20070725.ba v04_n072.bam.20070725 >From ???@??? Tue Jul 24 20:27:34 2007 -0500 Date: Wed, 25 Jul 2007 01:26:59 GMT From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4072 Message-Id: <20070725012700.23F4C470162@srvr1.theporch.com> BOATANCHORS Digest 4072 Topics covered in this issue include: 1) FS: Hickok TV Tube Test Adaptor by WA5CAB@cs.com 2) BC-224 owners, X-hut by stuck in 50s 3) is a 5591 a 6AK6? by john 4) Re: is a 5591 a 6AK6? by David Hollander 5) Re: is a 5591 a 6AK6? by john 6) FW: Collins tool set 51JX R-388 by "Thomas Frobase" 7) Re: Warning! Virus! Collins tool set 51JX R-388 by John Dilks K2TQN 8) Re: Collins / web calamity!!!!! by stuck in 50s 9) Re: Collins / web calamity!!!!! by "B. Smith" 10) crystals- Heath SB 313 by wb3fau@att.net 11) Re: Collins / web calamity!!!!! by stuck in 50s 12) Re: crystals- Heath SB 313 by Scott Robinson 13) Re: crystals- Heath SB 313 by w1id@comcast.net 14) Capacitor Question by Jim Garland <4cx250b@muohio.edu> 15) Re: Capacitor Question by wb3fau@att.net 16) Re: Capacitor Question by Scott Robinson 17) Transformers for Collins PM-2 by W6cds@aol.com 18) Re: Capacitor Question by "Arden Allen" 19) Re: Capacitor Question by Jim Garland <4cx250b@muohio.edu> 20) Re: Capacitor Question by "Al Parker" 21) Re: Capacitor Question by "Arden Allen" 22) Virus Alert http://www.kitparts.com by "Thomas Frobase" 23) Re: Capacitor Question by "Tom Rauch" ---------------------------------------------------------------------- From: WA5CAB@cs.com Message-ID: Date: Sat, 21 Jul 2007 18:04:06 EDT Subject: FS: Hickok TV Tube Test Adaptor To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_ca0.16943e31.33d3dcd6_boundary" --part1_ca0.16943e31.33d3dcd6_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Box has what looks like 1050-114 written on end (plus some writing indicating it once belonged to the E-Shop 56 at a Naval Shipyard). No ID on the unit itself. C/o a multiconductor cord with octal plug on one end and a large double ended socket on the other. One end of the socket has that very large 12-pin arrangement used on old CRT's. The other end has what looks like a standard 9-pin miniature socket. Coming out the other side of the socket is a length of red test-lead ending in an alligator clip. There is an adaptor marked 110 deg. CRT Conversion Adaptor that plugs into the 12-pin socket. Other end of it is an 8-pin socket (not octal). Also marked Code No 1050-108. $20 OBO plus shipping. Robert Downs - Houston (Web Store) MVPA 9480 (Primary email) (Backup email) --part1_ca0.16943e31.33d3dcd6_boundary Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * --part1_ca0.16943e31.33d3dcd6_boundary-- ------------------------------ Date: Sun, 22 Jul 2007 08:28:35 -0400 (EDT) From: stuck in 50s Message-Id: <200707221228.l6MCSZKe029743@fracas.netboobie.org> To: Old Tube Radios Subject: BC-224 owners, X-hut X is roman for 10 & saying goes "when in Rome...." well I confess, I'm not even in Rome, Ga. I bet there's a lot of y'all that have the things. Pse drop a line whether or not it's burning a hole in ur pocket Tnx aa4rm aka Marty ------------------------------ Message-Id: <6.2.1.2.2.20070722084552.03d13eb0@pop-server.nc.rr.com> Date: Sun, 22 Jul 2007 08:47:00 -0400 To: Old Tube Radios From: john Subject: is a 5591 a 6AK6? Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed I am trying to verify whether a 5591 is indeed a 6AK6....anyone have a cross over list between these industrial/Mil numbers to commercial? Thanks John K5MO ------------------------------ Message-ID: <46A353FB.5010103@cox.net> Date: Sun, 22 Jul 2007 05:56:27 -0700 From: David Hollander MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: is a 5591 a 6AK6? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi John - a 5591 is like a 6AK5 according to this link http://www.nj7p.org/Tube4.php?tube=5591 73, Dave N7RK -- *********************************************************** Dave N7RK Boatanchors Home Page: http://members.cox.net/n7rk Phoenix, Arizona *DXCC Honor Roll* *WAZ#22 - 75 Meter SSB* ex-XE2/N7RK, N7RK/ZB2, VK2ERK, ZM0AJN, WB6NRK, WN6IWX Boatanchor and Antique Radio Collector ------------------------------ Message-Id: <6.2.1.2.2.20070722090022.03d10950@pop-server.nc.rr.com> Date: Sun, 22 Jul 2007 09:00:30 -0400 To: Old Tube Radios From: john Subject: Re: is a 5591 a 6AK6? Cc: Old Tube Radios Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Perfect! Thanks Dave John At 08:56 AM 7/22/2007, David Hollander wrote: >Hi John - a 5591 is like a 6AK5 according to this link > >http://www.nj7p.org/Tube4.php?tube=5591 > >73, > >Dave N7RK >-- >*********************************************************** >Dave N7RK Boatanchors Home Page: http://members.cox.net/n7rk >Phoenix, Arizona *DXCC Honor Roll* *WAZ#22 - 75 Meter SSB* > >ex-XE2/N7RK, N7RK/ZB2, VK2ERK, ZM0AJN, WB6NRK, WN6IWX > >Boatanchor and Antique Radio Collector ------------------------------ From: "Thomas Frobase" To: Old Tube Radios Subject: FW: Collins tool set 51JX R-388 Date: Sun, 22 Jul 2007 18:33:37 -0500 Message-ID: <0a5601c7ccb8$bb9f5a60$0c01010a@tfrobase1> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0A57_01C7CC8E.D2C95260" This is a multi-part message in MIME format. ------=_NextPart_000_0A57_01C7CC8E.D2C95260 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I have completed the next run of tool sets for the Collins 51J Series and R-388. If you are still interested in a set please visit my web site at http://www.kitparts.com I have set up a PayPal link, checks or money orders may be sent to the address listed below. If you are sending a payment please indicate by email and I will set the tools aside for you! I also am shipping rectifier replacements for these radios, see the web site . thanks tom, N3LLL Kitparts Thomas L. Frobase 4770 Oakmont Court League City TX 77573 ------=_NextPart_000_0A57_01C7CC8E.D2C95260 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ------=_NextPart_000_0A57_01C7CC8E.D2C95260-- ------------------------------ Date: Mon, 23 Jul 2007 05:06:01 -0400 To: Old Tube Radios From: John Dilks K2TQN Subject: Re: Warning! Virus! Collins tool set 51JX R-388 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Message-Id: <20070723091037.5BCB3470157@srvr1.theporch.com> Twice I tried to open this web page and received a McAfee alert that there is a Trojan Horse Virus (a .mov file), which McAfee deleted and closed the web page. The first problem indication is, it asks me to click a box to open Active X, then the Error pops up from McAfee. I caution all to stay away from this web page until Tom gets it fixed. If you don't have McAfee to protect your computer you may be at risk. 73, John Dilks, K2TQN t 07:33 PM 7/22/2007, Thomas Frobase wrote: >I have completed the next run of tool sets for the Collins 51J Series and >R-388. If you are still interested in a set please visit my web site at >http://www.kitparts.com I have set up a PayPal >link, checks or money orders may be sent to the address listed below. If >you are sending a payment please indicate by email and I will set the tools >aside for you! > >I also am shipping rectifier replacements for these radios, see the web site >. thanks tom, N3LLL >Kitparts >Thomas L. Frobase >4770 Oakmont Court >League City TX 77573 ------------------------------ Date: Mon, 23 Jul 2007 08:17:24 -0400 (EDT) From: stuck in 50s Message-Id: <200707231217.l6NCHOR1005825@fracas.netboobie.org> To: Old Tube Radios Subject: Re: Collins / web calamity!!!!! Yo Tom F I'm looking @ www.kitparts.com thru picky firefox browser on Balmer-soft XP. Not a hiccup Cud it be that K2TQN's virus s/w just trying to justify it's presence by "crying wolf?" Marty ------------------------------ Message-ID: <000d01c7cd25$9d95e940$e9e1a243@HAL1000> From: "B. Smith" To: Old Tube Radios Subject: Re: Collins / web calamity!!!!! Date: Mon, 23 Jul 2007 08:33:03 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit Here is what I get when I access the site running McAfee. breck k4che ---------------------------------------------------------------------------------------------------------------- McAfee has automatically blocked and removed a potentially harmful script. Details Detection: JS/Exploit-BO.gen (Virus) More Info Scripts typically run when you let programs act on your behalf, such as when you connect a personal handheld device to your computer, when you connect your computer to the Internet, or when you surf the Web. However, some scripts can act unexpectedly. Suspect activity might include creating, copying, or removing files, or opening the Windows registry. -----------------------------------------------------------------------------------------------| | I'm looking @ www.kitparts.com | | thru picky firefox browser on Balmer-soft XP. Not a hiccup | | Cud it be that K2TQN's virus s/w just trying to justify it's presence | by "crying wolf?" | | Marty | ------------------------------ From: wb3fau@att.net To: Old Tube Radios Subject: crystals- Heath SB 313 Date: Mon, 23 Jul 2007 19:35:28 +0000 Message-Id: <072320071935.1858.46A502FF000C4B630000074221602807489A0E00CC0D99@att.net> Having acquired a Heath SB line rx, 1st time ever, something new for me. A few bands are dead, found 2 dead het. osc. crystals- 12.395mc. The other - 22.895mc. Maybe I should go look for Heath users group? I have a small box of xtals accumilated over time, no luck. I think there is probably someone out there who has these in their goodie collection? Please email me if you have these. thanks Russ. ------------------------------ Date: Mon, 23 Jul 2007 16:55:32 -0400 (EDT) From: stuck in 50s Message-Id: <200707232055.l6NKtWx5007900@fracas.netboobie.org> To: Old Tube Radios Subject: Re: Collins / web calamity!!!!! Damn the torpedoes breck, full steam ahead I still stand on my artificial McAfee worry-wart opinion ------------------------------ Mime-Version: 1.0 Message-Id: Date: Mon, 23 Jul 2007 15:49:28 -0700 To: Old Tube Radios From: Scott Robinson Subject: Re: crystals- Heath SB 313 Content-Type: text/plain; charset="us-ascii" ; format="flowed" Hi Russ, Before you go buying crystals, do the part of the alignment where you adjust a coil to go with every crystal; you might save some money and time. Peace, Scott, who owns an SB310, the hollow state version of the 313. At 7:35 PM +0000 7/23/07, wb3fau@att.net wrote: >Having acquired a Heath SB line rx, 1st time ever, something >new for me. A few bands are dead, found 2 dead het. osc. >crystals- 12.395mc. The other - 22.895mc. Maybe I should go >look for Heath users group? I have a small box of xtals >accumilated over time, no luck. I think there is probably someone >out there who has these in their >goodie collection? Please email me if you have these. thanks Russ. ------------------------------ From: w1id@comcast.net To: Old Tube Radios Cc: Scott Robinson Subject: Re: crystals- Heath SB 313 Date: Tue, 24 Jul 2007 11:58:12 +0000 Message-Id: <072420071158.25488.46A5E9540004B5C10000639022007504380B07CE99@comcast.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_25488_1185278292_0" --NextPart_Webmail_9m3u9jl4l_25488_1185278292_0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Those would be the 80 and 20 meter crystals. Any SB line receiver or transmitter as well as the HW-100/101 use the same crystals. As Scott mentions, check the alignment of the heterodyne oscillator. I hope all the dual gate MOSFETS are OK, if not, they are extremely hard to find and very expensive once you do find them. -------------- Original message -------------- From: Scott Robinson > Hi Russ, > > Before you go buying crystals, do the part of the alignment where you > adjust a coil to go with every crystal; you might save some money and > time. > > Peace, > > Scott, who owns an SB310, the hollow state version of the 313. > > At 7:35 PM +0000 7/23/07, wb3fau@att.net wrote: > >Having acquired a Heath SB line rx, 1st time ever, something > >new for me. A few bands are dead, found 2 dead het. osc. > >crystals- 12.395mc. The other - 22.895mc. Maybe I should go > >look for Heath users group? I have a small box of xtals > >accumilated over time, no luck. I think there is probably someone > >out there who has these in their > >goodie collection? Please email me if you have these. thanks Russ. > --NextPart_Webmail_9m3u9jl4l_25488_1185278292_0 Content-Type: text/html Content-Transfer-Encoding: 8bit
Those would be the 80 and 20 meter crystals. Any SB line receiver or transmitter as well as the HW-100/101 use the same crystals. As Scott mentions, check the alignment of the heterodyne oscillator. I hope all the dual gate MOSFETS are OK, if not, they are extremely hard to find and very expensive once you do find them.
-------------- Original message --------------
From: Scott Robinson <spr@earthlink.net>

> Hi Russ,
>
> Before you go buying crystals, do the part of the alignment where you
> adjust a coil to go with every crystal; you might save some money and
> time.
>
> Peace,
>
> Scott, who owns an SB310, the hollow state version of the 313.
>
> At 7:35 PM +0000 7/23/07, wb3fau@att.net wrote:
> >Having acquired a Heath SB line rx, 1st time ever, something
> >new for me. A few bands are dead, found 2 dead het. osc.
> >crystals- 12.395mc. The other - 22.895mc. Maybe I should go
> >look for Heath users group? I have a small box of xtals
> >accumilated over time, no luck. I think there is probably someone
> >out there who has these in their
> >good ie col lection? Please email me if you have these. thanks Russ.
>
--NextPart_Webmail_9m3u9jl4l_25488_1185278292_0-- ------------------------------ Message-Id: <7.0.1.0.2.20070724071751.02212d70@muohio.edu> Date: Tue, 24 Jul 2007 07:20:48 -0600 To: Old Tube Radios From: Jim Garland <4cx250b@muohio.edu> Subject: Capacitor Question Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed I"ve been repairing a DX-100 with a leaky grid-to-plate "postage stamp" mica capacitor. Reminded me of similar problems I've had with other rigs, including the KWM-1. Can someone tell my why so many radios used mica caps as grid-to-plate couplers, instead of ordinary disk ceramic caps? The mica caps are more expensive and I can't see the reason for them. Jim W8ZR ------------------------------ From: wb3fau@att.net To: Old Tube Radios Cc: Jim Garland <4cx250b@muohio.edu> Subject: Re: Capacitor Question Date: Tue, 24 Jul 2007 13:52:31 +0000 Message-Id: <072420071352.24732.46A6041F0004268D0000609C21612436469A0E00CC0D99@att.net> Postage stamp micas- why use them? At the time of mfg. of these radios, these were about the best, long lasting devices around. Also, in the case of Heath, they would buy stuff in bulk, and get a better discount. Remember how old these caps are? In my own repairs/renevation projects, often these caps are not failing until they are 60+ years old. We are often resurecting oldies that have not been powered up in years, a real bad thing for any capacitor. Russ. ------------------------------ Mime-Version: 1.0 Message-Id: Date: Tue, 24 Jul 2007 08:16:50 -0700 To: Old Tube Radios From: Scott Robinson Subject: Re: Capacitor Question Content-Type: text/plain; charset="us-ascii" ; format="flowed" Jim, Ceramic capacitors come in several types. The common ones are: NPO/COG--used for small capacitances only (less than 1000 pF?). These are great capacitors, temperature stable and quite linear. They don't have much capacitance for a given size X7R, Z5U, and all the rest: these are ONLY useable for bypass caps. They are fairly leaky, have a VERY large temperature coefficient of capacitance, and since their capacitance also varies with applied voltage, they make distortion (a few tenths of a percent, depending on how used) in audio circuits. They are used because they pack a lot of Farads into a small part. Micas are temperature stable and don't have funny losses. The only place I've found leaky ones is in my SX-42, so I guess you can get them in varying quality...but be warned, once in a blue moon I've seen one go open. Regards, Scott >I"ve been repairing a DX-100 with a leaky grid-to-plate "postage >stamp" mica capacitor. Reminded me of similar problems I've had >with other rigs, including the KWM-1. Can someone tell my why so >many radios used mica caps as grid-to-plate couplers, instead of >ordinary disk ceramic caps? The mica caps are more expensive and I >can't see the reason for them. > >Jim W8ZR ------------------------------ From: W6cds@aol.com Message-ID: Date: Tue, 24 Jul 2007 14:06:04 EDT Subject: Transformers for Collins PM-2 To: Old Tube Radios MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1185300364" -------------------------------1185300364 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit I have 2ea Collins PM-2 Transformers, Freed #40412 DSA900-73-M-CF36 and 2 ea Collins PM-2 Chokes, Ballastran BC-2951, 5950-008-6525 available. Anyone have any use for these? Charles Simmons w6cds ************************************** Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour -------------------------------1185300364 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * -------------------------------1185300364-- ------------------------------ Message-ID: <002701c7ce28$bcd3cf80$3c9f480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Capacitor Question Date: Tue, 24 Jul 2007 12:27:32 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > ... Can someone tell my why so many > radios used mica caps as grid-to-plate couplers, instead of ordinary > disk ceramic caps? .... The virtue of mica caps is they are free of dielectric eccentricities. Not so with ceramics. "Ordinary" ceramic caps will get you into trouble if used in place of mica caps. Unless you choose the correct type of ceramic capacitor you are in for two kinds of problems, capacitance drift with temperature and dielectric loss at high frequencies. You will only want to use in your DX-100 a ceramic capacitor with an NPO temperature characteristic and a high RF current rating. Mica dielectric is not inherently failure prone with age. It's the way mica capacitors are packaged. The capacitive "plates" are silvered areas on opposite sides of the mica. The only way to connect to the silver inexpensiviely is to place brass clips over the ends of the mica substrate. Over time due to moisture ingress the brass, copper, tin and silver mix of metals produce corrosion products that contaminate the interior of the molded plastic or dipped resin containment. Arden Allen KB6NAX ------------------------------ Message-Id: <7.0.1.0.2.20070724134449.022244a0@muohio.edu> Date: Tue, 24 Jul 2007 13:47:26 -0600 To: Old Tube Radios From: Jim Garland <4cx250b@muohio.edu> Subject: Re: Capacitor Question Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed > You will only want to >use in your DX-100 a ceramic capacitor with an NPO temperature >characteristic and a high RF current rating. > >Arden Allen >KB6NAX Good advice generally, Arden, but the capacitor in question is just a plate-to-grid coupling capacitor in the DX-100's audio preamp stage. I don't think temperature sensitivity, etc., matters a whit for that application. However, just so it would look stock, I replaced the original with a mica cap. 73, Jim W8ZR ------------------------------ Message-ID: <005101c7ce4a$1da9d680$6401a8c0@reloaded> From: "Al Parker" To: Old Tube Radios Cc: "Gumbear@Pacbell. Net" Subject: Re: Capacitor Question Date: Tue, 24 Jul 2007 19:26:51 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit Hi guys, I have seen, several times, micas in coupling applications fail in Hammarlund & Collins rcvrs, as well as in freq. determining applications in Hammarlund rcvrs. Generally they get leaky, sometimes they get "crackley", intermittent. Usually it's the small rectangular pink ones, can't remember their type designation. None of us here are talking about the usually brown "postage stamp" ones that are not mica, but papers in disguise. In the SP-600 rcvr, in later yrs, Hammarlund changed from paper "BBOD's" to disc ceramics in all aplications, e.g. bypass & coupling, except freq. determining, which were always mica. Good disscussion. 73, Al, W8UT New Bern, NC www.boatanchors.org www.hammarlund.info ----- Original Message ----- From: "Jim Garland" <4cx250b@muohio.edu> To: "Old Tube Radios" Sent: Tuesday, July 24, 2007 3:47 PM Subject: Re: Capacitor Question > >> You will only want to >>use in your DX-100 a ceramic capacitor with an NPO temperature >>characteristic and a high RF current rating. >> >>Arden Allen >>KB6NAX > > Good advice generally, Arden, but the capacitor in question is just a > plate-to-grid coupling capacitor in the DX-100's audio preamp stage. I > don't think temperature sensitivity, etc., matters a whit for that > application. However, just so it would look stock, I replaced the > original with a mica cap. > 73, > > Jim W8ZR ------------------------------ Message-ID: <002001c7ce52$a85b62f0$d09d480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Capacitor Question Date: Tue, 24 Jul 2007 17:27:52 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > Good advice generally, Arden, but the capacitor in question is just a > plate-to-grid coupling capacitor in the DX-100's audio preamp > stage. I don't think temperature sensitivity, etc., matters a whit > for that application. However, just so it would look stock, I > replaced the original with a mica cap. Jim, your original question contained, "..Can someone tell my why so many radios used mica caps as grid-to-plate couplers, instead of ordinary disk ceramic caps? .." You din't say it was in an audio amp, Jim. Gosh, any ol' crapacitor will do there. ;-) The answer is it was more economical to use micas when heaps of values were stocked for use at RF and IF frequencies. Cheaper than duplicating stock in ceramics. B4 the days of just-in-time material acquisition. So's my imgination tells me.... Arden Allen KB6NAX ------------------------------ From: "Thomas Frobase" To: Old Tube Radios Cc: Subject: Virus Alert http://www.kitparts.com Date: Tue, 24 Jul 2007 19:53:06 -0500 Message-ID: <030f01c7ce56$2b225c90$0c01010a@tfrobase1> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit After receiving John's alert yesterday I scanned my Linux based server with Apache web services and found no viruses, I downloaded all of the directories on the site to my local PC and scanned with Norton Semantic and Trend Micro virus tools, to which I entrust to protect the company I am employed by, and found no hits. My Son in law is a networking support person at the local high school who uses McAfee. I asked him to hit the site from the web and log the results, McAfee indicated a problem, but logged no errors once the initial hit was made. My site contains nothing but straight HTML, it is extremely simple. All I can credit is that there are anomalies in McAfee. Sorry for any inconvenience. If you still have concerns and are interested in Collins tools or rectifier replacements email me at N3LLL@kitparts.com Thomas L. Frobase, N3LLL League City TX 77573 ------------------------------ Message-ID: <007001c7ce5a$f6aeae50$640fa8c0@radioroom> From: "Tom Rauch" To: Old Tube Radios Subject: Re: Capacitor Question Date: Tue, 24 Jul 2007 21:27:19 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit > Good advice generally, Arden, but the capacitor in > question is just a plate-to-grid coupling capacitor in the > DX-100's audio preamp stage. I don't think temperature > sensitivity, etc., matters a whit for that application. > However, just so it would look stock, I replaced the > original with a mica cap. Jim, the same thing was done in some Viking and Collins rigs. Heath used the SM in many audio systems where they wanted low coupling capacitance. The reason they were silver micas was largely the value. . If you look at the values they were less than 1000pF, or .001mF in old-speak. Anything below .005mF was VERY uncommon in a ceramic disk. There were almost no low value ceramic caps available back then. There was an abundance of micas. Now I'm gonna push the hot button again. Here it goes..... I looked into the piezo effects of ceramic caps a few times over the past few years, largely because of claims they add significant audio distortion. Even the caps with the highest piezo effects only produce fractions of a millivolt distortion when the dielectric is twisted with a few dozen volts of change. The only place I can think of that happening to the extent it would affect a system would be in the frequency determining components of a low-distortion audio oscillator, or in a high-Q filter of some type where the cap is in a critical response shaping position. In all our good old boatanchors with 2% or more distortion and virtually no current through the caps from the high impedance systems, and hundreds of stable volts on the caps, I would bet money the distortion is immeasurable. It would take someone who can hear the difference between oxygen-free cotton covered matched impedance speaker wires and regular old zip cord on a HiFi system to hear the difference between a ceramic disk and a mylar in a radio. Or it might be that lady who bitched so much about her picture in her Muntz TV I rolled the vertical and told her to pick one she liked. She did, I left it there, and she was happy. Now I bet she could hear the difference. 73 Tom ------------------------------ End of BOATANCHORS Digest 4072 ******************************