258.bay.webtv.net> I'm sure that somewhere in one of your texts you can find the definition of linear as applied to networks. Once you do, though, a little thought is required to discover that y = mx + b doesn't satisfy the criteria for network linearity. To be linear, a network has to satisfy superposition. This means that: If y1 is the response to excitation x1 and y2 is the response to excitation x2, then the response to x1 + x2 must be y1 + y2. Let's try that with your function. The response to x1 is: y(x1) = mx1 + b The response to x2 is: y(x2) = mx2 + b The sum of y(x1) and y(x2) is: y(x1) + y(x2) = m(x1 + x2) + 2b But response to x1 + x2 is: y(x1 + x2) = m(x1 + x2) + b These are not equal as they must be to satisfy superposition and therefore the requirements for linearity. Roy Lewallen, W7EL Richard Harrison wrote: > Roy Lewallen, W7EL wrote: > "But of course you realize that the function y = mx + b doesn`t meet the > requirements of a linear function when applied to network theory." > > Works for me. > > Linear means the graph of the function is a straight line. > > f(x) = y = mx + b is called linear because its graph is a straight line. > > A straight line is the shortest distance between two points. > > In y = mx + b, m is a constant determining the slope of the line. x is > is the independent variable. b is the offset or point along the x-axis > where the line crosses. > > y then is a linear function of x because its slope is always mx, but > displaced in the x-direction by a constant value, namely b. > > y is linear the same as IR is linear, or by substitution, E is linear in > Ohm`s law where E=IR. For any value of I, voltage = IR and the graph of > I versus E is a straight line with a slope equal to R. > > Resistance is a common factor in network theory. > > Best regards, Richard Harrison, KB5WZI > Article: 224652 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Tue, 23 May 2006 10:00:38 -0700 Message-ID: <1276ftr2cm9h294@corp.supernews.com> References: <1148301147.519366.35860@j73g2000cwa.googlegroups.com> <23154-4471D317-1504@storefull-3254.bay.webtv.net> Richard Harrison wrote: > Gene Fuller wrote: > "Terman certainly did not deny the existence of skin effect that keeps > fields out of the interior of conductors.' > > true. The point is, shielding from magnetic fields is different from > electric fields. On page 35 of his 1955 edition, Terman writes: > "Magnetic flux in attempting to pass through a shield (copper or > aluminum) induces voltage in the shield which gives rise to eddy > currents. These eddy currents oppose the action of the flux, and in > large measure prevent its penetration through the shield." > . . . Am I mistaken, but is this not a clear statement that a copper or aluminum shield will block magnetic flux, along with an explanation of why it happens? Roy Lewallen, W7EL Article: 224653 of rec.radio.amateur.antenna From: Me Subject: Re: Yacht Rf ground and radials References: <447311d0_1@news.iprimus.com.au> <127685875615t64@corp.supernews.com> Message-ID: Date: Tue, 23 May 2006 17:49:25 GMT In article <127685875615t64@corp.supernews.com>, Butch Magee wrote: > I don't think Icom would jack you around about this, do you really? > Marine radios are a large part of their business and they do know their > business. Uhmmm...this isn't one of those ionosphere posts is it? > > Butch > > > > > Will wrote: > > I want to set up a hf antenna for my sailboat. > > > > I have read various guides from Icom etc. > > > > They suggest running copper foil to a Dynaplate and use sea water as > > the ground. How can this work when the Dynaplate is below sea water? > > > > Is sea water equal to copper wire radials as a RF ground system? > > > > Does sea water make a good enough ground without radials? > > > > How can a piece of copper metal about 1 ft square equal several > > radials laying on the boats deck? > > > > Why do i have to use copper foil when most other people suggest using > > ordinary copper wire? > > > > Over seawater what would be the best number of radials to use > > considering that maximum length i can run is 40 ft. I am planning to use > > a backstay antenna with a SGC 230 Tuner. > > > > All ideas and comments appreciated. > > > > Will No, Not an Ionsphere Post, just a guy who has no clue about the technology that he wants to use, and he is asking questions, trying to learn. From the replys he has received so far, he is finding out that 99% of the hams, don't have a clue about MF/HF Marine Radio Antenna systems Design, either. I suggest that he head on over to rec.boat.electronics, and ask Larry, Gary S., Old Chief Lynn, or one of the other Old Salts, that have been doing these installations for decades, and have the experience in the technology being asked about. Most hams think that MF/HF Marine Radio Antenna Systems design should follow the same rules that Land Startions use. Well that isn't the case, and usually ends up is a "Piss Poor", marginal system that only talks "when the Band is open", and "when the Band is open" even a wet noodle will radiate enough to communicate. Me Article: 224654 of rec.radio.amateur.antenna From: chuck Subject: Re: Yacht Rf ground and radials References: <447311d0_1@news.iprimus.com.au> <23c672tptm5qalf9vhnm3tn1mtotf509hs@4ax.com> Message-ID: Date: Tue, 23 May 2006 18:35:16 GMT Richard Clark wrote: > On Tue, 23 May 2006 23:44:50 +1000, Will > wrote: >> They suggest running copper foil to a Dynaplate and use sea water as >> the ground. How can this work when the Dynaplate is below sea water? > > Hi Will, > > Below is better than above, to say the least. How much below is > immaterial. > >> Is sea water equal to copper wire radials as a RF ground system? > > Skip the pursuit of the Holy Grail in radials, this may lead you to > start carrying buckets of dirt which screws up buoyancy. > >> Why do i have to use copper foil when most other people suggest using >> ordinary copper wire? > > Probably more surface area. > >> All ideas and comments appreciated. > > How good (or poor) sea water is for matching and loss, is seeing the > glass 3/4's empty. How good sea water is for propagation is seeing > the pitcher nearby and filling your glass several times. > > 73's > Richard Clark, KB7QHC A few additional questions along these lines for the group (with some paraphrasing): 1. What is the skin depth in salt water at 14 MHz? How would this affect a ground plate at four feet below the surface? 2. What would the ohmic losses be over a one square foot by 33 foot path through salt water? 3. How well would the ground plate work on fresh water bodies, such as much of the Chesapeake, the Great Lakes, and various rivers and tributaries often used by cruisers? How would it compare with radials over fresh water? 4. Can anyone cite a published and reproducible study in which the RF losses through salt water were measured and compared with losses through one or more copper wire "radials" on or below deck of a typical cruising vessel? Or is there a published theoretical analysis of this comparison? Looking for more than the casual, anecdotal stuff. 5. Will a four foot length of wire dropped into saltwater provide a "good" RF "ground" and on what is the answer based? I need enlightenment! Thanks, and 73, Chuck NT3G Article: 224655 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Hamvention: Amateur Radio Manufacturers and Unfair Pricing... Message-ID: References: <1mlcg.51373$Kn4.38159@bignews2.bellsouth.net> <8Dlcg.5361$x4.2824@newsread3.news.pas.earthlink.net> <447316C8.1080203@w2agn.net> Date: Tue, 23 May 2006 18:41:07 GMT On Tue, 23 May 2006 10:06:00 -0400, "John L. Sielke" wrote: >Billy Smith wrote: >> laborkei wrote: >> >>> Amateur Radio Manufacturers and unfair pricing! >>> >>> Here I sit the day after Dayton, calling around to all the dealers >>> looking >>> for a HF Transceiver. There were some fantastic prices offered on >>> equipment >>> (As much as $500 off list), and the dealers are back to charging full >>> price >>> today. >>> >>> I am told by the dealers I called, that the Manufacturers were making >>> deals >>> with them so they could sell there inventories much cheaper, and the >>> orders >>> had to be taken at Dayton. Today, the day after when most of these orders >>> had not even shipped yet, they are back up to full retail price. >>> >>> To be fair, Manufacturers should allow these prices for a time period >>> after >>> Dayton to give other Amateurs who could not drive to Dayton an >>> opportunity >>> to get the same deals. >>> >>> I think we should all write to them and let them know how we feel. >>> This is >>> unfair ! >>> >>> >> >> Cry us a river. They made the offers at Dayton and that was what they as >> private businesses chose to do. You could have either went to Dayton or >> found whatever way to get a radio from there. Get over it. >> >Maybe you can get some left wing liberal whiners to feel sorry for you, but not >likely. Ahem, being a liberal left winger, why do you think folks of my ilk would feel sorry for the gentleman? A sale is a sale, and sales are always are for a limited time only. Politics has nada to do wit'it... bob k5qwg > This is a free market, remember? Or would you prefer the government >telling businesses what they can charge. > >UNBELIEVABLE that some people expect soemthing for nothing all the time. Article: 224656 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <6571-446B5528-802@storefull-3251.bay.webtv.net> <12758v1nbaq09f5@corp.supernews.com> <3BDcg.29574$Lm5.3231@newssvr12.news.prodigy.com> <1276ept16to7h81@corp.supernews.com> Message-ID: Date: Tue, 23 May 2006 18:52:19 GMT Roy Lewallen wrote: > Any basic analysis of transmission > line operation shows that the total current is simply the sum of the > traveling wave currents. Consequently the "standing wave current" as > defined by Cecil is zero. So by "standing wave current", Cecil means zero. Your last two statements are false. Please stop trying to tell others what I mean when it is obvious that you don't know what I mean. > This is getting stranger by the day. Why can't you and I just have a reasonable technical discussion? Sooner or later, the readers who care at all about the truth are going to see through your attempts to falsify what I have said. Since you obviously have not understood what I said in the past I guess I need to simplify it for you so here goes: Let A be the forward traveling current. Let B be the rearward traveling current. Let C be the part of the forward traveling current that flows through the load. Let D be the part of the forward traveling current that doesn't flow through the load and becomes B after being reflected. A = C + D The total forward current is divided into two components, one accepted by the load and one rejected by the load. The following is phasor addition Total Current = A + B = (C + D) + B = C + (D + B) (D + B) is the pure standing wave current component, a part of the forward current equal to the reflected current. The total current is indeed the phasor sum of the forward and reflected current. The total current is also the sum of the load current plus the pure standing wave current. The pure standing wave current envelope is sinusoidal. -- 73, Cecil http://www.qsl.net/w5dxp The day a Guru starts believing that He already knows everything is the day He becomes hopelessly ignorant. Article: 224657 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: sgc dipole? Date: Tue, 23 May 2006 19:01:55 -0000 Message-ID: <1276n13d85ld919@corp.supernews.com> References: <1148390757.341256.120320@i40g2000cwc.googlegroups.com> In article <1148390757.341256.120320@i40g2000cwc.googlegroups.com>, wrote: >Maybe you should ask them why they want customers to do that. It sounds >like witchcraft to me. Well, I'd probably call it "lore", as in "Everybody says that it seems to work better that way." I don't think it has anything to do with the actual RF radiation behavior of the dipole antenna, once a match is achieved... it shouldn't matter for this purpose which side of the dipole is longer. I think it has everything to do with the tuner's ability to find a match. As I understand it (and this is all second- and third-hand knowledge): the SGC tuners (like the SEA tuners from which they're said to have been copied and like a lot of similar tuners from Motorola and others) were designed primarily to match short verticals (whips and wires) working against a much larger ground system. They're designed for unbalanced applicatios. Their original application was marine and vehicle use, with the tuner very robustly "bonded" to the metal chassis of the vehicle. The manuals still make it clear that a large, well-bonded ground/counterpoise system connected directly to the tuner chassis is what these tuners really "want to see". The acceptable-SWR range for a dipole to be matched is rather limited... IIRC the SGC-230 manual says that it's limited to 5:1 or so. When used to center-feed a dipole, making the ground-side leg longer than the hot-side leg increases the capacitance to ground on that side and may tend to mimic the environment for which the tuners were really designed. As to _why_ they want to see it - my guess is that it has to do with the details of the tuner's internal circuitry (it's an L or PI tuner), the tuning-setting search algorithm in the microprocessor, and perhaps the electrical details of the SWR-and-impedance measuring/bridge circuit. The manual comments that if the counterpoise system isn't significantly bigger than the radiator, the tuner's microcontroller may "become confused" and try to feed power to the ground system rather than to the radiator. Yes, I know, this doesn't really makes sense electrically... I suspect that it really means that the matching-component search algorithm starts making decisions which actually drive the system further away from a good match rather than towards it. It's also possible that such installations are more prone to high levels of RF current flow on the feedline from the transmitter, and also to high common-mode RF flow on the power and control lines, and that this RF might tend to confuse the tuner's SWR-and-impedance sensors and thus disrupt the match-search process. My own experiences with an SGC tuner seem to confirm the limitations and warnings that SGC publishes about the hookup required to establish a match. A couple of years ago I picked up a first-generation SGC 230 (apparently never used, as it was still in the original shipping box and bag) at a hamfest for all of $30. I've tried it, and I _can_ get it to work, but in my installation it's finicky in the extreme about its ability to match a wire. I've never had any success in getting it to match a dipole. It doesn't do well at all when trying to match a longwire (even one of what the manual says is an optimal length) when mounted on my house wall... I suspect that the 8' of wire between the tuner case, and the point at which I've bonded my counterpoise/radial/ground system, has too much inductance. It also seems to be sensitive to which radio it's used with. It "likes" my old Ten-Tec Scout better than my new Kenwood TS-2000 - it'll achieve a match for the former that it won't achieve for the latter. I suspect that the problem is that the TS-2000's transmitter has SWR-sensitive power foldback - the TS-2000 keeps changing its transmit power as the SGC switches between different match-component settings, and I believe that this is completely confusing the SGC's search logic. Using the same tuner and antenna, on the same frequency, with the Ten-Tec (which doesn't use an SWR-sensing power reduction circuit), a match can often be achieved in a few seconds. I've given up trying to use it for my home station, as I haven't been able to put together a reliable installation with it. I'll keep it around for field use - grounded to a vehicle or a big chain-link fence or something like that, it may work well enough. My conclusion is that these L/Pi long-wire tuners are really best suited for the uses for which they were designed... matching a whip or wire, fed against a Big Yellow Taxi or some other large mass of sheetmetal or a really good radial system. For feeding a balanced antenna, I think you may have better results with a tuner which is explicitly designed for that sort of job. Possibly SGC has improved the matching/searching behavior of their tuners/couplers when used in balanced-antenna applications, in the newer versions. The one I have is at least ten years old, I think - so old that it's in a non-weatherproof aluminum chassis rather than a weatherproof plastic one, and it doesn't have the "tune lock" feature of the newer ones. Dunno for sure. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 224658 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <12757m7m6v342f0@corp.supernews.com> <24025-4473145E-1862@storefull-3258.bay.webtv.net> <1276ff6itsva2ca@corp.supernews.com> Message-ID: Date: Tue, 23 May 2006 19:11:20 GMT Roy Lewallen wrote: > I'm sure that somewhere in one of your texts you can find the definition > of linear as applied to networks. Once you do, though, a little thought > is required to discover that y = mx + b doesn't satisfy the criteria for > network linearity. You have missed the point, Roy. It is the relationship between functions that has to be linear. If f(x) is the input and y is the output where y = h(x) = k*f(x), a plot of the output Vs input will yield a straight line of the form mx + b. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224659 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT? Here is another W8JI myth bone! References: <1148301147.519366.35860@j73g2000cwa.googlegroups.com> <23154-4471D317-1504@storefull-3254.bay.webtv.net> <1276ftr2cm9h294@corp.supernews.com> <1148404690.891299.235780@38g2000cwa.googlegroups.com> Message-ID: Date: Tue, 23 May 2006 19:22:13 GMT w8ji@akorn.net wrote: > If a person is confused by or somehow DOESN'T understand what Terman is > saying, he or she might take it to mean magnetic fields can travel > unimpeded through a shield. I have asked this simple question a number of times and, so far, no one has answered. It should have a simple answer so here it is again. Does a 60 Hz magnetic field travel virtually unimpeded through a coax shield? This question involves 60 Hz noise being coupled through coax. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224660 of rec.radio.amateur.antenna From: gene@csl.uiuc.edu (Gene Gardner) Subject: Built Mobile using Lewallen "fat dipole" concept Date: Tue, 23 May 2006 20:33:16 +0000 (UTC) Message-ID: I built a Hi-performance 75 meter Mobile antenna based on Roy Lewallen's explanation of how a car body should ideally be used as the "fat" lower portion of a vertical dipole. Ideally, the mast should be placed at the top center of the car for good symmetry, but this is usually impractical for 75 meters in motion with a 13 ft height limit. But on my 96 Dodge Ram truck, this idea was more practical. The truck box (mine was short bed) is separated from the cab in the upper area above the frame. To utilize the truck box as a "fat" vertical lower portion of a vertical dipole, I mounted an aluminum rail between the top edge of the box sides, so that the center of the alumimum rail becomes the highest electrical center of the box. The mast is mounted here (insulated) and becomes the feed point for the coax. But to prevent the "grounded" feed coax from compromising the "elevated" feed point, I coiled several turns of the feed coax (RG-58) thru a few large ferrite cores from my junk box. Presumeably, this minimizes any horizontal currents on the coax shield and thus minimizes ground losses. As Roy points out, horizontal currents near ground are readily coupled to ground and become losses. The "theory" is that the horizontal currents leaving the top-center feed point are symmetrically equal and opposite (as in radial systems) and neutralize for minumum horizontal coupling-to-ground. Conversely, all the vertical components going downward in any and all parts of the truck box are additive, in addition to the fact that vertical currents are much less coupled to ground, and less ground loss. My apology if I am misrepresenting What I interpreted from Roy's comments. If so, perhaps he, or someone else will correct me. Note that with this system, there is no reason, or need for any additional bonding, or ground straps, (unless you assume that the hinge and latches on the tail-gate are insufficient). I had an aluminum tool box mounted at the rear of the box, but it did not touch the sides, so assume it had little effect. (Now that I think about it, I probably should have strapped its top edge to the top of the truck box, for an extra current path). My mast is concentric 1" each nearly 6' length. With loading coil and unique top hat, the mast is adustable for 13' legal limit traveling, or extended to 19' top height for extra performance while parked, or camping. Hoping to capture some attention from the High-power, Big-antenna discussion groups, I first went all out with the 19' high camping version with an especially Hi-Q loading coil, and extended with 75' of RG-58 (small coax) into the ham shack so that I could use a 1Kw linear. For the Hi-Q coil, I twisted two strands of #16 bare solid tinned copper wire (using an electric drill), and wound about 40 turns on a 4.5" diameter form with wax paper around it. I put a strip of clear RTV across the turns in two places. At a third place, I notched a piece of 3/4" PVC and supported each turn with RTV, with additional nylon strap at the first and last end turns, so it was essentially and air-wound dielectric between turns. The coil length was about 9" for a 2:1 L/W ratio. I believe the inductance was about 80 microhenries. The mast portion to the bottom of the coil (camping version) was about 10'-10" and the coil terminals were about 10" apart. The "unique" capacitive-hat was cylinder-like, and resembles an upside down waste basket of 1/2" square grids of galvanized wire (i.e. 1/2" hardware cloth). #14 copper clad steel wire is tack soldered in several places to provide more rigidity, as well as minimizing corona losses. Dimensions are about 1' diameter and 14" deep. It is attached to the top of the coil by four struts about 12" long (#14 copper-clad steel) angling to the center at the top of the coil. Physically, the coil/tophat assembly is supported by a section of 3/4" PVC which goes from the top of the capacitive-hat (actually the bottom of the "upside-down waste basket), down to overlap the 1" mast, and is "grooved" and clamped with hose-clamps. For adjusting the concentric masts, the lower one is cut about half way thru about 1/2" down an with a slit opening to allow a hose clamp to compress it to the upper mast for adjusting height. Admittedly, the 13' road version is a little ugly for road travel unless you're strongly motivated. I used black nylon guy ropes (found at Menards and are about the size of flat shoe laces) which are not so noticeable and conveniently attach to the four "post holes" in the truck bed. The low wind resistance of the 1/2" mesh is low enough for high speed driving. But the Camping version should be quite acceptable for parked, or camping. The final conclusion among a 75 meter discussion group who have years of almost nightly activity among members who use high power and and nearly optimum antenna systems, was that the performance was surprisingly similar to that of several of the members of the group, and exceeding some. I only used it one nite with the 13' drive version before I moved the truck, but it also got surprisingly good results. Of course I realize that hams become jaded by the many claims they hear about antenna performance so they will factor that into this description also. I forgot to mention that the "capacitive-match" method that I used across the feed-point required about 1200 picofarad. This is good news because we know that the actual radiation resistance is quite low (perhaps 2 to 5 ohms?), and any feed-point impedance above that represents loss. In the L-match equation, we know that the lower the feedpoint resistance, the higher shunt C is required ......i.e. the more C required, the better. Final question for my info: (perhaps for Roy Lewallen)........ ....if I model this on EZNEC with a 1" diameter dipole with radial systems attached at both ends (about 3' spokes), in Free Space with zero loss, and of course about 3.9 MHz, source at center, wouldn't the resistive portion represent the acutal radiation resistance? Article: 224661 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Tue, 23 May 2006 15:35:03 -0500 Message-ID: <24584-447371F7-1838@storefull-3256.bay.webtv.net> References: <1276ftr2cm9h294@corp.supernews.com> Roy Lewallen, W7EL wrote: "Am I mistaken, but is this not a clear statement that a copper or aluminum shield will block magnetic flux along with explanation of why it happens?" Yes. And now the rest of the story which I`ve already posted several times. At the bottom of page 38 in Terman`s 1955 edition; "It is possible to shield slectrostatic flux WITHOUT simultaneously affecting the magnetic field by surrounding the space to be shielded with a conducting cage that is made in such a way as to provide NO low-resistance path for the flow of eddy currents, while at the same time offering a metallic terminal upon which electrostatic flux can terminate." I invited readers to look at page 43 in the same book where: "A grid of wires such as shown in the accompanying figure will provide electrostatic shielding WITHOUT magnetic shielding---." I also said that similar grids (metal picket fences) were used in AM broadcast stations I`d worked in to eliminate capacitive coupling to the antennas which would otherwise favor harmonics of the broadcast frequency. W8JI is yet desiring to drive a stake in the heart of the "myth" that E&H fields are separable if even for an instant. He is dead wrong. The magnetic field alone does quite well in transferring all the wave`s energy through a special transformer which completely bars the electric field. Of course, current in the transformer`s secondary produces a voltage and the E-field is immediately restored. This is not witchcraft. In free-space the electric field and the magnetic field are repeatedly exchanging all the energy back and forth. It keeps the wave going. At a short or open on a transmission line energy is not lost. It is merely transferred for an instant into the surviving field. Similarly, all the energy can be transferred through the electric field with zero magnetic coupling. Imagine two separately shielded coils. Now, use a coupling capacitor to transfer the energy from one coil to the other. Voila! E-field transfer with zero magnetic coupling. It`s no myth. It`s a fact. Best regards, Richard Harrison, KB5WZI Article: 224662 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: FIGHT! FIGHT! FIGHT! References: <6571-446B5528-802@storefull-3251.bay.webtv.net> <12758v1nbaq09f5@corp.supernews.com> <3BDcg.29574$Lm5.3231@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 23 May 2006 21:01:58 GMT Cecil Moore wrote: > John - KD5YI wrote: > >> I thought there were two traveling waves, forward and reverse, with >> the reverse wave being a reflection of the forward wave from the end >> of the antenna. I thought that the total current was the sum of the >> two waves, could be measured with an ammeter, and that it could be >> referred to as the standing wave. > > > If the antenna were lossless, that would be true. However, the > antenna loses RF energy to radiation, ground, I^2*R, etc. Since > the same thing is true of a transmission line, let's first look > at a transmission line. > > Let's say we measure (at the tuner) > a forward power of 100 watts and a reflected > power of 80 watts. We can assume that the losses in the line > and the power delivered to the load add up to 20 watts. The > 20 watts can be associated with a pure forward traveling wave. > The other 80 watts of the forward power and the 80 watts of > reflected power can be associated with a pure standing wave. > The equations for such would look something like this. > > Itot = Ifor*cos(kx+wt) + Iref*cos(kx-wt) = > > Itot = I1*cos(kx+wt) + I2*cos(kx)*cos(wt) > > I1 would be considered to be the part of the traveling wave that > is delivering net power to the load. I2 would be considered to be > the standing wave current delivering no net power to the load. > It's just another way of mathematically partitioning the currents. > > Let's assume for the sake of discussion that the forward wave at > the antenna feedpoint is 100 watts and the reflected wave at the > antenna feedpoint is 80 watts. That means there are 20 watts of > total losses. We can partition the currents in the same way that > we did in the transmission line. > > Incidentally, if we assume the antenna is 1/2 wavelength with a > Z0 of 600 ohms, we can calculate the feedpoint impedance just as > if it were a piece of transmission line with a resistive termination. > Anybody want to try that exercise? What impedance is seen looking > into a 600 ohm 1/4WL open stub when the forward power is 100 watts > and the reflected power is 80 watts? > >> Are you now saying that the standing wave and the reverse wave are the >> same wave? > > > The reverse wave is half of the standing wave. The other half of > the standing wave is part of the forward wave. One might say that > the energy in the reverse wave neutralizes the ability of the > forward wave to deliver that same amount of energy to the load. > And indeed, we know the power delivered to the load is the forward > power minus the reflected power. Never mind. Article: 224663 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Tue, 23 May 2006 15:51:16 -0500 Message-ID: <24584-447375C4-1839@storefull-3256.bay.webtv.net> References: Cecil, W5DXP wrote: "Does a 60 Hz magnetic field travel virtually unimpeded through a coaxial shield?" Surely many readers have toiled with shielded audio cables similar to coax and they know the answer is yes, if the shield is broken (this often happens at the ends of the cable). Best regards, Richard Harrison, KB5WZI Article: 224664 of rec.radio.amateur.antenna Message-ID: From: jimp@specsol.spam.sux.com Subject: Re: sgc dipole? References: <1148390757.341256.120320@i40g2000cwc.googlegroups.com> <1276n13d85ld919@corp.supernews.com> Date: Tue, 23 May 2006 21:15:02 GMT Gary Schafer wrote: > >When used to center-feed a dipole, making the ground-side leg longer > >than the hot-side leg increases the capacitance to ground on that side > >and may tend to mimic the environment for which the tuners were really > >designed. > > > It is probably because those tuners do not do well with a resonant > antenna. With one legg longer than the other there is more chance > that the antenna will be reactive and make the tuner happier. > 73 > Gary K4FMX Maybe with dipoles, but my SGC has no problems with resonance on my vertical. FWIW, the vertical is resonant by itself on 40M and has a relay switched loading coil for 80M I put in before I got the SGC. With the loading coil out, the SGC has no problems 80M to 10M. With the loading coil in, 160M to 20M. Normal operation is loading coil in for 160M and 80M. -- Jim Pennino Remove .spam.sux to reply. Article: 224665 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Tue, 23 May 2006 14:16:01 -0700 Message-ID: <1276uslo9amil26@corp.supernews.com> References: <1276ftr2cm9h294@corp.supernews.com> <24584-447371F7-1838@storefull-3256.bay.webtv.net> Richard Harrison wrote: > Roy Lewallen, W7EL wrote: > "Am I mistaken, but is this not a clear statement that a copper or > aluminum shield will block magnetic flux along with explanation of why > it happens?" > > Yes. And now the rest of the story which I`ve already posted several > times. > > At the bottom of page 38 in Terman`s 1955 edition; > "It is possible to shield slectrostatic flux WITHOUT simultaneously > affecting the magnetic field by surrounding the space to be shielded > with a conducting cage that is made in such a way as to provide NO > low-resistance path for the flow of eddy currents, while at the same > time offering a metallic terminal upon which electrostatic flux can > terminate." > > I invited readers to look at page 43 in the same book where: > "A grid of wires such as shown in the accompanying figure will provide > electrostatic shielding WITHOUT magnetic shielding---." > > I also said that similar grids (metal picket fences) were used in AM > broadcast stations I`d worked in to eliminate capacitive coupling to the > antennas which would otherwise favor harmonics of the broadcast > frequency. > > W8JI is yet desiring to drive a stake in the heart of the "myth" that > E&H fields are separable if even for an instant. He is dead wrong. Certainly the E or H field can disappear for part of a cycle. This happens routinely in a transmission line or in free space, as the energy is swapped back and forth between the two components. Tom has never said this is not so. And for whole cycles you can locally change the ratio of E/H, but you cannot separate them. Maxwell's equations show this. And if you do change the ratio of E/H, the normal free space ratio is restored within a small distance. > The magnetic field alone does quite well in transferring all the wave`s > energy through a special transformer which completely bars the electric > field. Of course, current in the transformer`s secondary produces a > voltage and the E-field is immediately restored. Yes. And does this restored E field not occupy the space between the winding and the wire grid? If so, how can you tell that the grid has "stopped" the E field if it exists on both sides of the grid? > This is not witchcraft. In free-space the electric field and the > magnetic field are repeatedly exchanging all the energy back and forth. > It keeps the wave going. With this I totally agree. That explanation is related to why you can't simply remove one component or the other. > At a short or open on a transmission line energy is not lost. It is > merely transferred for an instant into the surviving field. > > Similarly, all the energy can be transferred through the electric field > with zero magnetic coupling. Imagine two separately shielded coils. Now, > use a coupling capacitor to transfer the energy from one coil to the > other. Voila! E-field transfer with zero magnetic coupling. It`s no > myth. It`s a fact. It's a myth that there's no magnetic field in the space between a capacitor's plates. Roy Lewallen, W7EL Article: 224666 of rec.radio.amateur.antenna From: helmsman Subject: Re: Is the little ball on top of my antenna the ionsphere? Date: Tue, 23 May 2006 17:36:12 -0400 Message-ID: References: On Tue, 23 May 2006 12:35:45 -0500, clifto wrote: >Ed wrote: >> Jay wrote in >> news:jOrcg.651$Sf2.175@newsread1.news.pas.earthlink.net: >> >>> I put the ball to a metal grinder and I could easily see an outer F >>> layer and then the E layer. I couldn't find a D layer, but it was >>> dark outside and there's not supposed to be a D layer at night. Neat >>> how antenna's can be manufactured to do that. >>> >>> Just passed my tech and General on Sunday so I'll be on the bands as >>> soon as I find out my callsign and get an ionsphere for my antenna. I >>> destroyed the old one on the grinder and I hear you need a good >>> ionsphere to shoot good skip and hear far away stations. Reception has >>> been really shitty lately without the ionsphere. I looked through the >>> last 4 issues of QST and I couldn't find anyone selling ionsphere's. >>> Where can I get one, or do I have to buy a whole new antenna? >>> >> >> You don't need a new one. The old one probably got stuck in your coax >> by back-feed when you were grinding. Just get an RF brush and give your >> coax a few swipes and the ionosphere should pop right back out! > >Don't forget the electron grease. And the High Falutin Rootin Tootin Valve! Article: 224667 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 16:43:02 -0500 Message-ID: <21363-447381E6-27@storefull-3257.bay.webtv.net> References: <1276ff6itsva2ca@corp.supernews.com> Roy, W7EL wrote: "I`m sure that somewhere in one of your texts you can find the definition of linear as applied to networks." Right. From "The Penguin Desk Encyclopedia of Science and Mathematics": "Linear (algebra) An equation or function of the form ax + by + c = 0 or f(x) = mx +b is called linear because its graph is a line. This has been generalized to a concept called linear combination, which is the sum of 2 or more entities with each multiplied by some number (with not all numbers being 0). Linear combinations of vectors, equations, and functions are commonly employed." I think that definition is broad enough to cover the representations I made in my postings. Best regards, Richard Harrison, KB5WZI Article: 224668 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 15:07:26 -0700 Message-ID: <12771t2jo3c5p2b@corp.supernews.com> References: <1276ff6itsva2ca@corp.supernews.com> <21363-447381E6-27@storefull-3257.bay.webtv.net> I can only hope that some of the readers understand. Roy Lewallen, W7EL Richard Harrison wrote: > Roy, W7EL wrote: > "I`m sure that somewhere in one of your texts you can find the > definition of linear as applied to networks." > > Right. From "The Penguin Desk Encyclopedia of Science and Mathematics": > > "Linear (algebra) An equation or function of the form ax + by + c = 0 > or f(x) = mx +b is called linear because its graph is a line. This has > been generalized to a concept called linear combination, which is the > sum of 2 or more entities with each multiplied by some number (with not > all numbers being 0). Linear combinations of vectors, equations, and > functions are commonly employed." > > I think that definition is broad enough to cover the representations I > made in my postings. > > Best regards, Richard Harrison, KB5WZI > > Article: 224669 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT? Here is another W8JI myth bone! References: <24584-447375C4-1839@storefull-3256.bay.webtv.net> Message-ID: Date: Tue, 23 May 2006 22:19:23 GMT Richard Harrison wrote: > Cecil, W5DXP wrote: > "Does a 60 Hz magnetic field travel virtually unimpeded through a > coaxial shield?" > > Surely many readers have toiled with shielded audio cables similar to > coax and they know the answer is yes, if the shield is broken (this > often happens at the ends of the cable). > > Best regards, Richard Harrison, KB5WZI > The skin depth of copper at 60 hertz is supposed to be 8.53mm. That's too thick to make a practical shield. No wonder they're having problems. 73, Tom Donaly, KA6RUH Article: 224670 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Tue, 23 May 2006 17:14:19 -0500 Message-ID: <21360-4473893B-1884@storefull-3257.bay.webtv.net> References: <1276uslo9amil26@corp.supernews.com> Roy, W7EL wrote: "It`s a myth that there`s no magnetic field in the space between a capacitor`s plates." Maxwell`s great speculation was that "displacement current", as between a capacitor`s plates, produced magnetic flux as does conduction current. His speculation is now proved. Best regards, Richard Harrison, KB5WZI Article: 224671 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT! FIGHT! FIGHT! References: <1276ff6itsva2ca@corp.supernews.com> <21363-447381E6-27@storefull-3257.bay.webtv.net> Message-ID: Date: Tue, 23 May 2006 22:26:28 GMT Richard Harrison wrote: > Roy, W7EL wrote: > "I`m sure that somewhere in one of your texts you can find the > definition of linear as applied to networks." > > Right. From "The Penguin Desk Encyclopedia of Science and Mathematics": > > "Linear (algebra) An equation or function of the form ax + by + c = 0 > or f(x) = mx +b is called linear because its graph is a line. This has > been generalized to a concept called linear combination, which is the > sum of 2 or more entities with each multiplied by some number (with not > all numbers being 0). Linear combinations of vectors, equations, and > functions are commonly employed." > > I think that definition is broad enough to cover the representations I > made in my postings. > > Best regards, Richard Harrison, KB5WZI > > You're right in a certain mathematical sense, but that definition isn't correct, as Roy pointed out, in defining superposition. 73, Tom Donaly, KA6RUH Article: 224672 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Tue, 23 May 2006 15:31:13 -0700 Message-ID: <127739l4kf0e73a@corp.supernews.com> References: <1276uslo9amil26@corp.supernews.com> <21360-4473893B-1884@storefull-3257.bay.webtv.net> Richard Harrison wrote: > Roy, W7EL wrote: > "It`s a myth that there`s no magnetic field in the space between a > capacitor`s plates." > > Maxwell`s great speculation was that "displacement current", as between > a capacitor`s plates, produced magnetic flux as does conduction current. > His speculation is now proved. Yes. So how does a capacitor between two inductors constitute "E-field transfer with zero magnetic coupling" as you stated? Roy Lewallen, W7EL Article: 224673 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: FIGHT? Here is another W8JI myth bone! References: <1276ftr2cm9h294@corp.supernews.com> <24584-447371F7-1838@storefull-3256.bay.webtv.net> Message-ID: Date: Tue, 23 May 2006 22:35:54 GMT Richard Harrison wrote: > Roy Lewallen, W7EL wrote: > "Am I mistaken, but is this not a clear statement that a copper or > aluminum shield will block magnetic flux along with explanation of why > it happens?" > > Yes. And now the rest of the story which I`ve already posted several > times. > > At the bottom of page 38 in Terman`s 1955 edition; > "It is possible to shield slectrostatic flux WITHOUT simultaneously > affecting the magnetic field by surrounding the space to be shielded > with a conducting cage that is made in such a way as to provide NO > low-resistance path for the flow of eddy currents, while at the same > time offering a metallic terminal upon which electrostatic flux can > terminate." > > I invited readers to look at page 43 in the same book where: > "A grid of wires such as shown in the accompanying figure will provide > electrostatic shielding WITHOUT magnetic shielding---." > > I also said that similar grids (metal picket fences) were used in AM > broadcast stations I`d worked in to eliminate capacitive coupling to the > antennas which would otherwise favor harmonics of the broadcast > frequency. > > W8JI is yet desiring to drive a stake in the heart of the "myth" that > E&H fields are separable if even for an instant. He is dead wrong. > > The magnetic field alone does quite well in transferring all the wave`s > energy through a special transformer which completely bars the electric > field. Of course, current in the transformer`s secondary produces a > voltage and the E-field is immediately restored. > > This is not witchcraft. In free-space the electric field and the > magnetic field are repeatedly exchanging all the energy back and forth. > It keeps the wave going. > > At a short or open on a transmission line energy is not lost. It is > merely transferred for an instant into the surviving field. > > Similarly, all the energy can be transferred through the electric field > with zero magnetic coupling. Imagine two separately shielded coils. Now, > use a coupling capacitor to transfer the energy from one coil to the > other. Voila! E-field transfer with zero magnetic coupling. It`s no > myth. It`s a fact. > > Best regards, Richard Harrison, KB5WZI > When did you perform this experiment, Richard? (Perfectly shielding two coils and then coupling them with a capacitor.) And how did you manage to shield them if, as you seem to think, the magnetic fields are capable of penetrating the shield? 73, Tom Donaly, KA6RUH Article: 224674 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 18:59:50 -0400 Message-ID: <12774tss6icpt17@corp.supernews.com> References: <1276ff6itsva2ca@corp.supernews.com> <21363-447381E6-27@storefull-3257.bay.webtv.net> <12771t2jo3c5p2b@corp.supernews.com> Oh my goodness! The critical qualification and definition has been provided by Roy. Roy and Richard then proceeded to nail the subject to the proverbial wall. It is time to pause in grading exams to remind that analytic geometry and circuit theory are not the same thing. In circuit theory (and practice) a circuit/network/or-whatever is linear if, and only if, superposition is satisfied. If superposition is satisfied, then the circuit in question is linear. This concept also has utility in some mechanical structures. In English, it is not uncommon for a word to have quite different meanings depending on where it is used. We all know this. Even when discussing active devices such as BJTs and FETs one finds the word "saturation" used differently depending on the device. Obviously, large enough signals applied to any network that appears to be linear with smaller signals will melt same - letting out the smoke that was placed therein at the factory. Obviously, there are degrees of linearity. A footnote is always understood to say: such-and-such network is acceptably linear for signals larger than A and smaller than B. ... thus ends the lesson. 73, Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Roy Lewallen" wrote in message news:12771t2jo3c5p2b@corp.supernews.com... > I can only hope that some of the readers understand. > > Roy Lewallen, W7EL > Article: 224675 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 19:11:00 -0400 Message-ID: <12775irg2ot70e9@corp.supernews.com> References: <12757m7m6v342f0@corp.supernews.com> <24025-4473145E-1862@storefull-3258.bay.webtv.net> Dear Richard: I have had occasion to note to students that some of what they call music would not be noticeably modified by being amplified by a amplifier having a great deal of distortion. Your point is right on target. 73, Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Richard Clark" wrote in message news:d6e672thneibb62iidcfvp4lqi46jmed8v@4ax.com... > On Tue, 23 May 2006 08:55:42 -0500, richardharrison@webtv.net (Richard > Harrison) wrote: > > >f(x) = y = mx + b is called linear because its graph is a straight line. > > Hi Richard, > > Try listening to Mozart with a speaker driven with such a "linear" > gain device. [Some things are so simple, they defy further analysis.] > > This, again, goes to the matter of a finely staged distortion trial > with tone-deaf judges. > > 73's > Richard Clark, KB7QHC Article: 224676 of rec.radio.amateur.antenna From: "Kevin & Natalia" Subject: Re: Control Unit for Home Built Rotator from Pitch-Prop Motor Date: Wed, 24 May 2006 11:52:31 +1200 Message-ID: <1148428168.920547@ftpsrv1> References: <1148377755.519950@ftpsrv1> Hi Tim, My electronics skills are fairly good, I have built many projects over the time. What I was wanting to do, is have a control box in the shack with a readout and left/right controls. And have the provision to also be able to have a PC control it. I like the Pitch-prop motor, as it is strong, and can be controlled easy. The way I control it at the moment, is via a 2 voltage system. The pitch-prop runs at 36volts for full speed, and when I wish to slow it down for small movements, I use a second set of controls at 15volts. Not the best way of doing it, but it works. I then look out the window and see where it is pointing. I know where N, E, S, W are on my section. As to price on the parts, I would like to keep it down to around a couple of hundred dollars. :) Regards and thanks for your input. Kevin, ZL1KFM www.qsl.net/zl1hk "Tim Wescott" wrote in message news:hOmdnZarFMOuh-7ZnZ2dnUVZ_vqdnZ2d@web-ster.com... >> >> > Excepting the readout, this should be a fairly routine motor control > problem. Depending on what you want to do your control box could be as > simple as a current-limited power supply and a couple of switches or as > complex as a fully fed-back motion control system. > > How's your electronics skills, and how fancy do you want it to be? > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com > > Posting from Google? See http://cfaj.freeshell.org/google/ > > "Applied Control Theory for Embedded Systems" came out in April. > See details at http://www.wescottdesign.com/actfes/actfes.html Article: 224677 of rec.radio.amateur.antenna Subject: Re: sgc dipole? From: Ed References: <1148390757.341256.120320@i40g2000cwc.googlegroups.com> <1148399563.958468.40310@j55g2000cwa.googlegroups.com> <1148428770.229442.10210@i40g2000cwc.googlegroups.com> Message-ID: Date: 24 May 2006 00:03:09 GMT > > If I have a different length on the case of the tuner compared to the > length on the hot terminal, how does that moderate impedance? Assuming you're speaking of a resonant dipole or verticle, it would seem to me that by doing that you are moving the feedpoint away from the 50 ohm (70 ohm?) feedpoint at the center.... and probably towards a higher impedance feedpoint. Not sure what effect that would have on those autotuners, but perhaps they work better with a bit higher impedance than 50 ohms? Ed K7AAT Article: 224678 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT? Here is another W8JI myth bone! References: <1276ftr2cm9h294@corp.supernews.com> <24584-447371F7-1838@storefull-3256.bay.webtv.net> <1276uslo9amil26@corp.supernews.com> Message-ID: Date: Wed, 24 May 2006 00:24:12 GMT Roy Lewallen wrote: > It's a myth that there's no magnetic field in the space between a > capacitor's plates. What quantum particles support that magnetic field? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224679 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT? Here is another W8JI myth bone! References: <24584-447375C4-1839@storefull-3256.bay.webtv.net> Message-ID: <_KNcg.35204$Lm5.4326@newssvr12.news.prodigy.com> Date: Wed, 24 May 2006 00:26:34 GMT Tom Donaly wrote: > The skin depth of copper at 60 hertz is supposed to be 8.53mm. That's > too thick to make a practical shield. No wonder they're having problems. So 60 Hz magnetic fields penetrate shielded coax? -- 73, Cecil http://www.qsl.net/w5dxp Article: 224680 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 19:21:45 -0500 Message-ID: <12369-4473A719-2081@storefull-3253.bay.webtv.net> References: Tom, KA6RUH wrote: "You`re right in a certain mathematical sense, but that definition isn`t correct as Roy pointed out in defining superposition." Or in conjugate matching for that matter. The discussion was: Is an antenna a linear device, meaning does it produce amplitude distortion? Amplitude distortion comes from a nonlinear relation between imput and output. It has nothing to do with has the amplitude grown larger or smaller in the antenna? I think the majority of antennas have an output which is a reasonable approximation in form to their input. That goes for frequencies too. The response won`t be the same for all frequencies, but you`re not likely to find new frequencies on the output of the antenna that aren`t on its input. Superposition says that when a number of voltages (distributed in any manner throughout a linear network) are applied to the network simultaneously, the current that flows is the sum of the component currents that would flow if the same currents had acted individually. As Cecil said, nonlinearity produces new frequencies. Good antennas don`t do that, superposition or not. Best regards, Richard Harrison, KB5WZI Article: 224681 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: sgc dipole? Message-ID: References: Date: Wed, 24 May 2006 01:33:37 GMT On Mon, 22 May 2006 23:19:25 GMT, ml wrote: >hi > >I was wondering a few things i read about in my sgc tuner manual about >dipoles > > >a) they say or sorta recomend that if your making a simple horiz ctr fed >dipole, it's 'best' to have one leg longer This might be related to the sometimes heard myth / nonsense that a half wave dipole does not need a 1:1 balun at the feedpoint, but that one leg should be made a little longer than the formula length to compensate for the feedline common mode current. I don't know the source of this concept, but I hear it from time to time from avid readers, usually introduced with "of course, as everyone knows..." . Owen -- Article: 224682 of rec.radio.amateur.antenna From: "Jerry Martes" References: <6hAcg.5443$oa3.1513@trnddc08> Subject: Re: Question about the uses for an antenna design Message-ID: Date: Wed, 24 May 2006 01:34:09 GMT Hi Cecil I'll top post to your question and the other repliers. I have *NO* thoughts of money transfer. This is not an invention. I merely assembled a set of four dipoles so they'd produce a pattern thats sensitive to RHCP thruout the entire hemisphere. I'd probably even pay to get someone to try building and testing one of these Cross antennas. I just dont know what it is good for except receiving signals from NOAA weather satellites. The Double Cross does look alot like a Lindenblad. But, the dipoles are tilted more sharply toward vertical. Cecil, you ask about how this antenna differs from a turnstile. The four dipole Double Cross has a pattern that has a much greater sensitivity to RHCP toward the horizon than the turnstile. it even has sensivity to RHCP at the horizon whereas the Turnstile is linear. The fundamental concept (Cross concept) is two dipoles crossed at 90 degrees, both tilted from vertical, spaced about 90 degrees and fed in phase. That produces circular polarization toward the horizon in two opposite directions. The Double Cross, which looks a little like the Lindenblad, is two Cross antennas mounted together. One Cross is fed 90 degrees later than the other. I have been trying to develop this concept for more than a year and have stumbled on a configuration that really works for receiving NOAA polar orbiting satellite signals. The GEO community has rejected the double Cross as its being "not perfect". I dont know anyone else who'd have interest in an antenna thats really easy to make and will work even when built somewhat differently from some exact model. A guy in England has been publishing all the NOAA satellite images I record here in Los Alamitos. The images can be seen at http://www.sattraxuk.com/imagestothewestaptdecoder/daily/index.html The images on this site begin and end at zero degree elevation of the satellite, independent of the received signal strength. So, the viewer can be assured that the images from this Double Cross are a good indication of the sensitivity of the antenna and the amount of pattern nilling. I have some text written to try to describe the concept. It is really difficult for me to know if that text is understandable. Nobody has ever asked me to clarify any of it. That is - I get no feedback. I just cant find anyone interested in my project. Oh, I have located one guy who thinks the Double Cross has merit. He is Patrik Tast, and lives in Finland. So, if anyone has interest, or knows of anyone who'd like more info on the Double Cross concept, I'd sure like to share this with them. Thanks for the interest Jerry j.jmartes@verizon.net KD6JDJ 33.8 N 118.0 W "Cecil Moore" wrote in message news:ywFcg.76009$_S7.28525@newssvr14.news.prodigy.com... > Jerry Martes wrote: >> I have determined a way to feed four dipoles to provide good horizon to >> horizon coverage at all angles for circularly polarized signals. > > Hi Jerry, how is your antenna superior to a two-dipole turnstile? > -- > 73, Cecil http://www.qsl.net/w5dxp Article: 224683 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 21:35:37 -0400 Message-ID: <1277e20re0d5kbe@corp.supernews.com> References: <12757m7m6v342f0@corp.supernews.com> <24025-4473145E-1862@storefull-3258.bay.webtv.net> <12775irg2ot70e9@corp.supernews.com> Dear Richard: Last week's lab job in both Electronics I and II (at different levels) explored just this issue. How great it is to have really good scopes and a spectrum analyzer in a student tab. 73 Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Richard Clark" wrote in message news:fv6772du3eoj1g2onl6vidn5l3l5ijjuuq@4ax.com... > On Tue, 23 May 2006 19:11:00 -0400, "J. Mc Laughlin" > wrote: > > >Dear Richard: > > > >I have had occasion to note to students that some of what they call music > >would not be noticeably modified by being amplified by a amplifier having a > >great deal of distortion. > > > > Your point is right on target. > > Hi Mac, > > My point may have been on target, but the specifics left an escape for > those quick enough to pick up on it. In fact, I would speculate that > most audio (as do RF) amplifiers exhibit the gain characteristic of > f(x) = y = mx + b > and this is called class AB. When you build an amp employing two of > them in a push-pull configuration the constants b negate each other > and the 2mx remains. > > Of course, the push-pull configuration is built to nullify the > distortion of this "linear" curve. > > The single power supply Op Amp also suffers from > f(x) = y = mx + b > with the output floating at half the supply voltage - this has got to > be an application killer if it goes straight to the speakers without > removing the b with a capacitor. > > 73's > Richard Clark, KB7QHC Article: 224684 of rec.radio.amateur.antenna From: John Barnard Subject: Re: Is the little ball on top of my antenna the ionsphere? References: Message-ID: Date: Wed, 24 May 2006 02:13:44 GMT clifto wrote: > Ed wrote: > >> Jay wrote in >> news:jOrcg.651$Sf2.175@newsread1.news.pas.earthlink.net: >> >> >>> I put the ball to a metal grinder and I could easily see an outer F >>> layer and then the E layer. I couldn't find a D layer, but it was >>> dark outside and there's not supposed to be a D layer at night. Neat >>> how antenna's can be manufactured to do that. >>> >>> Just passed my tech and General on Sunday so I'll be on the bands as >>> soon as I find out my callsign and get an ionsphere for my antenna. I >>> destroyed the old one on the grinder and I hear you need a good >>> ionsphere to shoot good skip and hear far away stations. Reception has >>> been really shitty lately without the ionsphere. I looked through the >>> last 4 issues of QST and I couldn't find anyone selling ionsphere's. >>> Where can I get one, or do I have to buy a whole new antenna? >>> >>> >> You don't need a new one. The old one probably got stuck in your coax >> by back-feed when you were grinding. Just get an RF brush and give your >> coax a few swipes and the ionosphere should pop right back out! >> > > Don't forget the electron grease. > > Was that the stuff that replaced the etheric oil? JB Article: 224685 of rec.radio.amateur.antenna From: Jim - NN7K Subject: Re: What happens if you pipe the output of one radio in to 2 amps? References: Message-ID: Date: Wed, 24 May 2006 02:30:02 GMT Depends--, if in phase, Both INPUT, and OUTPUT, would add (double power, if SAME power on both, Also would add, if 180 degrees OUT of Phase, both Input, and Output. And this would be the same as with Push-Pull amp (both input, and output). but if In Phase, on input, and OUT of Phase, on Output,or vice versa, theoretically, would result in 0 Output. And, if in different phases, probably would make a great interference source!!! (distortion, intermods, harmonics, oddball mixes, ect!) Jim NN7K Slow Code wrote: > Ponder This wrote in > news:ohm6725evd9edtv29nelqspiu7ihda94ve@4ax.com: > > >> >> Just cusrious... >> >>What happens if you pipe the output of one radio in to 2 different >>amplifiers, and then take the output of the two amps and send them to >>two identical vertical antennas spaced a half wave apart and with >>equal length feedlines from the amplifiers. >> >>Will the output of the two amplifiers add together in directions where >>the signal is in phase, or will it act like two different signals and >>interfere with each other? >> >>-Curious > Article: 224686 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <12369-4473A719-2081@storefull-3253.bay.webtv.net> Message-ID: Date: Wed, 24 May 2006 03:15:36 GMT Richard Clark wrote: > Appeals of authority that are pegged to Cecil are like trying to tread > water with a concrete life preserver. Your logic is blighted by a > forced conclusion that has nothing to do with the obvious observation > that antennas, as transmission lines, are quite evidently non-linear > in their characteristic Z. This has been demonstrated and is historic > from sources that even Terman's accepts. There exist transmission lines with a changing Z0 along their lengths. Those transmission lines are linear systems. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224687 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT? Here is another W8JI myth bone! References: <24584-447375C4-1839@storefull-3256.bay.webtv.net> <_KNcg.35204$Lm5.4326@newssvr12.news.prodigy.com> Message-ID: <0iQcg.14095$fb2.5115@newssvr27.news.prodigy.net> Date: Wed, 24 May 2006 03:20:28 GMT Michael Tope wrote: > "Cecil Moore" wrote: >>So 60 Hz magnetic fields penetrate shielded coax? > > Cecil, if ever I had the feeling that I was about to answer a loaded > question, this is it, but here goes anyway - "Yes, I believe a 60 Hz > magnetic field impinging on a piece of shielded coax would penetrate > the shield of that coax significantly if the shield were made of a > non-ferrous conductor." It's not a loaded question. I just always assumed that coax would shield the system from 60 Hz noise and I guess I was wrong. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224688 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1276ftr2cm9h294@corp.supernews.com> <24584-447371F7-1838@storefull-3256.bay.webtv.net> Subject: Re: FIGHT? Here is another W8JI myth bone! Message-ID: Date: Tue, 23 May 2006 23:34:30 -0400 "Richard Harrison" wrote > > Similarly, all the energy can be transferred through the electric field > with zero magnetic coupling. Imagine two separately shielded coils. Now, > use a coupling capacitor to transfer the energy from one coil to the > other. Voila! E-field transfer with zero magnetic coupling. It`s no > myth. It`s a fact. > > Best regards, Richard Harrison, KB5WZI > I wonder how the gurus 'splain the different behavior of vertical vs. horizontally polarized antennas, where E field determines the way signals reflect and form the pattern. If E and H fields are so "inseparable" there should be no difference, right? They are ignoring behavior of E and H fields within the near field of antennas and workings of the shield. Another example of shield's performance was when I had small shielded loop next to the Beverage. The combination gave better S/N performance and better signal levels than each of them alone. Again, shield performing shielding function in the vicinity of near field of both antennas. Loops were tunable and performing as an antenna, shield was shielding from the near by interference and providing symmetry. FACTS - verifiable not subject to wild speculations about current crawling around the edge to inside of tubing, or antenna inside of electrostatic shield quitting to work as antenna because of "W8JI shield is antenna teachings". -- Yuri Blanarovich, K3BU, VE3BMV Article: 224689 of rec.radio.amateur.antenna From: m II Subject: Re: HF broadcasting antennas References: <5s84k3-2id.ln1@remote.clifto.com> Message-ID: Date: Wed, 24 May 2006 04:11:16 GMT clifto wrote: > I knee-jerk associated .hr with Hungary. Oops. Guess my Domainian is as > bad as my Hungarian. The Ace is Vulgarian...and he speaks it fluently. mike Article: 224690 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Tue, 23 May 2006 23:01:52 -0500 Message-ID: <23821-4473DAB0-118@storefull-3252.bay.webtv.net> References: Richard Clark wrote: "Demanding that "new frequencies" must exist AND then saying that they must be of such-and-such a magnitude to qualify is a hoot." Glad you got a kick out of that. It is not original. In analog microwave systems, often an baseband intermod monitor is used to alarm the operator that nonlinearity has arrived in his system. New frequencies have appeared and have reached a preset arbitrary amplitude sufficient to trigger an alarm. Nothing is perfect so there will always be some intermod. This requires setting a level of these intermod products which will trigger the alarm. This is a standard procedure. Best regards, Richard Harrison, KB5WZI Article: 224691 of rec.radio.amateur.antenna From: Buck Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Message-ID: <8kq772pcq2lkiqval3aj7qs1ki102ccep1@4ax.com> References: Date: Wed, 24 May 2006 01:13:52 -0400 >> What happens if you pipe the output of one radio in to 2 different >> amplifiers, and then take the output of the two amps and send them to >> two identical vertical antennas spaced a half wave apart and with >> equal length feedlines from the amplifiers. >> >> Will the output of the two amplifiers add together in directions where >> the signal is in phase, or will it act like two different signals and >> interfere with each other? >> >> -Curious I would assume the following: If you use a splitter with an equal length of coax to the two amps, you would be able to get 100 watts out >from the radio to be 50 watts into each amp. I would suspect that you would have double the power out to the antenna assuming you used the same length of coax from the amps to the antenna. Of course, you have to deal with impedance problems with the splitting of the coax, for example, two 50 ohm cables would result in 25 ohms to the amps. Not good. then the two 50 ohm outputs from the amps would result in 100 ohms to the antenna, not good again.... -- 73 for now Buck N4PGW Article: 224692 of rec.radio.amateur.antenna Date: Wed, 24 May 2006 00:58:38 -0600 From: BKR Subject: Re: Question about the uses for an antenna design References: <6hAcg.5443$oa3.1513@trnddc08> <1148395555.325411.197540@i39g2000cwa.googlegroups.com> Message-ID: <44740422@nntp.zianet.com> n3ox.dan@gmail.com wrote: > Is it something like the Lindenblad? > > http://www.phys.unsw.edu.au/~map/weather/notes/buildyourown/lindenblad.html > > I'm always interested in an antenna design. Making some drawings or > taking some photos (or both) and putting them up on a website with some > measurements is a fine way to publish your construction. > > If you are trying to make some money, I can help for some percentage to > be decided :-) > > Seriously, though, everyone would be interested in the concept. Put it > up on a webpage, even if just a couple of photos. I think QSL.net and > some other sites will give you hosting. > > 73, > Dan > N3OX > www.n3ox.net > I believe this idea has already been done and used at major airports for VHF communication. The ones I have seen have 4 dipoles on stalks, and each is 45 degrees from horizontal. They are used for aircraft in closs proximity to the field where polarization is unpredictable as craft enter, leave, and cross over the strip. Article: 224693 of rec.radio.amateur.antenna From: =?utf-8?b?Sm9uIEvDpXJlIEhlbGxhbg==?= Subject: Re: Yacht Rf ground and radials Date: 24 May 2006 10:08:21 +0200 Message-ID: <1m4pzfsv4a.fsf@persaunet.uninett.no> References: <447311d0_1@news.iprimus.com.au> Will writes: > I want to set up a hf antenna for my sailboat. > > I have read various guides from Icom etc. > > They suggest running copper foil to a Dynaplate and use sea water as > the ground. How can this work when the Dynaplate is below sea water? > > Is sea water equal to copper wire radials as a RF ground system? > > Does sea water make a good enough ground without radials? > > How can a piece of copper metal about 1 ft square equal several > radials laying on the boats deck? > > Why do i have to use copper foil when most other people suggest using > ordinary copper wire? > > Over seawater what would be the best number of radials to use > considering that maximum length i can run is 40 ft. I am planning to > use a backstay antenna with a SGC 230 Tuner. > > All ideas and comments appreciated. Well, I don't have personal experience with this. There is a chapter in the ARRL antenna book, and it basically agrees with ICOM. As to radials - two comments. First - how do you make sure that they don't get in the way. And that RF currents won't be a hazard to people. Second - there are plenty of wires on a yacht. How do the wires know whether or not they are supposed to act as radials? *If* there is a better alternative to the traditional backstay using seawater as ground, it might be the vertical dipole. Feeding would be tricky, but for single band operation, you could probably feed it like a J-Pole. I don't see how to make a multiband variant. And you get the high voltage points close to the deck, which doesn't sound like a good idea in a damp and salty environment. There are also people who hoist a horizontal dipole when needed. OK for recreational radio, not if you need to be able to communicate in rough weather. Of course, square riggers are beautiful, and you could use the yard-arms as a stacked yagi. 73 LA4RT Jon Article: 224694 of rec.radio.amateur.antenna From: =?utf-8?b?Sm9uIEvDpXJlIEhlbGxhbg==?= Subject: Re: sgc dipole? Date: 24 May 2006 10:15:03 +0200 Message-ID: <1mzmh7rg8o.fsf@persaunet.uninett.no> References: <1148390757.341256.120320@i40g2000cwc.googlegroups.com> <1148399563.958468.40310@j55g2000cwa.googlegroups.com> <1148428770.229442.10210@i40g2000cwc.googlegroups.com> w8ji@akorn.net writes: > n3ox.dan@gmail.com wrote: > > I expect there's not supposed to be any feedline between the antenna > > and the tuner in this installation, so I think that it probably is to > > moderate the impedance for a ham band antenna cut for the lowest band. > > If I have a different length on the case of the tuner compared to the > length on the hot terminal, how does that moderate impedance? May be they want the impedance on the second harmonic to be less *exciting*. If there is a length of lossy feedline between my resonant 80 m antenna and the tuner, and I try tuning up on 40 m, I won't fry my tuner. But if the tuner is at the feedpoint, the voltage gets extremely high. 73 LA4RT Jon Article: 224695 of rec.radio.amateur.antenna From: "Jerry Martes" References: <6hAcg.5443$oa3.1513@trnddc08> <1148395555.325411.197540@i39g2000cwa.googlegroups.com> <44740422@nntp.zianet.com> Subject: Re: Question about the uses for an antenna design Message-ID: Date: Wed, 24 May 2006 10:02:23 GMT "BKR" wrote in message news:44740422@nntp.zianet.com... > > > n3ox.dan@gmail.com wrote: >> Is it something like the Lindenblad? >> >> http://www.phys.unsw.edu.au/~map/weather/notes/buildyourown/lindenblad.html >> >> I'm always interested in an antenna design. Making some drawings or >> taking some photos (or both) and putting them up on a website with some >> measurements is a fine way to publish your construction. >> >> If you are trying to make some money, I can help for some percentage to >> be decided :-) >> >> Seriously, though, everyone would be interested in the concept. Put it >> up on a webpage, even if just a couple of photos. I think QSL.net and >> some other sites will give you hosting. >> >> 73, >> Dan >> N3OX www.n3ox.net >> > > > > I believe this idea has already been done and used at major airports for > VHF communication. The ones I have seen have 4 dipoles on stalks, and > each is 45 degrees from horizontal. They are used for aircraft in closs > proximity to the field where polarization is unpredictable as craft enter, > leave, and cross over the strip. Hi BKR That airport antenna is probably a Lindenblad. It has a serious "lack of sensitivity" toward zenith. That "null straight up" isnt important at an airport. I submit to you that, although this Cross concept is basic and simple, nobody has yet documented *anything* on it. The Quadrafilar Helix has the same general pattern characteristics as the Cross, but the Helix is alot more difficult for me to build and understand. In addition, the Cross can be made to have considerably more sensitivity toward the horizon than the Quad Helix. Jerry Article: 224696 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Wed, 24 May 2006 09:00:52 -0500 Message-ID: <17757-44746714-21@storefull-3257.bay.webtv.net> References: Richard Clark wrote: "Choose your own numbers, or find an authority to quote a quantitave response." If you can`t detect it, it might as well not exist. If you do detect it, it`s up to you to correct it or not. How many antennas have troubled you with new frequencies? Best regards, Richard Harrison, KB5WZI Article: 224697 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <17757-44746714-21@storefull-3257.bay.webtv.net> Message-ID: Date: Wed, 24 May 2006 14:34:19 GMT Richard Harrison wrote: > How many antennas have troubled you with new frequencies? Half a century ago, I installed a ceramic capacitor across the feedpoint of my dipole to change the resonant frequency. I'm sure it generated some new frequencies when it blew up and caught on fire. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 224698 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Date: Wed, 24 May 2006 10:06:21 -0500 Message-ID: <28598-4474766D-43@storefull-3255.bay.webtv.net> References: Curious wrote: "Will the output of two amplifiers add together in directions where the signal is in phase, or will it act like two different signals and therefore interfere with each other?" For stereo? The signals are coherent from two amplifiers or from one. Two close antennas fed the same signal in the same phase generally add broadside to the plane containing the antennas and cancel at right angles to the lobes containing the added signals. See page 91 of Kraus` 3rd efition of "Antennas" for: "Two Isotropic Point Sources of the Same Amplitude and Phase." Another example is the pair af CB antennas used by truckers, one on either side of the truck cab, to reinforce the signal fore and aft of the truck. The 1/2-wave dipole is another example. Its two elements have the same cuerrent amplitude and direction. Its lobes are broadside and its nulls are at right angles off the tips of the elements. Best regards, Richard Harrison, KB5WZI Article: 224699 of rec.radio.amateur.antenna Message-ID: <44748189.5DB376F1@antenna_dude.org> From: antenna_dude Subject: Re: Special Tower Bolts References: <84062$447302fc$ce6b49db$18022@COMTECK.COM> Date: Wed, 24 May 2006 15:53:47 GMT common bolt just like lug bolts used on your car to hold the weel on the hub. Article: 224700 of rec.radio.amateur.antenna From: "Jerry Martes" References: <6hAcg.5443$oa3.1513@trnddc08> <1148483679.078024.19470@i40g2000cwc.googlegroups.com> Subject: Re: Question about the uses for an antenna design Message-ID: Date: Wed, 24 May 2006 16:35:54 GMT wrote in message news:1148483679.078024.19470@i40g2000cwc.googlegroups.com... > Jerry, can you post a photo on a webpage somewhere? > > I think I get it... a single cross is like the driven elements of a > circularly polarized crossed yagi, the kind where you get the 90 degree > phasing by physical staggering of the elements. > > Since it has no reflectors or directors, it's bidirectional. If you > cross two Crosses and feed them 90 degrees out of phase you get a > more-or-less omnidirectional azimuth pattern. > > It is a pair of crossed dipoles fed as a turnstile. > > I personally would probably still call it a Lindenblad, but maybe the > phasing is different on the Lindenblad.. I think they're phased the > same way, though. > > Stick up a picture, if you can, or email to me... I'd like to see the > construction in case I'm missing something. > > 73, > Dan > N3OX Hi Dan The Lindenblad is quite alot different than the Cross. Perhaps my objection to having the Cross being considered to be a version of the Lindenblad is subjective. But, the two antennas are significantly different from each other. The Cross is not one particular antenna with exact dimensions. The Cross is more a concept. When two Cross antennas are nested together, they can be phased to provide sensitivity to circular polarized signals thruout the hemisphere and have good sensitivity toward the horizon. Jerry Article: 224701 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Date: Wed, 24 May 2006 11:41:41 -0500 Message-ID: <15322-44748CC5-24@storefull-3251.bay.webtv.net> References: Cecil, W5DXP wrote: "I wonder if two separate amps could maintain coherency under all conditions of supply voltage, temperature, humidity, etc." If reasonable control applies, it works. I built a rat-race, hybrid-ring, diplexer to parallel two identical shortwave broadcast transmitters. They were fed from the same RF oscillator and from the same audio source. Both were adjusted for nearly 100% modulation. The pair produced nearly 100 KW, fully modulated into the same antenna. It worked fine. No jerking around and little unbalanced energy dissipated into the dummy load. This was no sweat for the antennas which worked with our 100 KW transmitters every day. This is what you need to do when frequency shortages become acute. The votages in the transmitters were regulated by Sola transformers which had been shipped to us as 60 Hz transformers but reresonated on site for 50 Hz which was our European supply frequency. Best regards, Richard Harrison, KB5WZI Article: 224702 of rec.radio.amateur.antenna From: Roger Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Message-ID: References: Date: Wed, 24 May 2006 14:53:16 -0400 On Tue, 23 May 2006 23:05:56 GMT, Slow Code wrote: >Ponder This wrote in >news:ohm6725evd9edtv29nelqspiu7ihda94ve@4ax.com: > >> >> >> Just cusrious... >> >> What happens if you pipe the output of one radio in to 2 different >> amplifiers, and then take the output of the two amps and send them to >> two identical vertical antennas spaced a half wave apart and with >> equal length feedlines from the amplifiers. >> >> Will the output of the two amplifiers add together in directions where >> the signal is in phase, or will it act like two different signals and >> interfere with each other? >> >> -Curious > > >Why would you do that? It's the same as just splitting a single output >from the radio. Depending on spacing and phase you can get of variety of >different radiation patterns. You don't need to split it between two >amps. I've done it with a pair of 160 watt Mirage amps on 2-meters. Many years ago I owned one of the first high power (bout 600W) solid state 2-meter amps. Inside it was just several amps in parallel on the same, large circuit board. Capacitance on the input adjusted the phase and you basically tuned it for max. The output was the same way. However it used the earlier bi-polar transistors (this would have been in the late 70's) and there was quite a bit of interaction between input and output. I picked up a pair of 160 watt Mirage amps off e-Bay. With the Mirage amps I disabled the internal keying on one and set it up as a slave to the other. If you leave the internal keying on in both they will cycle back and forth which will have some rather undesirable effects. I used a C3i power divider/combiner on the input and another on the outputs. I tuned them up pretty much as I did the old amp and ended up with over 300 W out. This approach really need amps of the same make, model, and age (no design changes) to work the best but it will work. OTOH if starting >from new it's no more expensive to go out and purchase one of the new 380 watt TE amps. The high power Mirage is a bit more expensive. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com > >I split the output from my radio, lag one 90 degrees, put one in one yagi, >put one in another yagi and get circular polarization. > > >sc Article: 224703 of rec.radio.amateur.antenna From: "AAA RF Products" Subject: FS: UG-58A/U Type N Panel Mount Message-ID: Date: Wed, 24 May 2006 11:57:44 -0700 UG-58A/U Type N Panel Mount Connector made in USA. One piece solid nickel plated brass body. Captive silver plated contact, teflon insulation. Unlimited quantity availabe from stock. 1 to 99 ------ $2.95 each 100 to 499----$2.75 each 500+----------$2.50 each New Catalog Available Please email sales@AAARFProducts.com or call 949 481 3154 (San Clemente, CA, USA) Article: 224704 of rec.radio.amateur.antenna From: Roger Subject: Re: ARS License Numbers Message-ID: References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> Date: Wed, 24 May 2006 14:59:02 -0400 On Sun, 21 May 2006 19:30:37 -0400, "Lloyd" wrote: >Which "Roger" are you? The K8RI Roger. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com > > > >"Roger" wrote in message >news:g3t172tmmb8t25sbiu6h38h2sqvbefua9c@4ax.com... >> On Sat, 20 May 2006 15:15:39 -0700, "Sal M. Onella" >> wrote: Article: 224705 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Wed, 24 May 2006 12:11:52 -0700 Message-ID: <1279bvtn7e0p886@corp.supernews.com> References: <1276uslo9amil26@corp.supernews.com> <21360-4473893B-1884@storefull-3257.bay.webtv.net> <127739l4kf0e73a@corp.supernews.com> Richard Clark wrote: > . . . > Richard's applications and illustrations do not push this boundary. In > fact, Ramo et. al distinctly offer the case of "electrostatic > shielding" and clearly support the separation of magnetic and electric > flux (fields). . . Can you direct me to where in the text they do so? All I've found is a short section (5.28) on "Electrostatic Shielding" where they explain that introducing a grounded conductor near two others will reduce the capacitive coupling between them. Obviously this will alter the local E/H ratio, but in no way does it allow an E or H field to exist independently, even locally, let alone at any distance. Roy Lewallen, W7EL Article: 224706 of rec.radio.amateur.antenna From: Roger Subject: Re: ARS License Numbers Message-ID: References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> <1148279770.237761.281080@i40g2000cwc.googlegroups.com> Date: Wed, 24 May 2006 15:12:55 -0400 On 21 May 2006 23:36:10 -0700, nm5k@wt.net wrote: >>I asked around and found this practice is far from rare; I'm not sure >>"common" is the right word, though. > >You really need to type if you run cw over about 60wpm There aren't many who can type 60 wpm, but then again, maybe most of them are on high speed CW. <:-)) >or so.. That was about my limit as far as sending fairly clean >with a paddle. I never liked to type, so 55-60 wpm pretty much was I "touch type" and back when I was a grad student could type a bit over 60. Now days I have to make too many corrections to maintain that. >the limit for me. Most all the high speed people used a keyboard >to send. But I'd say the majority listened with their ears instead >of using a reader. The brain is a better reader than most puter CW Once you reach the point of copying subconsciously it's just like talking. >programs. Most don't handle noise very well. Once I hit 55-60 wpm >on a paddle, I was stretching the limits. Past that, and it was pretty I made 40 but never higher than that. OTOH back then I was spending one to two hours a day on CW. >dang ugly... Slopsville. The keyboards could kick back and type >about any CW speed with perfect sending. A decent typist can go >over 100 wpm+. There are few people who can type that fast. However on CW you type your response while listening to the other station so the transmission speed can be well above your typing speed. I can count on the fingers of one hand the number of people I've met in school and industry who could even approach that 100 wpm. The old electric portables used to jam the keys at much over 60 while the "selectric" could go a fair amount faster. When in college my daughter wore out one of those and she could out type it. I shouldn't count the college classes when I was a GA teaching the intro to CS, out of 195 students I only had about 10 that could type and none that could keep up with me. Unfortunately, age is catching up and I've had to slow down with the keyer and I'm not nearly as fast with the keyboard as I was. I can probably still type at 40 wpm after mistakes are taken out. 60 if I don't go back and correct. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com >MK Article: 224707 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <15322-44748CC5-24@storefull-3251.bay.webtv.net> Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Message-ID: <8X2dg.249$LO3.138@fe11.lga> Date: Wed, 24 May 2006 15:59:28 -0400 There is another potential problem if feeding two amps to two antennas that are reasonably close: RF from one antenna is induced into the other antenna, gets fed into the amp and causes some interference (mixing ?) that shows up as a raspy signal. Tried it, and heard it on another station attempting the same setup. It seems that it would be easier to control the phasing at the input of the PAs, but the above effect messes it up, unless antennas are widely separated and they do not "feed" each other setup. So, it appears that it is better to use one bigger amp and use proper phasing to feed the two or more antennas. -- Yuri Blanarovich, K3BU, VE3BMV Article: 224708 of rec.radio.amateur.antenna From: "Steve N." Subject: Re: Explanation wanted Date: Wed, 24 May 2006 15:18:16 -0500 Message-ID: References: "John, N9JG" wrote in message news:nvmdncAiGsLfgO7ZRVn-sQ@insightbb.com... > The ARRL Product Catalog at the link > http://www.arrl.org/catalog/?item=7571#top > lists a book titled "Stealth Amateur Radio", ... > > Since there appears to be a demand for this book, why wouldn't the ARRL rush > to get this book reprinted and posted for sale? John, Is this not obvious? Ask the ARRL. Speculations are easy. BTW, is this book any good? Dunno. 73, Steve, K9DCI Article: 224709 of rec.radio.amateur.antenna From: "Steve N." Subject: Re: Grounding a metal roof Date: Wed, 24 May 2006 15:48:25 -0500 Message-ID: References: <1148272981_5573@sp6iad.superfeed.net> "Richard Clark" wrote in message news:bkg2725ui18t5pct6cm4of8ejvhmoo21vf@4ax.com... > On Sun, 21 May 2006 23:48:59 -0500, "AG4QC" > wrote: > > >I am having a metal roof put on the house and shop. The installer said it > >isn't required to be grounded. The city inspector said the same thing. Is > >that really true? I'm thinking of running a #8 from the roof to my common > >ground. Does that make sense? > > Hi Joe, > > It is arguable that the entire roof would even be evenly conducting, > as installed. As conductivity is not a primary concern, the installer > is not motivated to insure that a #8 wire attached to one panel would > be felt by any other with any degree of confidence. Further, even if > all panels exhibited continuity today, this is not to say they would > tomorrow unless some care was taken to insure tight interconnections. > > It is not unheard of here in this group to find Hams taking that care > and bonding all panels. The sense of it is to reduce the chance of > developing spurs due to RF currents meeting corroded joints (although, > no one has ever reported this as a problem, only anticipated it). > > 73's > Richard Clark, KB7QHC Joe, Another concern (though I have no experience with roofs, just autos) is the intermitent contact (as opposed to a rectifying junction, as Richard points out) that is possible. If there are joints that can make and break, say in the wind, you may have noise generated. Chain-link fences would be susceptable to this as well. Wether or not it produces noise in your receiver, I would think, is rather unlikely, unless you were somewhere near a broadcast station or another ham for reasons described next. Interestingly enough, if the transmit antenna is reasonably close to the roof, it would manifest itself as noise on your *transmitted* signal also, but probably low enough such that those listeming to you would hear it. I had some experience with this phenomenon with things like trunk lids and motorcycle seat springs causing noise in the 150 MHz car phones of the past. The transmitter illuminated the noisy joint and the czarrier was literally modulated by this. The near-by noisy joint can be considered to be a parasitic element in the transmit antenna system and therefore produce low-level, but annoying amounts of noise modulation. It appears as sidebands on the transmitter which duplicate the noise of the joint. This in turn was wide-band exnogh to extend over to the receive frequency. Because it was full duplex and both Tx and Rx were on the same antenna, it was a noise problem in the receiver. Also why I believe it is a bad idea to use a chain link fence as a counterpoise. 73, Steve, K9DCI Article: 224710 of rec.radio.amateur.antenna From: "H. Adam Stevens, NQ5H" Subject: Re: Yacht Rf ground and radials Date: Wed, 24 May 2006 16:42:41 -0500 Message-ID: <1279kqsbib5oj71@corp.supernews.com> References: <447311d0_1@news.iprimus.com.au> http://www.photolib.noaa.gov/nurp/nur09010.htm This photo is of the barge over the Tektite II habitat; Summer 1970. I operated W2YRQ from inside the habitat with a Hy Gain 14 AVQ attached to this steel barge. We also dropped some heavy cable in the water with the conductors unwound. Worked great. 73 H. NQ5H PS Reg is usually right. "Reg Edwards" wrote in message news:HfudnZtD2umhrO7ZRVnyhA@bt.com... >A 6" square plate makes an adequate ground when immersed in salt sea > water. That is unless the transmitter power exceeds 10 kW. > > Article: 224711 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: FIGHT! FIGHT! FIGHT! Date: Wed, 24 May 2006 16:51:16 -0500 Message-ID: <20320-4474D554-26@storefull-3258.bay.webtv.net> References: Richard Clark wrote: "Your explanation sounds like you are practicing psychaitry, not technoligy." I think quantification is valuable if the measured value is accurate and if the value makes a difference. Antennas are used with transmitters of megawatts of power. These have limitations by regulations on maximum noise and harmonic content. It depends on the jurisdiction, but maximum noise and distortion must be at least 50 dB below the fully modulated level in some locales. I`ve often used the H.P. noise and distortion analyzer to measure off the air to be sure we complied with the regulation. It never occurred to me that our antenna system had a part in noise and distortion production. I expected curvature in a tube`s characteristics or a failed component to cause a rise in noise and distortion. Not once do I recall our antenna system causing distortion anywhere except in the edges of pattern nulls.=A0This is normal. Receiving antennas on the other hand deliver a satisfactory signal having only microwatts of power. As one responder noted the dynamic range is enormous. This is not really an issue for concern among amateurs. Antennas are in general distortion free. Best regards, RIchard Harrison, KB5WZI Article: 224712 of rec.radio.amateur.antenna From: ml Subject: tnx Re: sgc dipole? References: Message-ID: Date: Wed, 24 May 2006 22:55:34 GMT > -- just wanted to thank every for the help Article: 224713 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: <1148272981_5573@sp6iad.superfeed.net> Subject: Re: Grounding a metal roof Message-ID: Date: Wed, 24 May 2006 18:59:58 -0400 "Steve N." wrote in message news:e52gqp$tuu$1@avnika.corp.mot.com... > > "Richard Clark" wrote in message > news:bkg2725ui18t5pct6cm4of8ejvhmoo21vf@4ax.com... >> On Sun, 21 May 2006 23:48:59 -0500, "AG4QC" >> wrote: >> >> >I am having a metal roof put on the house and shop. The installer said >> >it >> >isn't required to be grounded. The city inspector said the same thing. >> >Is >> >that really true? I'm thinking of running a #8 from the roof to my >> >common >> >ground. Does that make sense? >> >> Hi Joe, >> >> It is arguable that the entire roof would even be evenly conducting, >> as installed. As conductivity is not a primary concern, the installer >> is not motivated to insure that a #8 wire attached to one panel would >> be felt by any other with any degree of confidence. Further, even if >> all panels exhibited continuity today, this is not to say they would >> tomorrow unless some care was taken to insure tight interconnections. >> >> It is not unheard of here in this group to find Hams taking that care >> and bonding all panels. The sense of it is to reduce the chance of >> developing spurs due to RF currents meeting corroded joints (although, >> no one has ever reported this as a problem, only anticipated it). >> >> 73's >> Richard Clark, KB7QHC > > Joe, > Another concern (though I have no experience with roofs, just autos) is > the > intermitent contact (as opposed to a rectifying junction, as Richard > points > out) that is possible. If there are joints that can make and break, say > in > the wind, you may have noise generated. Chain-link fences would be > susceptable to this as well. Wether or not it produces noise in your > receiver, I would think, is rather unlikely, unless you were somewhere > near > a broadcast station or another ham for reasons described next. > Interestingly enough, if the transmit antenna is reasonably close to > the > roof, it would manifest itself as noise on your *transmitted* signal also, > but probably low enough such that those listeming to you would hear it. > I had some experience with this phenomenon with things like trunk lids and > motorcycle seat springs causing noise in the 150 MHz car phones of the > past. > The transmitter illuminated the noisy joint and the czarrier was literally > modulated by this. The near-by noisy joint can be considered to be a > parasitic element in the transmit antenna system and therefore produce > low-level, but annoying amounts of noise modulation. It appears as > sidebands on the transmitter which duplicate the noise of the joint. This > in turn was wide-band exnogh to extend over to the receive frequency. > Because it was full duplex and both Tx and Rx were on the same antenna, it > was a noise problem in the receiver. Also why I believe it is a bad idea > to use a chain link fence as a counterpoise. > > 73, Steve, K9DCI > > Perhaps a more realistic concern would be lightning protection. A friend down in Fl had just installed a metal roof on his shop just 3 days prior to it being struck by lightning. Seems the worst damage was a softball size hole burned in the metal. First installing lightning rods and associated grounds would provide a good begining to bonding of a metal roof. Article: 224714 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: FIGHT! FIGHT! FIGHT! References: <20320-4474D554-26@storefull-3258.bay.webtv.net> Message-ID: <5R5dg.14811$fb2.5221@newssvr27.news.prodigy.net> Date: Wed, 24 May 2006 23:18:25 GMT Richard Clark wrote: > Cecil would shrug off 59% worth of distortion to define it linear. Richard, seems you suffer from the same affliction as Howard Hughes, repeating the same psychotic nonsense over and over. -- 73, Cecil http://www.qsl.net/w5dxp Article: 224715 of rec.radio.amateur.antenna Date: Wed, 24 May 2006 20:29:28 -0500 From: Tom Ring Subject: Re: ARS License Numbers References: <1148005814.174874.234520@38g2000cwa.googlegroups.com> <446e70b0$0$1010$39cecf19@news.twtelecom.net> <1148088937.210792.29680@38g2000cwa.googlegroups.com> <1148279770.237761.281080@i40g2000cwc.googlegroups.com> Message-ID: <44750879$0$6150$39cecf19@news.twtelecom.net> Roger wrote: > There are few people who can type that fast. However on CW you type > your response while listening to the other station so the transmission > speed can be well above your typing speed. > > I can count on the fingers of one hand the number of people I've met > in school and industry who could even approach that 100 wpm. > The old electric portables used to jam the keys at much over 60 while > the "selectric" could go a fair amount faster. When in college my > daughter wore out one of those and she could out type it. My father was NY state champ at over 100 wpm on a manual typewriter in about 1940. I always figured Bucky the milkman must have been my real father, since I was at 15 wpm before typing class, and 12 after a year of it. I still type with 4 fingers, and have to use my eyes to figure where they should go. And I have typed for a living for the last 30+ years. :) tom K0TAR Article: 224716 of rec.radio.amateur.antenna Date: Wed, 24 May 2006 21:12:10 -0500 From: Tom Ring Subject: Re: What happens if you pipe the output of one radio in to 2 amps? References: <15322-44748CC5-24@storefull-3251.bay.webtv.net> <8X2dg.249$LO3.138@fe11.lga> Message-ID: <4475127b$0$1010$39cecf19@news.twtelecom.net> Yuri Blanarovich wrote: > There is another potential problem if feeding two amps to two antennas that > are reasonably close: RF from one antenna is induced into the other antenna, > gets fed into the amp and causes some interference (mixing ?) that shows up > as a raspy signal. > Tried it, and heard it on another station attempting the same setup. > It seems that it would be easier to control the phasing at the input of the > PAs, but the above effect messes it up, unless antennas are widely separated > and they do not "feed" each other setup. > So, it appears that it is better to use one bigger amp and use proper > phasing to feed the two or more antennas. > Well, the expert, or should I say, the new GURU, has spoken. He seems to know all about this complex subject. I know I will never try this again, as my previous efforts, which seemed to work, could not possibly have done so. Obviously Wilkenson hybrids are useless, likewise any ring hybrids, and all other methods of splitting/combining a transmitter feed. Sorry guys, they won't work. Yuri said so. tom K0TAR Article: 224717 of rec.radio.amateur.antenna From: "Jerry Martes" References: <6hAcg.5443$oa3.1513@trnddc08> <1148483679.078024.19470@i40g2000cwc.googlegroups.com> <1148490568.117358.31110@y43g2000cwc.googlegroups.com> Subject: Re: Question about the uses for an antenna design Message-ID: Date: Thu, 25 May 2006 02:39:39 GMT wrote in message news:1148490568.117358.31110@y43g2000cwc.googlegroups.com... > Are the differences physical, electrical or both? > > I must be picturing the wrong setup if I'm conflating your design with > the Lindendblad. > > You've mentioned the 137MHz Wefax antenna, and that one's not a > concept... can you pass along some construction details so I can get a > clear picture of it? > > Dan Hi Dan Yeah, I can show you exactly how I built a Double Cross for receiving NOAA satellite signals. A buddy of mine has chosen to publish everything I send him. http://213.250.83.83/~jerry/index.html There is probably too much data on that site. The excess info and pictures may get confusing. Since you read this "antennas group", I'll assume that you may know as much or more about antennas as I do. I dont claim to know *the best* configuration of the Cross concept for APT reception. I do suggest that four dipoles mounted so they are tilted slightly from vertical and spaced so the diagonal dipoles are about 1/6th wave separated. can be easily fed to provide RHCP toward the horizon and toward zenith. In the web site http://www.amsat.org/amsat/articles/w6shp/lindy.html The Lindenblad is described as an array of four dipoles tilted 30 degrees >from Horizontal and spaced 0.3 wave and all fed in phase. The Lindenblad has a deep null straight up. The Double Cross has no null anywhere in the hemisphere. Thanks for the interest in the Cross. If you have any situation where this hemispheric coverage with sensitivity to circular polarization, I'd be interested in helping you design a Double Cross. All the Double Cross antennas I've made seem to work well for receiving signals from the NOAA polar orbiting satellites. Jerry Article: 224718 of rec.radio.amateur.antenna From: Buck Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Message-ID: <4k7a7253kkr6qr7juk3a7ckthqgo54r070@4ax.com> References: <15322-44748CC5-24@storefull-3251.bay.webtv.net> <8X2dg.249$LO3.138@fe11.lga> Date: Wed, 24 May 2006 23:18:07 -0400 On Wed, 24 May 2006 15:59:28 -0400, "Yuri Blanarovich" wrote: >There is another potential problem if feeding two amps to two antennas that >are reasonably close: RF from one antenna is induced into the other antenna, >gets fed into the amp and causes some interference (mixing ?) that shows up >as a raspy signal. >Tried it, and heard it on another station attempting the same setup. >It seems that it would be easier to control the phasing at the input of the >PAs, but the above effect messes it up, unless antennas are widely separated >and they do not "feed" each other setup. >So, it appears that it is better to use one bigger amp and use proper >phasing to feed the two or more antennas. OK, this brings up another thought... Would the transmitted signal >from antenna a, being close to b, cause b to have a high swr and vica versa? -- 73 for now Buck N4PGW Article: 224719 of rec.radio.amateur.antenna From: "U-Know-Who" References: <1148333653.989066.182600@38g2000cwa.googlegroups.com> <1148333799.022539.52100@j33g2000cwa.googlegroups.com> <1148410520.479296.296360@j73g2000cwa.googlegroups.com> <1148513694.742031.233820@38g2000cwa.googlegroups.com> Subject: What radio equipment do you own Markie? Message-ID: <7m9dg.58262$Qq.45028@tornado.texas.rr.com> Date: Thu, 25 May 2006 03:18:27 GMT "an_old_friend" wrote in message news:1148513694.742031.233820@38g2000cwa.googlegroups.com... > > Howard W3CQH wrote: >> Why don't you take this CRAP off line to your friends - it doesn't belong >> in >> any of the HAM RADIO newsgroups! >> > becuase he is too much of a cowardly child to do so > > I thank you sir for puting the blamewhere it belongs on the posters of > such crap > > for my part Id be glad not to discuss such a subject in any radio NG if > the rest of the NG would only do the same > Read the subject, put your money where your mouth is. Article: 224720 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <20320-4474D554-26@storefull-3258.bay.webtv.net> Subject: Re: FIGHT! FIGHT! FIGHT! Message-ID: Date: Wed, 24 May 2006 20:50:17 -0700 "Richard Harrison" wrote in message news:20320-4474D554-26@storefull-3258.bay.webtv.net... < snip > Antennas are in general distortion free. Yes, but "bad times" can make them non-linear. Consider the bolted joints that get corroded and semi-conductive over time, with rain and temperature changes to help. Nearby RF sources can generate distortion products in my antennas if I haven't kept up my maintenance. Article: 224721 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1148272981_5573@sp6iad.superfeed.net> Subject: Re: Grounding a metal roof Message-ID: Date: Wed, 24 May 2006 21:13:29 -0700 "Steve N." wrote in message news:e52gqp$tuu$1@avnika.corp.mot.com... < snip > > Another concern (though I have no experience with roofs, just autos) is the > intermitent contact (as opposed to a rectifying junction, as Richard points > out) that is possible. If there are joints that can make and break, say in > the wind, you may have noise generated. Chain-link fences would be > susceptable to this as well. Wether or not it produces noise in your > receiver, I would think, is rather unlikely, unless you were somewhere near > a broadcast station or another ham for reasons described next. It's mostly a problem if you are running two or more rigs at the same time. Your 2M packet rig could interfere with your 2M ragchew. The Navy, for whom I work, bonds (or isolates) everything topside for exactly the reason you stated. The intermittent contacts are noise generators. The tools for detecting some troublesome items are a rubber mallet and a pair of handhelds. One guy in radio transmits a carrier, while listening on a nearby freq. If he hears anything, he grabs his handheld and barks, "What was that you just tapped on?" Primitive but functional. Every spark, no matter how small, is an RF generator. Chains are awful. We hate chains. Article: 224722 of rec.radio.amateur.antenna From: "laborkei" Subject: ebay: Icom 756 PROII Available, Nice ! Message-ID: <1Cfdg.46071$QU3.35310@bignews8.bellsouth.net> Date: Thu, 25 May 2006 06:25:21 -0400 http://cgi.ebay.com/Icom-756PROII-Transceiver_W0QQitemZ9731654891 -- Article: 224723 of rec.radio.amateur.antenna From: Buck Subject: Re: ebay: Icom 756 PROII Available, Nice ! Message-ID: <7f6b729kr9vm6o3amk40ldk74c2m8b11ho@4ax.com> References: <1Cfdg.46071$QU3.35310@bignews8.bellsouth.net> <1148552986.398194.197110@38g2000cwa.googlegroups.com> Date: Thu, 25 May 2006 07:51:40 -0400 On 25 May 2006 03:29:46 -0700, w8ji@akorn.net wrote: >laborkei wrote: >> http://cgi.ebay.com/Icom-756PROII-Transceiver_W0QQitemZ9731654891 > >Why would anyone spam an antenna discussion reflector with ebay trash? They are too dumb to realize that the ebay search will bring up the item to those who are interested in finding it. -- 73 for now Buck N4PGW Article: 224724 of rec.radio.amateur.antenna From: Buck Subject: Re: ebay: Icom 756 PROII Available, Nice ! Message-ID: <4n6b72davtbs84eapatpkoetbp45irjntg@4ax.com> References: <1Cfdg.46071$QU3.35310@bignews8.bellsouth.net> Date: Thu, 25 May 2006 07:57:25 -0400 On Thu, 25 May 2006 06:25:21 -0400, "laborkei" wrote: >http://cgi.ebay.com/Icom-756PROII-Transceiver_W0QQitemZ9731654891 abuse@bellsouth.net -- 73 for now Buck N4PGW Article: 224725 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <15322-44748CC5-24@storefull-3251.bay.webtv.net> <8X2dg.249$LO3.138@fe11.lga> <4475127b$0$1010$39cecf19@news.twtelecom.net> Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Message-ID: Date: Thu, 25 May 2006 11:13:52 -0400 "Tom Ring" wrote in message news:4475127b$0$1010$39cecf19@news.twtelecom.net... > Yuri Blanarovich wrote: > >> There is another potential problem if feeding two amps to two antennas >> that are reasonably close: RF from one antenna is induced into the other >> antenna, gets fed into the amp and causes some interference (mixing ?) >> that shows up as a raspy signal. >> Tried it, and heard it on another station attempting the same setup. >> It seems that it would be easier to control the phasing at the input of >> the PAs, but the above effect messes it up, unless antennas are widely >> separated and they do not "feed" each other setup. >> So, it appears that it is better to use one bigger amp and use proper >> phasing to feed the two or more antennas. >> > > Well, the expert, or should I say, the new GURU, has spoken. He seems to > know all about this complex subject. > Aaaah, here chimes in another W8JI worshipper, who can not read posting, understand it and reply intelligently, but resorting to snotty, personal, pathetic remarks. You may have noticed that I do not take crap and respond in kind. > I know I will never try this again, as my previous efforts, which seemed > to work, could not possibly have done so. Obviously Wilkenson hybrids are > useless, likewise any ring hybrids, and all other methods of > splitting/combining a transmitter feed. > READ IT AGAIN carefully, I have not say that "Wilkenson" (learn spelling) hybrid would not work or anything about dividing - combining signals. I have noted that if TWO amplifiers are fed into TWO (separate) antennas that are in close proximity (mutual impedance at play) then the signals from the one antenna get picked up by the other antenna, fed back to the amplifiers and cause distortion that manifests itself as a raspy CW tone or SSB modulation on the air. I also mentioned that possible remedy is to separate the antennas in a such way that there is no significant signal feedback between them. Like you could have one amp feeding EU antenna, and another one feeding SA antenna, separated properly, fed from the same TX and using splitters, to satisfy the impedance match between the TX and AMPS. > Sorry guys, they won't work. Yuri said so. > I didn't say such a thing, I brought up potential problem to situation (feeding 2 amps to 2 ants) in question and offered possible solution. I did not even mention hybrids or ways of phasing the gizmos, where did you get it from, private conversation with the other Tom? You got the GURU thing mixed up. I do not play GURU on Internet by publicizing "wisdom pages" like W8JI does, I would chime in with help when I see the need for it (and have time) or when I see gross crap being paraded as "gospel". Thank you for showing your feathers and displaying your depth! Your picture would look pretier if you engaged in technical, civil discussions, rather than that "W8JI thing". > tom > K0TAR > Yuri Blanarovich, K3BU, VE3BMV etc. Article: 224726 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: FIGHT? Here is another W8JI myth bone! Date: Thu, 25 May 2006 08:40:26 -0700 Message-ID: <127bjves1rp06fa@corp.supernews.com> References: <1276uslo9amil26@corp.supernews.com> <21360-4473893B-1884@storefull-3257.bay.webtv.net> <127739l4kf0e73a@corp.supernews.com> <1279bvtn7e0p886@corp.supernews.com> <7cd972lnqpn8ir6p97q3ajb9f87nf0bv0a@4ax.com> <1148517119.544876.272330@j33g2000cwa.googlegroups.com> <1148553494.112985.49700@j73g2000cwa.googlegroups.com> <87jb72lnlmra471luaon4p3us57g42f1o0@4ax.com> Richard Clark wrote: > On 25 May 2006 03:38:14 -0700, w8ji@akorn.net wrote: > >>> There are too many contra-examples too sustain your point. What you >>> are talking about is radiation, this does not account for common >>> induction that occurs on the very short scales I've offered. >> Will you give me an example where the electric field is zero and all >> coupling is via magnetic flux? > > Tom, > > As this has already been discussed not but two postings ago, the > posting your responded to, why are you asking for that content again? I was going to ask the same question but Tom beat me to it. And I must have missed the example, too. Would you be so kind as to repost it? Roy Lewallen, W7EL Article: 224727 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1276uslo9amil26@corp.supernews.com> <21360-4473893B-1884@storefull-3257.bay.webtv.net> <127739l4kf0e73a@corp.supernews.com> <1279bvtn7e0p886@corp.supernews.com> <7cd972lnqpn8ir6p97q3ajb9f87nf0bv0a@4ax.com> <1148517119.544876.272330@j33g2000cwa.googlegroups.com> <1148553494.112985.49700@j73g2000cwa.googlegroups.com> <87jb72lnlmra471luaon4p3us57g42f1o0@4ax.com> <127bjves1rp06fa@corp.supernews.com> Subject: Re: FIGHT? Here is another W8JI myth bone! Message-ID: Date: Thu, 25 May 2006 16:09:52 GMT "Roy Lewallen" wrote: > I was going to ask the same question but Tom beat me to it. And I must > have missed the example, too. Would you be so kind as to repost it? Not sure of the context but ideally at a voltage node in an unterminated transmission line, the E-field is very close to zero while almost all of the EM energy exists in the H-field. According to "Optics", by Hecht, the same thing can happen in free space with light waves. -- 73, Cecil, W5DXP Article: 224728 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <15322-44748CC5-24@storefull-3251.bay.webtv.net> <8X2dg.249$LO3.138@fe11.lga> <4475127b$0$1010$39cecf19@news.twtelecom.net> Subject: Re: What happens if you pipe the output of one radio in to 2 amps? Message-ID: Date: Thu, 25 May 2006 12:26:32 -0400 "Richard Clark" wrote in message news:sujb72974rd97dpq24jdacl17e7pag7e0o@4ax.com... > On Thu, 25 May 2006 11:13:52 -0400, "Yuri Blanarovich" > wrote: > >> I do not play GURU on Internet by publicizing "wisdom pages" like W8JI >>does > > Hi Yuri, > > http://www.k3bu.us/loadingcoils.htm > Looks like one of those GURU wisdom pages. A break-away from the Rome > church of QSL.NET. You even have publicized a new link to devotional > writings from your worshippers. They have all the steamy revelation > as the "Gospel of Judas Iscariot" just discovered. > > 73's > Richard Clark, KB7QHC > whose meek acolytes only whisper their prayers to him privately. Not at all sireee! This was response to W8JI baloney and to provide place for some explanation and graphics, which reflectors and NGs do not afford. If you followed my publishing career since 1958 and behind the Iron Curtain, and if you knew me, you would find that I keep most of the stuff to myself, even some groundbreaking ideas or inventions, I use them to my advantage to gear up and operate in the contests, where I enjoy beating the competition, there, stripped of pompous drivel and boasting. There, results are expressed as points, placement in the ladder or record tables. It is the most misleading junk science, that when I see it, I get stirred up enough to respond with what I know to be the right or backed up by reality. So if you look at my web site and see the "coil thing" and comparing this to W8JI "guru thing" I wonder about your judgement. I am trying to be civil and stay with technical discussions, but if someone resorts to personal attacks and crap, I do not take it laying down with my mouth open. I think you would be better off also to stick to matter o'fact technical discussions rather than trying to display your literary talents of poking people in the eyes. I could care less what youze guyze here theoretize about or fight for number one wize guy on the totem pole, or who you worship. I enjoy ham radio as a means to keep in step with technology, enjoy contacting and beating people in the contests and to keep my mind sharp. Last thing I "enjoy" is arguing with an idiot or participate in a pissing contests with skunks. I hope I 'splained myself poetically enuf! So I will not try to be the "last one standing - right" as W8JI philosophy is. You can have it - argue all you want. I posted what I know, have seen, am convinced of and can prove it. You can "figure" it all you want. I said, described my piece, the reality is the judge and not some scientwists! Have nice Memorial Day, remember those who gave their lives so you can live in a freedom, otherwise sucks! Been there, paid with lives of dear ones! 73 -- Yuri Blanarovich, K3BU, VE3BMV Article: 224729 of rec.radio.amateur.antenna From: "Bill Ogden" Subject: Ramsey ferrite rod antenna Message-ID: Date: Thu, 25 May 2006 13:59:12 -0400 Has anyone tried the Ramsey "Signal Magnet Antenna" as a 160 or 80 meter antenna? It is a ferrite rod (looks about 8 inches long) with a preamp installed next to the rod. The rod would be installed remotely from the control box, using an RG59 connection. It was designed for broadcast band use, but can be tuned elsewhere. ---- BTW, is there a known problem with the eham site? Bill - W2WO Article: 224730 of rec.radio.amateur.antenna Subject: Re: Ramsey ferrite rod antenna From: Ed References: Message-ID: Date: 25 May 2006 17:42:41 GMT > > BTW, is there a known problem with the eham site? > > Bill - W2WO > > yes reported to be DNS issue, to be hopefully fixed today.