Article: 94341 of rec.radio.amateur.homebrew From: sdeyoreo@hotmail.com Subject: Re: Use microwave oven chassis for a radio? Message-ID: References: Date: Tue, 13 Sep 2005 20:20:57 -0400 On 12 Sep 2005 23:01:40 -0500, mcalhoun@ksu.edu wrote: >I recently tore another microwave oven apart for the two really-strong >magnets that are in the tube > > (they are fun to stack alternate-polarity on a wooden dowel > so they seem to "float" in the air; kids of all ages just > love to play that that "toy") > >(I kept the transformer, diode, capacitor, and misc. microswitches, too), > >and as I carried the rather bare chassis out to the garbage-can area, >I wondered if anyone had ever tried built an amplifier in such a chassis >-- maybe even using some of its many interlocks? No, but the tube runs at a freq real close to ham Slow Scan TV bands. They retune them and use them as SSTV transmitters. Article: 94342 of rec.radio.amateur.homebrew From: Gregg Subject: Re: Big old-fashioned IF transformers for tube-type homebrewing? Date: Tue, 13 Sep 2005 17:50:23 -0700 References: <1126653515.795787.34880@g43g2000cwa.googlegroups.com> Message-ID: <432773c1$1_1@dowco.com> Behold, Tim Shoppa scribed on tube chassis: > Are the big old-fashioned IF transformers-in-a-can available anywhere > anymore? I want to make a receiver, probably double conversion, which > would mean that I'd want several each of the 50kHz and some higher > frequency (455kHz likely). > > Are these things that can be made from scratch without a lot of > difficutly? I can wind coils etc. but don't have any transformer > slug-tuned cores. > > Tim KA0BTD Hi Tim, Check out my article here: http://geek.scorpiorising.ca/455KHz.html Cheers! -- Gregg "t3h g33k" http://geek.scorpiorising.ca *Ratings are for transistors, tubes have guidelines* Article: 94343 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Big old-fashioned IF transformers for tube-type homebrewing? Message-ID: <4ouei1p7no2gchbhdrscbllq8hvt3ocf6n@4ax.com> References: <1126653515.795787.34880@g43g2000cwa.googlegroups.com> Date: Wed, 14 Sep 2005 01:34:37 GMT On 13 Sep 2005 17:08:48 -0700, "Tim Shoppa" wrote: >Are the big old-fashioned IF transformers-in-a-can available >anywhere anymore? I want to make a receiver, probably double >conversion, >which would mean that I'd want several each of the 50kHz and some >higher frequency (455kHz likely). > >Are these things that can be made from scratch without a lot of >difficutly? I can wind coils etc. but don't >have any transformer slug-tuned cores. > >Tim KA0BTD Hi Tim, They are homebrewable. I needed a few 455khz for a tube RX I was building and basically resused some old "IF like" cans by replacing the guts with handwound coils and caps. The forms for the coils were Horz width coils from a few dead monitors, used the slugs too. Used one of the basic programs for solonoid coils to get a rough number of turns and then then wound 30% less in scramble form. That gave a basic coil and then resonated it with a cap to 500khz. Once the slug was added it easily tuned down to 400 so I cut the slug shorter (1/2) and it was fine for 455. The distance between the two coils (for double tuned IFs) determines the coupling factor, or more directly the selectivity and losses. Once you have the recipie for one winding you can easily reproduce it. Theres nothing special about IF cans save for they have to tune the desired range, have a decent Q and are shielded. The outer can however is important or that IF amp will become an IF osc. But even the can can be liberated from salvage or made from copper, tin or aluminum stock. I made some really nice looking cans using 1" Copper pipe and pipe caps, heavy but well shielded. Soda straw was the coil form and holes in the ends supported it and allowed access to tuning slugs. Leads came out using insulated Teflon feedthroughs. Looked very industrial. Allison KB1GMX Article: 94344 of rec.radio.amateur.homebrew From: "Joel" References: Subject: Re: Use microwave oven chassis for a radio? Date: Tue, 13 Sep 2005 20:52:33 -0500 Message-ID: Huh??? I would think you wouldn't need slow-scan TV in the microwave portion of the ham bands.. There is more then enough bandwidth available for many fast scan TV signals.. Or maybe I'm missing something.. Joe AG4QC wrote in message news:s4rei1to43u8jf9pqk9lvgjkdofkcfqk9e@4ax.com... > On 12 Sep 2005 23:01:40 -0500, mcalhoun@ksu.edu wrote: > >>I recently tore another microwave oven apart for the two really-strong >>magnets that are in the tube >> >> (they are fun to stack alternate-polarity on a wooden dowel >> so they seem to "float" in the air; kids of all ages just >> love to play that that "toy") >> >>(I kept the transformer, diode, capacitor, and misc. microswitches, too), >> >>and as I carried the rather bare chassis out to the garbage-can area, >>I wondered if anyone had ever tried built an amplifier in such a chassis >>-- maybe even using some of its many interlocks? > No, but the tube runs at a freq real close to ham Slow Scan TV bands. > They retune them and use them as SSTV transmitters. Article: 94345 of rec.radio.amateur.homebrew From: et472@FreeNet.Carleton.CA (Michael Black) Subject: Re: Use microwave oven chassis for a radio? Date: 14 Sep 2005 02:29:46 GMT Message-ID: References: "Joel" (Joel@cyberbest.com) writes: > Huh??? I would think you wouldn't need slow-scan TV in the microwave > portion of the ham bands.. There is more then enough bandwidth available for > many fast scan TV signals.. Or maybe I'm missing something.. > > Joe AG4QC It was a nonsense reply, though I couldn't decide whether he was trolling or actually didn't hav e a clue. Michael VE2BVW > wrote in message > news:s4rei1to43u8jf9pqk9lvgjkdofkcfqk9e@4ax.com... >> On 12 Sep 2005 23:01:40 -0500, mcalhoun@ksu.edu wrote: >> >>>I recently tore another microwave oven apart for the two really-strong >>>magnets that are in the tube >>> >>> (they are fun to stack alternate-polarity on a wooden dowel >>> so they seem to "float" in the air; kids of all ages just >>> love to play that that "toy") >>> >>>(I kept the transformer, diode, capacitor, and misc. microswitches, too), >>> >>>and as I carried the rather bare chassis out to the garbage-can area, >>>I wondered if anyone had ever tried built an amplifier in such a chassis >>>-- maybe even using some of its many interlocks? >> No, but the tube runs at a freq real close to ham Slow Scan TV bands. >> They retune them and use them as SSTV transmitters. > > Article: 94346 of rec.radio.amateur.homebrew From: kludge@panix.com (Scott Dorsey) Subject: Re: Big old-fashioned IF transformers for tube-type homebrewing? Date: 14 Sep 2005 01:05:29 -0400 Message-ID: References: <1126653585.459065.41060@g43g2000cwa.googlegroups.com> Tim Shoppa wrote: >Are the big old-fashioned IF transformers-in-a-can available >anywhere anymore? I want to make a receiver, probably double >conversion, >which would mean that I'd want several each of the 50kHz and some >higher frequency (455kHz likely). Try a hamfest, or Antique Electronics Supply. >Are these things that can be made from scratch without a lot of >difficutly? I can wind coils etc. but don't >have any transformer slug-tuned cores. They are a bloody pain. You should try it. If it was easy, it wouldn't be fun. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." Article: 94347 of rec.radio.amateur.homebrew From: Paul Keinanen Subject: Re: Butterworth bandpass filter question Message-ID: References: <1126570392.772936.313960@g47g2000cwa.googlegroups.com> <1126646519.766808.254200@f14g2000cwb.googlegroups.com> Date: Wed, 14 Sep 2005 09:17:20 +0300 On 13 Sep 2005 14:21:59 -0700, "K7ITM" wrote: >But even so, even if you DID have a broadband antenna, you can find op >amps, and you can make amplifiers with discrete parts, that have >distortion products more than 120dB below the level of signals in >excess of a volt at the amplifier output, in the LF frequency range. >In other words, the distortion products will be less than a microvolt, >with one volt output signals. You don't need to run that preamp with >any appreciable voltage gain, so you're handling some pretty big input >signals. With some kind of vertical antenna (possibly with some capacitance) which is small compared to the wavelength on LF, it is going to have a large capacitive reactance. There will also be some antenna input capacitance from input to ground, so essentially there is a capacitive voltage divider formed by the antenna capacitance and input capacitance and the amplifier is trying to tap off that voltage. So the amplifier really needs current gain, not voltage gain i.e. a high input impedance and a manageable (50 ohm etc.) output impedance. Paul OH3LWR Article: 94348 of rec.radio.amateur.homebrew From: "Markus L" References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> Subject: Re: switching power mosfet as RF amplifiers Message-ID: Date: Wed, 14 Sep 2005 09:14:26 +0200 "Jim" wrote in message news:QaKdncJLMoqYB7reRVn-pQ@comcast.com... > Most power MosFets have a large Gate to Source capacitance which makes it > difficult to use them at radio frequencies. > > It can be done, but the higher the desired operating frequency the > greater effect the parasitic capacitance has, so most designs I have seen > were up to 7 MHz and that was about the upper limit. A German ham radio magazine just published a project for a 400W MOSFET PA covering the 80...20m bands: http://www.vth.de/FUNK/funk/09_05/28.asp Markus HB9BRJ Article: 94349 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> <1dvdi1lqodbfnqvsvk7oh34vqgo8offr55@4ax.com> <1126686255.980443.67350@g49g2000cwa.googlegroups.com> Date: Wed, 14 Sep 2005 12:18:39 GMT On 14 Sep 2005 01:24:16 -0700, francesco.messineo@gmail.com wrote: > >nospam@nouce.bellatlantic.net ha scritto: > >> >> Good luck. Most of those devices will exhibit gain to amazing >> frequencies due the fact that fets have no real limits like junction >> transistors. What they do have that limits them is real world things >> like lead inductance, Input capacitance, output capacitance and Drain >> to Gate Miller capacitance all of which make it difficult to get power >> in and out of them as frequency increases. >> >> The input capacitance for the IRF510 is 135pf, the higher power parts >> can easily be upwards of 1275pf for the IFR640 (Xc of around 2ohms). >> Output capacitance around 400pf and feedback capacitance of 100PF >> also for the 640. > >Reading from the ARF488 datasheet (this mosfet is made for RF >amplification >up to 60 MHz or so) I see input capacitance of 1400 pf typical, and >150 pf output capacitance typical. >The IRF840 datasheet reports 1300 pf and 200 pf in/out capacitance >at the same frequency of the ARF488 (1 MHz). So what else affect >high frequency performance of these devices? Is the 50 pf difference >in output capacitance the "big" problem? Reverse transfer capacitance >of the ARF488 is 65 pf against the 18 pf of the IRF840. Yes that is true. However that input capacitance is close to what I'd use to bypass a 50mhz circuit. It's near RF dead short unless you try to absorb it into the feed network. Even then it's a very low Z. >> >> I have driven an IRF510 at 50mhz and gotten 4.5W out of it. To do so >> I had to drive it as a 5 to 10ohm very reactive input, use a 24V >> supply and load the output to around 10ohms, and bias it for 100ma >> minimum. It was unstable thermally(tended to runaway toward device >> burnout). The output spectrum (harmonics) and IMD were poor. >> At 12V power out was nearly RF power input. > >not so encouraging... All I can say it try the most likely candidate. They are designed for switching power at a few hundred KHZ. Best results will require a 24V or maybe a 40-50V power source. >> >> It was more effort than driving a 2SC1307 (old cb final) at 12V, more >> gain and the IMD was better. At 12V the 1306 gave 6W carrier power >> with good stability. A pair of 2sc1971 driven pushpull easily give >> 10-11W carrier at 12V and are fairly clean. >> >> There are FETs characterized for RF power but they are not inexpensive >> and corosponding bipolar devices are fairly cheap. > >what do you suggest on the bipolar side to obtain at least 100W CW >on 50 MHz? Monitor line output transistors are any good? >Thanks and 73 > >Francesco IS0FKQ MRF492 is a good 70w device I've had good success with. If you can afford it MRF141 RF power fets or MRF150 but they are expensive. There are a number of 2SCxxxx part numbers that also would fit the need but experience with them is limited. If all else failes a Valve such as a 4cx250 with 800-900V on the plate would do 100 or more watts out. Allison Article: 94350 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> Date: Wed, 14 Sep 2005 12:21:49 GMT On Tue, 13 Sep 2005 20:33:11 -0700, "Jim" wrote: > Most power MosFets have a large Gate to Source capacitance which makes it >difficult to use them at radio frequencies. > > It can be done, but the higher the desired operating frequency the >greater effect the parasitic capacitance has, so most designs I have seen >were up to 7 MHz and that was about the upper limit. > > > > Jim Pennell > N6BIU 7mhz was not the upper limit but around 20m the Gate Xc does makes them harder to drive. There are a number of designs that run them as linear amps to 10m but the drive networks take that into account. A pair of IRF510s will do 35-40W in the FARA design published in QST. Allison Article: 94351 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: <5g5gi15s5cosbuumc47imgeje5j3o0acvd@4ax.com> References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> Date: Wed, 14 Sep 2005 12:26:31 GMT On Wed, 14 Sep 2005 09:14:26 +0200, "Markus L" wrote: >"Jim" wrote in message >news:QaKdncJLMoqYB7reRVn-pQ@comcast.com... >> Most power MosFets have a large Gate to Source capacitance which makes >it >> difficult to use them at radio frequencies. >> >> It can be done, but the higher the desired operating frequency the >> greater effect the parasitic capacitance has, so most designs I have seen >> were up to 7 MHz and that was about the upper limit. > >A German ham radio magazine just published a project for a 400W MOSFET PA >covering the 80...20m bands: >http://www.vth.de/FUNK/funk/09_05/28.asp > >Markus HB9BRJ > Yes but were they class E or linear? There are a number of AM ops on 160/75/40m running 1kw AM phone using class E FET. However class E for 6M I havent seen yet. The german design would not run at 6m and thats what the initial posting asked for. Those power fets at lower frequencies are a very useful devices but at VHF their characteristics are difficult to accomodate. Allison Article: 94352 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> <1dvdi1lqodbfnqvsvk7oh34vqgo8offr55@4ax.com> <1126686255.980443.67350@g49g2000cwa.googlegroups.com> <1126705718.554738.27190@g44g2000cwa.googlegroups.com> Date: Wed, 14 Sep 2005 16:03:15 GMT On 14 Sep 2005 06:48:38 -0700, francesco.messineo@gmail.com wrote: > Hello, > > >nospam@nouce.bellatlantic.net ha scritto: > >> On 14 Sep 2005 01:24:16 -0700, francesco.messineo@gmail.com wrote: >> >> > >> >nospam@nouce.bellatlantic.net ha scritto: >> > >> >> >> >> Good luck. Most of those devices will exhibit gain to amazing >> >> frequencies due the fact that fets have no real limits like junction >> >> transistors. What they do have that limits them is real world things >> >> like lead inductance, Input capacitance, output capacitance and Drain >> >> to Gate Miller capacitance all of which make it difficult to get power >> >> in and out of them as frequency increases. >> >> >> >> The input capacitance for the IRF510 is 135pf, the higher power parts >> >> can easily be upwards of 1275pf for the IFR640 (Xc of around 2ohms). >> >> Output capacitance around 400pf and feedback capacitance of 100PF >> >> also for the 640. >> > >> >Reading from the ARF488 datasheet (this mosfet is made for RF >> >amplification >> >up to 60 MHz or so) I see input capacitance of 1400 pf typical, and >> >150 pf output capacitance typical. >> >The IRF840 datasheet reports 1300 pf and 200 pf in/out capacitance >> >at the same frequency of the ARF488 (1 MHz). So what else affect >> >high frequency performance of these devices? Is the 50 pf difference >> >in output capacitance the "big" problem? Reverse transfer capacitance >> >of the ARF488 is 65 pf against the 18 pf of the IRF840. >> >> Yes that is true. However that input capacitance is close to what I'd >> use to bypass a 50mhz circuit. It's near RF dead short unless you >> try to absorb it into the feed network. Even then it's a very low Z. > >Yes, I understand it. What isn't clear to me is why the ARF488 is >specified >for > 60 MHz and has input capacitance > of the one of an IRF840. >On QEX of may/jun 1999 you can find a 300W 50 MHz amplifier with >ARF488 push-pull. I'll check that one out. I do not have QEX back to '99 so it may take a while to get it. I suspect the ARF488 is a RF rated varient of the IRFs and may offer other characteristice that are more complient at VHF. I cannot find any data or even a reference to ARF488. I am a 6m op that love to play on that band so curiousity always wins. >> >> All I can say it try the most likely candidate. They are designed for >> switching power at a few hundred KHZ. >> >> Best results will require a 24V or maybe a 40-50V power source. > >no problem, I can even use 100V or more. > > >> > >> >what do you suggest on the bipolar side to obtain at least 100W CW >> >on 50 MHz? Monitor line output transistors are any good? >> >Thanks and 73 >> > > >> >> MRF492 is a good 70w device I've had good success with. If you can >> afford it MRF141 RF power fets or MRF150 but they are expensive. >> There are a number of 2SCxxxx part numbers that also would fit the >> need but experience with them is limited. >> >> If all else failes a Valve such as a 4cx250 with 800-900V on the plate >> would do 100 or more watts out. > >I should have a couple of 4cx150 around, but this amplifier should >sit right under the antenna in the same box with a receive >preamplifier. >I was trying to avoid a big tube ampli. And also I was trying to >recycle >"normal" components, which is also a good way to learn something. > >73 > >Francesco IS0FKQ One of those 4cx150s will do over 100W CW and the PS for that power is small. Like you say something different is always a draw. Allison KB1GMX Article: 94353 of rec.radio.amateur.homebrew From: " Uncle Peter" References: <1126653585.459065.41060@g43g2000cwa.googlegroups.com> Subject: Re: Big old-fashioned IF transformers for tube-type homebrewing? Message-ID: Date: Wed, 14 Sep 2005 15:09:19 -0400 "Scott Dorsey" wrote in message news:dg8b2p$hg6$1@panix2.panix.com... > Tim Shoppa wrote: > >Are the big old-fashioned IF transformers-in-a-can available > >anywhere anymore? I want to make a receiver, probably double > >conversion, > >which would mean that I'd want several each of the 50kHz and some > >higher frequency (455kHz likely). > > Try a hamfest, or Antique Electronics Supply. > > >Are these things that can be made from scratch without a lot of > >difficutly? I can wind coils etc. but don't > >have any transformer slug-tuned cores. > > They are a bloody pain. You should try it. If it was easy, it > wouldn't be fun. > --scott > -- > "C'est un Nagra. C'est suisse, et tres, tres precis." Getting the bandpass right could be a pain; I'd guess the sweet spot is near critical coupling, where you'd get a double-humped response curve. Otherwise, undercoupling would give you a sharper peak, good for CW, or you'd have to sweep align the strip for the desired BW. Pete Article: 94354 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: switching power mosfet as RF amplifiers Date: Wed, 14 Sep 2005 12:21:04 -0700 Message-ID: <11igu18j6chqf4c@corp.supernews.com> References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> <1dvdi1lqodbfnqvsvk7oh34vqgo8offr55@4ax.com> <1126686255.980443.67350@g49g2000cwa.googlegroups.com> <1126705718.554738.27190@g44g2000cwa.googlegroups.com> One thing I haven't heard mentioned is that the huge capacitances of power FETs are highly variable. They're essentially reverse-biased junction capacitances, so they change dramatically over the period of each cycle as the gate and drain voltages change. This tends to make them lossy, and makes them difficult or impossible to absorb them into a network. People have obviously found ways to live with the variable C, but it's not a trivial problem. Roy Lewallen, W7EL Article: 94355 of rec.radio.amateur.homebrew From: "Mauro" Subject: DDS and phase noise. Message-ID: Date: Wed, 14 Sep 2005 20:29:09 GMT I'm not an expert and need some help. I've build a DDS around an AD9951. I drive it at 400MHz from a source at 200MHz multiplied by 2. I get an output freq of 20MHz. I now drive it directly from the same source at 200MHz. I changed the register inside DDS to still get 20MHz on output. I do not have any possibility to measure the phase noise. So the question: is it possible to estimate if the phase noise of the 20MHz output is getting better, worst or is it going to remain the same? Thanks for the support. 73 Mauro Article: 94356 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> <1dvdi1lqodbfnqvsvk7oh34vqgo8offr55@4ax.com> <1126686255.980443.67350@g49g2000cwa.googlegroups.com> <1126705718.554738.27190@g44g2000cwa.googlegroups.com> <11igu18j6chqf4c@corp.supernews.com> Date: Wed, 14 Sep 2005 21:29:51 GMT On Wed, 14 Sep 2005 12:21:04 -0700, Roy Lewallen wrote: >One thing I haven't heard mentioned is that the huge capacitances of >power FETs are highly variable. They're essentially reverse-biased >junction capacitances, so they change dramatically over the period of >each cycle as the gate and drain voltages change. This tends to make >them lossy, and makes them difficult or impossible to absorb them into a >network. People have obviously found ways to live with the variable C, >but it's not a trivial problem. > >Roy Lewallen, W7EL Switching power MOSFETS are the current version of the "sweep tube" amplifier. Looking back those 6DQ5s and 6JS6s werent pretty either. Roger that, they are no fun to drive. The miller capacitance is also a similar factor and you have the same effect going on from the Drain Source path becuase of the avalanche diode. I suspect those combined effects are why the IMD for those single ended IRF510 amps are so pitiful. Driving them as pushpull pairs helps somewhat as you can get one and the other 180 out of phase to help reflect a passable reflection back to the driver. Allison Kb1GMX Article: 94357 of rec.radio.amateur.homebrew From: "xpyttl" References: Subject: Re: DDS and phase noise. Message-ID: Date: Wed, 14 Sep 2005 19:27:26 -0400 "Mauro" wrote in message news:pK%Ve.964$9l.18869@twister1.libero.it... > So the question: is it possible to estimate if the phase noise of the > 20MHz > output is getting better, worst or is it going to remain the same? Decreasing the frequency at which you clock the DDS will increase the phase noise. It is pretty hard to estimate as it will change quite a bit with small changes in divisor (i.e. output frequency). But as a general rule, you want to clock the DDS at some high multiple of the operating frequency. Obviously, if your clock has phase noise too, that is a bad thing. I would doubt that your frequency doubler would add phase noise, but I can't say for sure since I haven't got your circuit. But typically doublers introduce other forms of distortion which aren't as problematic for a DDS clock. So just shooting from the hip, I would expect your phase noise to be a lot worse from a 200 MHz clock than from the 400. It is still 10x the operating frequency, though, so I wouldn't expect it to be horrible. .. Article: 94358 of rec.radio.amateur.homebrew Message-ID: <4328BFC3.AEB27D2C@earthlink.net> From: "Michael A. Terrell" Subject: Re: Amphenol Microphone Connectors (Heathkit, etc.) References: <1126467283.868773.248440@g47g2000cwa.googlegroups.com> Date: Thu, 15 Sep 2005 00:25:58 GMT hhc314@yahoo.com wrote: > > Mike, the computers that I give to kids are equipped with GWBASIC and a > Microft C Compiler, so that they can acquire basic programming skills. > No Internet access, no games, simply things that will help them in > their later life. > > Harry C. The groups dealing with kids around here tell me that they have to have to have internet access for their school work. They asked for more than I can deliver, so I turned my efforts elsewhere, and left the other groups to help the kids. They already have every computer store in the area giving them everything, leaving nothing for others who need computers. My efforts are limited to an occasional mention in a weekly "Bulletin Board" column in the local news paper, and what Vets helping Vets has dropped off at their office. My church is trying to raise the money to buy and set up a used double wide portable classroom to teach free computer classes after school. The people giving computers to kids do just that, and walk away. The classes will start with the basics, then cover safe browsing. Classes for the kids will be right after school, and another session for adults in the evenings. Our recent work to help relocate refugees from Mississippi to this area have set the project back quite a bit, but it will happen. A smaller computer repair course will be offered to selected students who show an interest. It will be four hours a day on Saturday mornings to make sure they really want to take the course. I hope to take most of them to the point that they can pass the A+ certification at the end of the course. -- ? Michael A. Terrell Central Florida Article: 94359 of rec.radio.amateur.homebrew From: Justa Lurker Subject: Re: Use microwave oven chassis for a radio? References: Message-ID: Date: Thu, 15 Sep 2005 01:43:17 GMT Michael Black wrote: > > It was a nonsense reply, though I couldn't decide whether he was trolling > or actually didn't hav e a clue. > > Michael VE2BVW > Hardly the case Michael ---- Dr. Calhoun is a distinguished retired professor of Electrical Engineering at KSU. "Trolling and/or doesn't have a clue".....no, I really don't think so. His original post seemed serious, on-topic, and factually correct especially compared to some of the other crap that gets posted here. What made you think it might be otherwise ? 73s Article: 94360 of rec.radio.amateur.homebrew From: novatech@eskimo.com (Steven Swift) Subject: Re: DDS and phase noise. Date: 15 Sep 2005 01:45:19 GMT Message-ID: References: "Mauro" writes: >I'm not an expert and need some help. >I've build a DDS around an AD9951. >I drive it at 400MHz from a source at 200MHz multiplied by 2. I get an >output freq of 20MHz. >I now drive it directly from the same source at 200MHz. I changed the >register inside DDS to still get 20MHz on output. >I do not have any possibility to measure the phase noise. >So the question: is it possible to estimate if the phase noise of the 20MHz >output is getting better, worst or is it going to remain the same? >Thanks for the support. >73 >Mauro Assuming your source is not so good as to be below the noise floor of the AD9951, you will get slightly better performance without multiplying by two. The rule-of-thumb for perfect conversion is 6dB for each doubling. But it won't be perfect, so by doubling you'll be a little worse than 6dB and then dividing again you will not get as much back. If the doubling was perfect and the performance of the AD9951 was the same at 200MHz and 400MHz, you get the identical results. Of course, this might be bogus if there are other artifacts. Make sense? If you can build a doubler, then you can measure phase noise. Mix your 20MHz output with a known good 20MHz source in a double-balance mixer. Adjust the phase to get zero DC (quadrature). If you low-pass filter the output, the noise is an indication of phase noise. If you have a low frequency spectrum analyser available, you can get a nice plot. Otherwise you can use an AC voltmeter to get relative performance. Steve. -- Steven D. Swift, novatech@eskimo.com, http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA Article: 94361 of rec.radio.amateur.homebrew From: et472@FreeNet.Carleton.CA (Michael Black) Subject: Re: Use microwave oven chassis for a radio? Date: 15 Sep 2005 02:37:21 GMT Message-ID: References: Justa Lurker (JustaLurker@att.net) writes: > Michael Black wrote: >> >> It was a nonsense reply, though I couldn't decide whether he was trolling >> or actually didn't hav e a clue. >> >> Michael VE2BVW >> > > Hardly the case Michael ---- Dr. Calhoun is a distinguished retired > professor of Electrical Engineering at KSU. "Trolling and/or doesn't > have a clue".....no, I really don't think so. His original post seemed > serious, on-topic, and factually correct especially compared to some of > the other crap that gets posted here. What made you think it might be > otherwise ? > > 73s I can't be held responsible for top-posters. If you'd paid attention, the post I replied to was a top post, and he was referring to the nonsense reply to the original post. Note I specifically said "reply", as in " No, but the tube runs at a freq real close to ham Slow Scan TV bands. They retune them and use them as SSTV transmitters." which makes absolutely no sense, since SSTV is commonly used on HF. Michael VE2BVW Article: 94362 of rec.radio.amateur.homebrew From: mcalhoun@ksu.edu Subject: Re: Use microwave oven chassis for a radio? Date: 14 Sep 2005 22:39:43 -0500 Message-ID: References: >>I recently tore another microwave oven apart for the two really-strong >>....[snip].... >>and as I carried the rather bare chassis out to the garbage-can area, >>I wondered if anyone had ever tried built an amplifier in such a chassis >>-- maybe even using some of its many interlocks? >...[someone mentioned using the microwave tube...snip...]... I wasn't asking about re-using the microwave TUBE but the CHASSIS and maybe the interlocks and the cooling fan (I forgot to mention that in my original posting). If the new RF tube(s) would fit, the shielding at HF should be superb(!), yet one could still see the warm glow of the tubes through the grilled door. -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 94363 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: <08lii15cmpbn0c34mk204u2f3aq4pn82mr@4ax.com> References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> <1dvdi1lqodbfnqvsvk7oh34vqgo8offr55@4ax.com> <1126686255.980443.67350@g49g2000cwa.googlegroups.com> <1126705718.554738.27190@g44g2000cwa.googlegroups.com> <1126768800.174166.322400@z14g2000cwz.googlegroups.com> Date: Thu, 15 Sep 2005 11:04:48 GMT On 15 Sep 2005 01:01:40 -0700, francesco.messineo@gmail.com wrote: > >nospam@nouce.bellatlantic.net ha scritto: > >> On 14 Sep 2005 06:48:38 -0700, francesco.messineo@gmail.com wrote: >> >> > Hello, >> > >> > >> >nospam@nouce.bellatlantic.net ha scritto: >> > >> >> On 14 Sep 2005 01:24:16 -0700, francesco.messineo@gmail.com wrote: >> >> >> >> > > >> >> > >> >> >Reading from the ARF488 datasheet (this mosfet is made for RF >> >> >amplification >> >> >up to 60 MHz or so) I see input capacitance of 1400 pf typical, and >> >> >150 pf output capacitance typical. > >> >> >> >> Yes that is true. However that input capacitance is close to what I'd >> >> use to bypass a 50mhz circuit. It's near RF dead short unless you >> >> try to absorb it into the feed network. Even then it's a very low Z. >> > >> >Yes, I understand it. What isn't clear to me is why the ARF488 is >> >specified >> >for > 60 MHz and has input capacitance > of the one of an IRF840. >> >On QEX of may/jun 1999 you can find a 300W 50 MHz amplifier with >> >ARF488 push-pull. >> >> I'll check that one out. I do not have QEX back to '99 so it may take >> a while to get it. > >I can send you both the QEX article and the ARF488 datasheet (also the >IRF840 one, but this is really easy to find in the internet). Just >drop me an email and I'll send them, my email address is the one I'm >writing from. I have the IRF840 datasheet. The ARF488 datasheet is not on the 'net. Would like to see the QEX article. I have the arrl fowarding service. KB1GMX at Arrl . net Allison > >> >> I suspect the ARF488 is a RF rated varient of the IRFs and may offer >> other characteristice that are more complient at VHF. I cannot find >> any data or even a reference to ARF488. >> >> I am a 6m op that love to play on that band so curiousity always wins. > >same here. I've found that my 10W CW aren't terribly effective even >with >the 8m boom yagi lately, so I'm thinking about something more powerful >while the sun is sleeping. Seems like the old days when I could hear >and work VK with a J-pole are gone. > > > >> One of those 4cx150s will do over 100W CW and the PS for that power >> is small. Like you say something different is always a draw. > >Also these tubes need forced air cooling and the power supply would >need >to live near the amplifier (unless I want to send a cable with a kV up >to the antenna pole), if the mosfet way fails I'll probably go with an >expensive >bipolar amplifier or put the amplifier in the shack. > >73 >Francesco IS0FKQ Article: 94364 of rec.radio.amateur.homebrew From: John Ferrell Subject: Re: Use microwave oven chassis for a radio? Message-ID: <0ktii15rk1p71qtf2cu0gij0jjeeu5h30g@4ax.com> References: Date: Thu, 15 Sep 2005 13:37:57 GMT There was a fellow in Central Ohio in the late 80's that used a microwave oven as a fast scan TV transmitter on 2.4Ghz. The details are very hazy in my mind and I don't recall actually seeing his signal. He started with a new unit from a discount store. Feedline losses were a major problem, he eventually put the thing on top of the tower. Needless to say, experimenting with a tower mounted transmitter can bring a whole new set of problems. Especially one that heavy. I don't want to discourage tower mounting though. About the same time I had a QRP ATV transmitter at 1296mhz at the tower top that worked well. On Tue, 13 Sep 2005 20:20:57 -0400, sdeyoreo@hotmail.com wrote: >On 12 Sep 2005 23:01:40 -0500, mcalhoun@ksu.edu wrote: > >>I recently tore another microwave oven apart for the two really-strong >>magnets that are in the tube >> >> (they are fun to stack alternate-polarity on a wooden dowel >> so they seem to "float" in the air; kids of all ages just >> love to play that that "toy") >> >>(I kept the transformer, diode, capacitor, and misc. microswitches, too), >> >>and as I carried the rather bare chassis out to the garbage-can area, >>I wondered if anyone had ever tried built an amplifier in such a chassis >>-- maybe even using some of its many interlocks? >No, but the tube runs at a freq real close to ham Slow Scan TV bands. >They retune them and use them as SSTV transmitters. Article: 94365 of rec.radio.amateur.homebrew From: "Mike@Lincoln" Subject: Re: Big old-fashioned IF transformers for tube-type homebrewing? Date: Thu, 15 Sep 2005 15:39:10 +0000 (UTC) Message-ID: References: <1126653515.795787.34880@g43g2000cwa.googlegroups.com> "Tim Shoppa" wrote in message news:1126653515.795787.34880@g43g2000cwa.googlegroups.com... > Are the big old-fashioned IF transformers-in-a-can available > anywhere anymore? I want to make a receiver, probably double > conversion, > which would mean that I'd want several each of the 50kHz and some > higher frequency (455kHz likely). > > Are these things that can be made from scratch without a lot of > difficutly? I can wind coils etc. but don't > have any transformer slug-tuned cores. > > Tim KA0BTD > J.Birkett, 25, The Strait, LINCOLN. LN2 1JF. (Tel: 01522-520767 ) He had a few in the shop some months ago, failing that he often has old portable radios of 1960s vintage and he does not ask a great deal for them. Great little surplus shop of the old fashioned type....full of all kinds of junk . ( Closed Sun/Mon/Wed. ) Mike. Article: 94366 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: switching power mosfet as RF amplifiers Message-ID: References: <1126622313.323612.14380@g44g2000cwa.googlegroups.com> <1dvdi1lqodbfnqvsvk7oh34vqgo8offr55@4ax.com> <1126686255.980443.67350@g49g2000cwa.googlegroups.com> <1126705718.554738.27190@g44g2000cwa.googlegroups.com> <1126768800.174166.322400@z14g2000cwz.googlegroups.com> Date: Thu, 15 Sep 2005 17:35:44 GMT On 15 Sep 2005 01:01:40 -0700, francesco.messineo@gmail.com wrote: >I can send you both the QEX article and the ARF488 datasheet (also the >IRF840 one, but this is really easy to find in the internet). Just After looking at the data sheets and the apnote it confirms what I've said. The APT/ARF488 is a RF device and not close to the IRF parts. One difference easily noted is the lack of the avalanche diode present in the IRF parts. It's appearance spec wise is that of a low cost flavor of currently know RF types without the high cost package. I may add the ARF488 is unobtainium, apparently they have discontinued it and gone to newer versions. The apnote confirms the need for elaborate input match for a rather low input impedence that is highly reactive. The 50Mhz amplifier is not broadband and for 6m would be classified as very narrowband with it's specs covering on the 50-51mhz range. Their use of striplines to affect input match and output match contribute to the narrowband behavour. It is a high power amp at 300W with an IMD3 of -25dbm which is only ok, not great. You also need an 85V supply and have to deal with cooling both the supply and the amp. You could try an IRF parts in that circuit but read the apnote well as it explains the problems and techniques applied to overcome those problems at 50mhz. However the values required ot match the IRF vs the ARF parts may vary greater than the design limits resulting in poor performance. Allison KB1GMX Article: 94367 of rec.radio.amateur.homebrew From: "W3JDR" References: <3ibji1th4av4j4fhb0sdu6mtet8ctscd9t@4ax.com> Subject: Re: DDS and phase noise. Message-ID: Date: Thu, 15 Sep 2005 19:12:24 GMT >From what I've seen in the data sheets, the closer you operate the RF output to the Nyquist limit (Fref/2), the cleaner the spurs get. I've seen numbers of -90 dB or better on even some of the cheapo Analog Devices parts. Joe W3JDR "maxfoo" wrote in message news:3ibji1th4av4j4fhb0sdu6mtet8ctscd9t@4ax.com... > On Wed, 14 Sep 2005 20:29:09 GMT, "Mauro" wrote: > >>I'm not an expert and need some help. >>I've build a DDS around an AD9951. >>I drive it at 400MHz from a source at 200MHz multiplied by 2. I get an >>output freq of 20MHz. >>I now drive it directly from the same source at 200MHz. I changed the >>register inside DDS to still get 20MHz on output. >>I do not have any possibility to measure the phase noise. >>So the question: is it possible to estimate if the phase noise of the >>20MHz >>output is getting better, worst or is it going to remain the same? >>Thanks for the support. >>73 >>Mauro >> > > I won't be to concerned with phase noise, with that dds I'd be more > worried > about spurs. Those AD dds chips are notorious for them. Article: 94368 of rec.radio.amateur.homebrew Date: Thu, 15 Sep 2005 15:43:05 -0400 From: Bill Subject: Sir Douglas Hall Dec. 1943 article Message-ID: I'm looking for the complete article by Sir Douglas Hall of his "Battery-operated Communication 3-valver". It appeared in Decemeber 1943 Practical Wireless. The partial article is copied all over the net but only with the first three pages. Can anyone point me to a complete version? TIA, Bill Article: 94369 of rec.radio.amateur.homebrew From: "Mauro" References: Subject: Re: DDS and phase noise. Message-ID: Date: Thu, 15 Sep 2005 20:09:48 GMT Thanks to all who replied. I think that the net is that the phase noise should remain about the same. The source is a low noise quartz oscillator based on J.Stephensen design, followed by a Schottkey doubler and a MAR5 amplifier. I was in doubt to use or not the Schottkey doubler. I think i'll keep the simplest solution: no doubler. DDS max output will be 39MHz. A reference clock of 200MHz is still about 5 times the max output freq, high enought above the Nyquist limit. Thanks again. 73 Mauro i2SUH "Mauro" wrote in message news:pK%Ve.964$9l.18869@twister1.libero.it... > I'm not an expert and need some help. > I've build a DDS around an AD9951. > I drive it at 400MHz from a source at 200MHz multiplied by 2. I get an > output freq of 20MHz. > I now drive it directly from the same source at 200MHz. I changed the > register inside DDS to still get 20MHz on output. > I do not have any possibility to measure the phase noise. > So the question: is it possible to estimate if the phase noise of the 20MHz > output is getting better, worst or is it going to remain the same? > Thanks for the support. > 73 > Mauro > > Article: 94370 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA:Jennings JCS-250PF fxd caps + more Message-ID: Date: Thu, 15 Sep 2005 23:43:41 GMT 4 Jennings JCS-250 PF fixed vac caps + other stuff as well, see at: http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy Tnx for looking, heytubeguy Article: 94371 of rec.radio.amateur.homebrew Date: Fri, 16 Sep 2005 10:59:51 +0800 From: Richard Hosking Subject: Online PCB manufacturers Message-ID: <432a3527$0$12665$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Dear all As a hobbyist I am looking for advice re online PCBs Have not done any electronics for a couple of years. The board house I used to deal with locally has closed. They produced V good quality boards, but obviously couldnt compete with cheap Taiwanese/Chinese producers. I use the old Protel Autotrax circa 1991 - no interest in paying $3K for the latest software. I want good quality for SM packages to TQFP Mask/overlay Small runs up to 50 or so and prototypes 2-4 layers will accept Protel Autotrax as a format What do people use? Thanks Richard Article: 94372 of rec.radio.amateur.homebrew From: =?ISO-8859-1?Q?Per-=C5ke_Andersson?= Subject: Re: Triggering the HP 3585A spec analyzer Date: Fri, 16 Sep 2005 10:29:26 +0200 Message-ID: References: Johnson wrote: > what magnitude signal is necessary at the External Trigger Input of an > HP3585A. I am trying to get mine to work with my HP 3336B synthesizer. > > jack > > Trigger or reference ? This site: http://www.mjs-electronics.se/images/Hp/hp3585a.htm Says: External trigger input: negative going TTL level or contact closure required to initiate sweep External reference input: 10 MHz (or subharmonic to 1 MHz), 0 dBm minimum level /Per-Ake -- Remove "extra" in my e-mail Article: 94373 of rec.radio.amateur.homebrew Date: Fri, 16 Sep 2005 11:21:58 -0400 From: Bill Subject: Re: Sir Douglas Hall Dec. 1943 article References: Message-ID: <1d32$432ae319$4232bd13$3229@COQUI.NET> Bill wrote: > I'm looking for the complete article Found it, thanks. -Bill Article: 94374 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: solid state 6m amplifier Message-ID: References: <1126880193.099234.286630@f14g2000cwb.googlegroups.com> Date: Fri, 16 Sep 2005 18:08:16 GMT On 16 Sep 2005 07:16:33 -0700, francesco.messineo@gmail.com wrote: >Hello, > >having seen that's really difficult to make a working MOSFET linear >amplifier >for 6m, I started looking for a bipolar design and components. The >MRF448 >transistors seem very expensive. Can anyone suggest an alternate part >or >a different approach (not tubes, I wanted to put this amplifier at the >antenna)? >thanks > >Francesco IS0FKQ MRF492A usually under 22$US new and good for 70W or more. There are published designs using it that work well for all modes. Most of the VHF power mosfets are priced around $1US/Watt it seems and are dreadfully expensive compared to bipolars. Allison KB1GMX Article: 94375 of rec.radio.amateur.homebrew From: "Mauro" References: <3ibji1th4av4j4fhb0sdu6mtet8ctscd9t@4ax.com> Subject: Re: DDS and phase noise. Message-ID: Date: Fri, 16 Sep 2005 19:23:52 GMT I'm not going to use internal multiplier. I'm driving it at 200MHz directly. I agree that internal multiplier is adding noise. You can see that from the datasheet. Checked with an AOR7030 receiver the output seems to be quite clear and sharp. Not a real measurement, but better than some other PLL. 73 Mauro "Jim" wrote in message news:R-qdnZeKcaXn27feRVn-vw@comcast.com... > On Wed, 14 Sep 2005 20:29:09 GMT, "Mauro" wrote: > > >I'm not an expert and need some help. > >I've build a DDS around an AD9951. > >I drive it at 400MHz from a source at 200MHz multiplied by 2. I get an > >output freq of 20MHz. > >I now drive it directly from the same source at 200MHz. I changed the > >register inside DDS to still get 20MHz on output. > >I do not have any possibility to measure the phase noise. > >So the question: is it possible to estimate if the phase noise of the 20MHz > >output is getting better, worst or is it going to remain the same? > >Thanks for the support. > >73 > >Mauro > > > > > The AD9951 has a much better spur performance than earlier DDS chips, and > I have been tempted to use one for an LO in a radio, it looks clean enough > to work nicely. > > ============== > > Generally, I'd say your phase noise will be the same either way, and > perhaps even a little quieter with the 200 MHz clock. The internal > reference multipliers probably add a little phase noise, multipliers usually > do add a little extra noise, not than the normal 20log(N) one might expect > from theory. > > Reference multiplers DO allow running the DDS output to a higher > frequency, which is often a major desing goal, but if all you want is 20 MHz > output then you are fine with a 200 MHz reference. > > > Jim Pennell > N6BIU > > Article: 94376 of rec.radio.amateur.homebrew From: "Harold E. Johnson" References: <3ibji1th4av4j4fhb0sdu6mtet8ctscd9t@4ax.com> Subject: Re: DDS and phase noise. Message-ID: Date: Fri, 16 Sep 2005 21:11:39 GMT "Mauro" wrote in message news:cZEWe.5076$Jr.74108@twister2.libero.it... > I'm not going to use internal multiplier. I'm driving it at 200MHz > directly. > I agree that internal multiplier is adding noise. You can see that from > the > datasheet. > Checked with an AOR7030 receiver the output seems to be quite clear and > sharp. > Not a real measurement, but better than some other PLL. > 73 > Mauro The AOR 7030 uses a PLL. It has a dual tank VCO as G3SBI came up with. W4ZCB Article: 94377 of rec.radio.amateur.homebrew From: "Dan/W4NTI" References: <1126880193.099234.286630@f14g2000cwb.googlegroups.com> Subject: Re: solid state 6m amplifier Message-ID: Date: Fri, 16 Sep 2005 23:11:48 GMT Where can I find such a design? Dan/W4NTI wrote in message news:jd2mi1hqq5e83lifgoco245os1k0od3ksg@4ax.com... > On 16 Sep 2005 07:16:33 -0700, francesco.messineo@gmail.com wrote: > >>Hello, >> >>having seen that's really difficult to make a working MOSFET linear >>amplifier >>for 6m, I started looking for a bipolar design and components. The >>MRF448 >>transistors seem very expensive. Can anyone suggest an alternate part >>or >>a different approach (not tubes, I wanted to put this amplifier at the >>antenna)? >>thanks >> >>Francesco IS0FKQ > > MRF492A usually under 22$US new and good for 70W or more. There are > published designs using it that work well for all modes. > > Most of the VHF power mosfets are priced around $1US/Watt it seems > and are dreadfully expensive compared to bipolars. > > Allison > KB1GMX Article: 94378 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: solid state 6m amplifier Message-ID: References: <1126880193.099234.286630@f14g2000cwb.googlegroups.com> Date: Sat, 17 Sep 2005 03:33:01 GMT Try the ARRL website under TIS. It's called the "Compact 6M brick". It was published in the OCT 1990 QST. The circuit is very close to the Motorola test circuit for the device with bias for linear operation. FAR Circuits has the board for it. I think they can supply a reprint as well. If thats not enough power two of them with 2 port splitter/ combiners will get you better than anywhere from 150-180W. A Wilkinsen splitter and combiner is fairly easy to do at 6m either as lumped elements or maybe even coax. Allison KB1GMX On Fri, 16 Sep 2005 23:11:48 GMT, "Dan/W4NTI" wrote: >Where can I find such a design? > >Dan/W4NTI > > wrote in message >news:jd2mi1hqq5e83lifgoco245os1k0od3ksg@4ax.com... >> On 16 Sep 2005 07:16:33 -0700, francesco.messineo@gmail.com wrote: >> >>>Hello, >>> >>>having seen that's really difficult to make a working MOSFET linear >>>amplifier >>>for 6m, I started looking for a bipolar design and components. The >>>MRF448 >>>transistors seem very expensive. Can anyone suggest an alternate part >>>or >>>a different approach (not tubes, I wanted to put this amplifier at the >>>antenna)? >>>thanks >>> >>>Francesco IS0FKQ >> >> MRF492A usually under 22$US new and good for 70W or more. There are >> published designs using it that work well for all modes. >> >> Most of the VHF power mosfets are priced around $1US/Watt it seems >> and are dreadfully expensive compared to bipolars. >> >> Allison >> KB1GMX > Article: 94379 of rec.radio.amateur.homebrew From: "Steve H" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Date: Sat, 17 Sep 2005 11:28:18 +0100 Message-ID: <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> Looks a tad basic, http://www.amazon.co.uk/gp/reader/0750699469/ref=sib_dp_pt/202-6586683-0234256#reader-page "Polymath" wrote in message news:1126951418.730335.258350@g14g2000cwa.googlegroups.com... ISBN 0-7506-9946-9 "RF Circuit Deign" By Chris Bowick Pub. Newnes. I've just got a new copy from Ottakar's; it is still in print (just) £21-99pp for 176 pages packed full of concise info about RF circuits, LC filters (especially the bits about use of an L-network to match ant to TX) together with a good analysis of the Smiff (That's _TWO_ "f"'s) Chart and how to use it. This was recommended to me by my current employers (apparently the book is held in high regard in Japan). I only wish that I had come across it before. Article: 94380 of rec.radio.amateur.homebrew From: Frank Turner-Smith G3VKI Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> Message-ID: <5eSWe.10135$zw1.8300@newsfe2-gui.ntli.net> Date: Sat, 17 Sep 2005 10:29:21 GMT Poxy mouth wrote: > ISBN 0-7506-9946-9 > > "RF Circuit Deign" > By > Chris Bowick > > Pub. Newnes. > > I've just got a new copy from Ottakar's; it is > still in print (just) £21-99pp for 176 pages packed > full of concise info about RF circuits, LC filters > (especially the bits about use of an L-network to > match ant to TX) together with a good analysis of > the Smiff (That's _TWO_ "f"'s) Chart and how to use it. > Looks a better bargain than that £350 law book of yours. ...(_!_)... Article: 94381 of rec.radio.amateur.homebrew From: "Brian Reay" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Message-ID: Date: Sat, 17 Sep 2005 10:29:58 GMT "Steve H" wrote in message news:432befc1$1_4@mk-nntp-2.news.uk.tiscali.com... > Looks a tad basic, > http://www.amazon.co.uk/gp/reader/0750699469/ref=sib_dp_pt/202-6586683-0234256#reader-page > > "Polymath" wrote in message > news:1126951418.730335.258350@g14g2000cwa.googlegroups.com... > ISBN 0-7506-9946-9 > > "RF Circuit Deign" > By > Chris Bowick > > > This was recommended to me by my current employers (apparently > the book is held in high regard in Japan). I only > wish that I had come across it before. I have to agree Steve, a tad basic. Unless, of course, your employer has spotted you lack the basics. -- 73 Brian, G8OSN www.g8osn.org.uk Article: 94382 of rec.radio.amateur.homebrew From: "Dlawson" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Message-ID: Date: Sat, 17 Sep 2005 11:29:48 GMT "Polymath" wrote in message news:1126951418.730335.258350@g14g2000cwa.googlegroups.com... This was recommended to me by my current employers (apparently the book is held in high regard in Japan) Not only are you reduced to working for a shower of murdering Japanese bastards, but you were recomended to go sit in a corner read a book and brush up on your maths. ROTFLMFAO Article: 94383 of rec.radio.amateur.homebrew From: Frank Turner-Smith G3VKI Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126954864.731710.43720@g47g2000cwa.googlegroups.com> Message-ID: Date: Sat, 17 Sep 2005 11:41:45 GMT Poxy mouth wrote: > > Now, Brian, here's that opportunity for you to put your money > where your mouth is.....which particular parts of the book do > you "agree..... are a tad basic". Please reply within 2 minutes so > that you don't have time to consult the book (perhaps for the > very first time?), or else be seen for ever hereafter as a > laughing stock, and a LIAR. > How do you expect him to tell you which particular parts of the book he considers 'a tad basic' without consulting the book to quote chapter, page, paragraph etc.? Your post of 11:03 today describes it as '...full of concise info...', what does that suggest to you? ...(_!_)... Article: 94384 of rec.radio.amateur.homebrew From: "Steve H" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Date: Sat, 17 Sep 2005 14:05:58 +0100 Message-ID: <432c14b5$1_2@mk-nntp-2.news.uk.tiscali.com> "Polymath" wrote in message news:1126956334.407558.33070@g14g2000cwa.googlegroups.com... > There are a number of rather silly and infantile people > whose first inclination is to sneer. Two such intellectual > failures are quoted below; "Empty vessels make the > most noise". A book whose first page is about > wire, the skin effect thereto, and the inductance of a short > length of wire is not basic by any means. You should already know all of the above after 30 years of hamming it up. Basic. Looks like a good book for anyone starting out in radio with a good basic education or a good crib sheet for the rest of us. Sitting in the sun with a half full vessel reading Traveling wave antennas by Carlton H Walter, includes an interesting discussion of the polyrod antenna ;c) Steve H Article: 94385 of rec.radio.amateur.homebrew From: Frank Turner-Smith G3VKI Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> Message-ID: Date: Sat, 17 Sep 2005 13:11:15 GMT Poxy mouth wrote: A book whose first page is about > wire, the skin effect thereto, and the inductance of a short > length of wire is not basic by any means. > BWAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA! If that's not basic I'd like to know what is. Is your knowledge so limited you see these as advanced subjects? Oh, why did I bother to ask? I know the answer. ...(_!_)... Article: 94386 of rec.radio.amateur.homebrew From: "Brian Reay" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Message-ID: <9_VWe.422$bR.1@newsfe7-win.ntli.net> Date: Sat, 17 Sep 2005 14:45:25 GMT "Frank Turner-Smith G3VKI" wrote in message news:TBUWe.404$bR.291@newsfe7-win.ntli.net... > Poxy mouth wrote: > A book whose first page is about >> wire, the skin effect thereto, and the inductance of a short >> length of wire is not basic by any means. >> > BWAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA! > If that's not basic I'd like to know what is. I have to agree Frank, the fundamental reason why a wire has inductance is a very basic fact, I believe taught at KS3 science. Makes you wonder about degrees from the UoE, does it not? -- 73 Brian, G8OSN www.g8osn.org.uk Article: 94387 of rec.radio.amateur.homebrew From: "Steve H" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Date: Sat, 17 Sep 2005 17:14:06 +0100 Message-ID: <432c40cd$1_2@mk-nntp-2.news.uk.tiscali.com> "Polymath" wrote in message news:1126971523.139315.3360@g49g2000cwa.googlegroups.com... > That you sneer at attempts to introduce Radio Hams to > materials for advancement is a very good illustration > of why anybody who holds, or who has ever held, a licence > issued under the gangrenous degeneration that is the M3/CB > Fools' Licence scheme will _NEVER_ make it into the > ranks of _REAL_ Radio Hams. It looks to be a good book for the newcomer to RF design giving readers a basic understanding of the fundamentals, but the question is - Why would someone with your 30+ years of experience as a real radio ham find useful? Steve H Article: 94388 of rec.radio.amateur.homebrew From: Conrad Poos Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> Message-ID: <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> Date: Sat, 17 Sep 2005 16:53:19 GMT Bleedin' hell.....talk about typing in Beanies launch code! Poos -- vy 73 de Conrad Poos "Ich bin ein radio amateur" Article: 94389 of rec.radio.amateur.homebrew From: "MattD.." Subject: Re: Recommended reading for _REAL_ Radio Hams Date: Sat, 17 Sep 2005 18:27:08 +0100 Message-ID: References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> On Saturday 17 Sep 2005 17:53, the world held its breath whilst Conrad Poos delivered the following wit: > Bleedin' hell.....talk about typing in Beanies launch code! Indeed, Mr. Poos. One wonders if this pair aren't best left on their own, since they seem to thrive on this. Perhaps it's an inferiority complex that keeps them both at it... Or it could be love :-) -- Radio glossary #53 Battery: Commonly phrased with "assault", this is usually the result of the annual repeater group get-together. Article: 94390 of rec.radio.amateur.homebrew From: "Brian Reay" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> Subject: Re: Recommended reading for _REAL_ Radio Hams Message-ID: Date: Sat, 17 Sep 2005 17:34:34 GMT "Conrad Poos" wrote in message news:3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk... > Bleedin' hell.....talk about typing in Beanies launch code! > Good, "in ' it" ;-) Next thing you know he'll be standing in a cell with a blanket on his head or faking chest pains! -- 73 Brian, G8OSN www.g8osn.org.uk Article: 94391 of rec.radio.amateur.homebrew From: "Brian Reay" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <432c40cd$1_2@mk-nntp-2.news.uk.tiscali.com> Subject: Re: Recommended reading for _REAL_ Radio Hams Message-ID: Date: Sat, 17 Sep 2005 17:42:07 GMT "Steve H" wrote in message news:432c40cd$1_2@mk-nntp-2.news.uk.tiscali.com... > "Polymath" wrote in message > news:1126971523.139315.3360@g49g2000cwa.googlegroups.com... >> That you sneer at attempts to introduce Radio Hams to >> materials for advancement is a very good illustration >> of why anybody who holds, or who has ever held, a licence >> issued under the gangrenous degeneration that is the M3/CB >> Fools' Licence scheme will _NEVER_ make it into the >> ranks of _REAL_ Radio Hams. > > It looks to be a good book for the newcomer to RF design giving readers a > basic understanding of the fundamentals, but the question is - Why would > someone with your 30+ years of experience as a real radio ham find useful? Fair comment Steve and a good question. -- 73 Brian, G8OSN www.g8osn.org.uk Article: 94392 of rec.radio.amateur.homebrew From: "EL84" Subject: Re: Recommended reading for _REAL_ Radio Hams Date: Sat, 17 Sep 2005 19:01:50 +0100 Message-ID: <3p340dF8ehfuU1@individual.net> References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <1126959533.085217.266940@o13g2000cwo.googlegroups.com> "Polymath" wrote in message news:1126959533.085217.266940@o13g2000cwo.googlegroups.com... > Does "EL84" know that you are pirating her > Internet Address (82.42.159.143)? Oh dear what am I to do ? If you had a clue Beanie you would know how easy it is to, change, copy, or clone an IP address, don't tell me you don't know how its done old fruit. Article: 94393 of rec.radio.amateur.homebrew From: Frank Turner-Smith G3VKI Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> <1126981575.264517.174350@f14g2000cwb.googlegroups.com> Message-ID: Date: Sat, 17 Sep 2005 19:10:19 GMT Brian Reay wrote: > >>Good, "in ' it" ;-) >> >>Next thing you know he'll be standing in a cell with a blanket on his head >>or faking chest pains! > Poxy mouth scrawled: > What on earth are you on about now? > > Making up more stories? > Hmmm...why your interest, Beanie? ...(_!_)... Article: 94394 of rec.radio.amateur.homebrew From: Frank Turner-Smith G3VKI Subject: Re: Notice to BRIAN REAY (Was Re: Recommended reading for _REAL_ References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> <1126989833.302183.49430@g14g2000cwa.googlegroups.com> Message-ID: Date: Sat, 17 Sep 2005 22:32:54 GMT Poxy mouth poured herself another drink and scrawled drunkenly: < retarded crap snipped > > There remains no doubt that because of your publicly-expressed > obsession with sheep-shagging that you are a danger to children... only to lambs, by your 'reasoning' < more retarded crap snipped > > > For the last and final time, I invite you to publicly and > unconditionally retract and apologise for your scurrilous > remarks about sheep-shagging and your other remarks about > drinking methylated spirit. I urge you to do this whilst > you still have a free choice in the matter. > > I will not ask you again, but if you do not retract and > apologise then I will seek redress from you by > means that are legal and decent, concepts that seem > to be quite alien to you. straight out of your £350 law book, no doubt. > Blimey Beanie, I bet he's scared now! Are you gonna set the TAFIA onto him? FOAD, twat. ...(_!_)... Article: 94395 of rec.radio.amateur.homebrew From: Wankel Rotary Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126954864.731710.43720@g47g2000cwa.googlegroups.com> <1126955197.353204.259710@g14g2000cwa.googlegroups.com> Message-ID: Date: Sat, 17 Sep 2005 23:51:58 GMT Polymath wrote: > No reply from Brian Reay, who thus may be taken > as a liar and a bullshitter (if he wasn't so taken > already). > > All mouth and trousers. We don't all have empty lives like you that enable us to sit and spout shit on the internet all day. Seeing Brian is a 'teacher', at least he has a career and not a job. Stupid Boy! Have you missed taking all of your lithium today perchance? WR. Article: 94396 of rec.radio.amateur.homebrew From: Wankel Rotary Subject: Re: Notice to BRIAN REAY (Was Re: Recommended reading for _REAL_ References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> <1126989833.302183.49430@g14g2000cwa.googlegroups.com> Message-ID: Date: Sat, 17 Sep 2005 23:56:02 GMT Polymath wrote: > I will not ask you again, but if you do not retract and > apologise then I will seek redress from you by > means that are legal and decent, concepts that seem > to be quite alien to you. I bet you've really got Brian running scared now Mr Gareth Evans. Bwahahahahahaaaa!!! Article: 94397 of rec.radio.amateur.homebrew From: "SOMMERGIBILE" Subject: A lot of good diagrams Date: Sun, 18 Sep 2005 10:04:07 +0200 Message-ID: <432d21f7$1$8486$5fc30a8@news.tiscali.it> on: http://web.tiscali.it/am2zy/index.html Article: 94398 of rec.radio.amateur.homebrew From: "jim.gm4dhj" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> <1126989833.302183.49430@g14g2000cwa.googlegroups.com> Subject: Re: Notice to BRIAN REAY (Was Re: Recommended reading for _REAL_ Radio Hams) Message-ID: Date: Sun, 18 Sep 2005 09:03:37 GMT "Polymath" wrote in message news:1126989833.302183.49430@g14g2000cwa.googlegroups.com... > If that is your admission that it is your intention > to stir things up, then your behaviour is shameful. > > Is it not enough for you that you subjected me and my family > to a two-year period of grossly offensive remarks > about sheep-shagging, and then, when you were outed > by the suggestion that such behaviour meant that you > were unsuited to being a school teacher > that you made malicious, misleading and therefore > perjurous complaints to the plods that caused a great > deal of further distress to me and my family? > > Is it not enough for you that one plod is now facing a > criminal prosecution for assault and that a further 54 > complaints are outstanding against other plods as the > direct result of you inciting them with your lies? > > Was this shameful behaviour insufficient for you that > you must now continue with your infantile jibes, with > your stated deliberate intention as quoted below? > > There remains no doubt that because of your publicly-expressed > obsession with sheep-shagging that you are a danger to children > and that under no circumstances should you be employed as a > teacher of mathematics in Strood, Kent, or, indeed, in any other place. > > For the last and final time, I invite you to publicly and > unconditionally retract and apologise for your scurrilous > remarks about sheep-shagging and your other remarks about > drinking methylated spirit. I urge you to do this whilst > you still have a free choice in the matter. > > I will not ask you again, but if you do not retract and > apologise then I will seek redress from you by > means that are legal and decent, concepts that seem > to be quite alien to you. I know what you mean... you get your boss and top coucilors after you and before you know it you loose your job ........... Article: 94399 of rec.radio.amateur.homebrew From: Wankel Rotary Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> Message-ID: Date: Sun, 18 Sep 2005 13:02:07 GMT Polymath wrote: > ISBN 0-7506-9946-9 > > "RF Circuit Deign" > By > Chris Bowick > > Pub. Newnes. > > I've just got a new copy from Ottakar's; it is > still in print (just) £21-99pp for 176 pages packed > full of concise info about RF circuits, LC filters > (especially the bits about use of an L-network to > match ant to TX) together with a good analysis of > the Smiff (That's _TWO_ "f"'s) Chart and how to use it. > > This was recommended to me by my current employers (apparently > the book is held in high regard in Japan). I only > wish that I had come across it before. So the person who appears to know everything about amateur radio, electronics and life in general, didn't know about such a good book? If your employers had to recommend it, do you have a lack of knowledge somewhere? Do they know the manner in which you post and contribute to this newsgroup? Do they also know your track record with the Well-Shite Constabulary? Your stance on Lillibet Windsor and Royalty? People in general? Partakers of the same hobby as you - 'ham'(sic!) radio - which supposedly encourages working together and collaboration - despite you detesting certain classes of the hobby instead of encouraging them to further themselves? I expect, especially if your employers are Japanese, they encourage working together and the value of fellow man? Also, if your employers are Japanese, surely you must have some stance on working for those you detest - murders, warmongers and out and out torturers in the past? Double standards Gareth deary.....tut tut.... WR. Article: 94400 of rec.radio.amateur.homebrew From: Wankel Rotary Subject: Re: Recommended reading for _REAL_ Radio Hams References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <1126975249.840576.262850@f14g2000cwb.googlegroups.com> <1127010670.606194.110480@g43g2000cwa.googlegroups.com> Message-ID: Date: Sun, 18 Sep 2005 13:13:46 GMT eternalsquire@comcast.net wrote: > Who cares what a real ham is or isn't? Why does this argument even > matter? Why can't we all just be friends and have fun? In the real world - yes. In Gareth's head - never! Article: 94401 of rec.radio.amateur.homebrew From: "DXer" References: <1126951418.730335.258350@g14g2000cwa.googlegroups.com> <432befc1$1_4@mk-nntp-2.news.uk.tiscali.com> <1126956334.407558.33070@g14g2000cwa.googlegroups.com> <9_VWe.422$bR.1@newsfe7-win.ntli.net> <1126971523.139315.3360@g49g2000cwa.googlegroups.com> <1126973592.999298.282640@z14g2000cwz.googlegroups.com> <3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk> Subject: Re: Recommended reading for _REAL_ Radio Hams Date: Sun, 18 Sep 2005 13:24:12 -0000 Message-ID: <432d6ab3$0$12172$cc9e4d1f@news-text.dial.pipex.com> "Conrad Poos" wrote in message news:3SXWe.40151$k22.38019@fe2.news.blueyonder.co.uk... > Bleedin' hell.....talk about typing in Beanies launch code! > Yep - he's gone Ballistic. Don't worry he'll be back soon to recommend a book on Basic Rocket Science! PS Anyone got his Keplerian Elements - if the sky is clear you might even see him as he goes overhead. Article: 94402 of rec.radio.amateur.homebrew From: "William E. Sabin" References: Subject: Re: transformer basic question Message-ID: Date: Sun, 18 Sep 2005 17:47:09 GMT If the transformer has a step-up turns ratio (from primary to secondary) then the resistance, inductive reactance and capacitive reactance connected to the secondary (as measured at the primary) decrease as the square of the turns ratio. Therefore effective capacitance measured at the primary increases as the square of the turns ratio. For a step-down transformer the effects are the opposite. Bill W0IYH wrote in message news:ej6ri154ombo5lcsgjhfcp16spjimj8cb8@4ax.com... > Is the value of a capacitor placed in series with the secondary of a > transformer multiplied (as viewed from the primary) by the turns ratio > or the square of the turns ratio? > > Thanks, > > T Article: 94403 of rec.radio.amateur.homebrew From: "William E. Sabin" References: Subject: Re: transformer basic question Message-ID: Date: Sun, 18 Sep 2005 22:29:43 GMT Your original question suggested an ideal transformer, which the loop antenna undoubtedly is not, therefore the detailed answer is more complicated. The loop impedance is an LCR network that would require a more detailed study, which I am not able to offer right now. If your 1000 pF gets the job done, that is probably a good solution that tunes out the net effective inductive reactance. Bill W0IYH wrote in message news:b1dri15jugkl3gcsd5n406krn8esah5kn2@4ax.com... > On Sun, 18 Sep 2005 17:47:09 GMT, "William E. Sabin" > wrote: > >>If the transformer has a step-up turns ratio (from primary to secondary) >>then the resistance, inductive reactance and capacitive reactance >>connected >>to the secondary (as measured at the primary) decrease as the square of >>the >>turns ratio. Therefore effective capacitance measured at the primary >>increases as the square of the turns ratio. For a step-down transformer >>the >>effects are the opposite. >> > > OK Bill, > > I have a series tuned loop that is resonant with 1000 pf and fed into > a 10 to one step up transformer. > > If I remove the 1000 pF cap completely, I can resonate the loop at the > same frequency with 10 pF in the secondary? > > It almost sounds too good to be true:>: > > Regards, > > T Article: 94404 of rec.radio.amateur.homebrew Date: Mon, 19 Sep 2005 08:02:02 +0200 From: Ro Subject: Re: Sir Douglas Hall Dec. 1943 article References: <1d32$432ae319$4232bd13$3229@COQUI.NET> Message-ID: <432e5446$0$12714$ba620dc5@text.nova.planet.nl> Bill wrote: > Bill wrote: > >> I'm looking for the complete article > > > Found it, thanks. > > -Bill Where did you find it? Roland