20070721.ba v04_n071.bam.20070721 >From ???@??? Sat Jul 21 15:29:49 2007 -0500 Date: Sat, 21 Jul 2007 20:28:42 GMT From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4071 Message-Id: <20070721202845.AC07D47015B@srvr1.theporch.com> BOATANCHORS Digest 4071 Topics covered in this issue include: 1) Re: Battleship anchor question by "Morris Odell" 2) Re: Battleship anchor question by Dan Arney 3) Need DC/DC Converter Advice by "David's Mail" 4) Re: Need DC/DC Converter Advice by w1id@comcast.net 5) Re: Right angle banana plugs? by "Arden Allen" 6) Re: Need DC/DC Converter Advice by "Arden Allen" 7) Re: Need DC/DC Converter Advice by stuck in 50s 8) Re: Need DC/DC Converter Advice by "Tom Rauch" 9) Looking for a Specific Vibroplex Bug by "Gary H. Harmon, Jr" 10) Re: Need DC/DC Converter Advice by "David's Mail" 11) More Vodka-Scented Ether (long) by "David's Mail" 12) Re: [ARC5] More Vodka-Scented Ether (long) by "David's Mail" 13) R-390-A front panel by Raymond J Cote 14) Re: [Milsurplus] More Vodka-Scented Ether (long) by "David's Mail" 15) Re: [Milsurplus] More Vodka-Scented Ether (long) by "Arden Allen" 16) Eldico SBA-1? (Sideband adaptor) by john ---------------------------------------------------------------------- Message-ID: <001c01c7c90c$9205e980$ad00a8c0@Morris1> From: "Morris Odell" To: Old Tube Radios Subject: Re: Battleship anchor question Date: Wed, 18 Jul 2007 17:23:42 +1000 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit > nick@3rdtech.com writes: >> Having recently acquired a couple of these monsters myself, I am curious >> if >> anyone has info on the difference between the A models (WRR-2A/FRR-59A) >> and >> the B models (WRR-2B/FRR-59B). Evidently the B models were manufactured >> by >> Arvin rather than National. Anything else? On a closer look, mine is actually a "B", made by Arvin. Morris ------------------------------ Message-ID: <469DE423.4030304@pacbell.net> Date: Wed, 18 Jul 2007 04:57:55 -0500 From: Dan Arney MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: Battleship anchor question Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Morris, I think mine is a B also. How B U? Hank ------------------------------ Message-ID: <001601c7c957$f0725170$6401a8c0@boudreaux> From: "David's Mail" To: Old Tube Radios Subject: Need DC/DC Converter Advice Date: Wed, 18 Jul 2007 11:23:10 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit Those black monolythic block DC/DC converters you find on the surplus market these days- often 12 VDC to +/- 15 VDC or similar- work well but very RF noisy. I'm working with them for a BA project. If I enclose three in a metal box with heavy hash filtering in and out, will it get rid of most of the hash and birdies? Thanks. ------------------------------ From: w1id@comcast.net To: Old Tube Radios Cc: "David's Mail" Subject: Re: Need DC/DC Converter Advice Date: Wed, 18 Jul 2007 18:47:55 +0000 Message-Id: <071820071847.16428.469E605B000D32E10000402C22007637040B07CE99@comcast.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_16428_1184784475_0" --NextPart_Webmail_9m3u9jl4l_16428_1184784475_0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Modern DC/DC converters are very efficient due to the fact that they use a pulse width modulator which varies the duty cycle of a fixed frequency waveform according to the input voltage. Unfortunately, the asymmetrical waveforms thus produced are rich in both even and odd order harmonics. These harmonics extend from the fundamental and well up to the low VHF and sometimes even high VHF frequencies. Because the waveform is not generated from a precise source, it contains noticable jitter. When you say hash, you are really talking about 2 kinds of noise, conducted and emitted. The emitted noise can be reduced to a great extent if you enclose the circuit in a metal enclosure and observe proper grounding procedure. And therein lies the big question. Where do you ground the box in relation to the circuitry: where is/are the ground points? Also it makes a difference whether it is a steel or aluminum enclosure. Steel will be better for lower switching frequencies. Filtering will hel p elim inate conducted noise. You didn't say how much current those DC/DC converters will supply. Certainly, feedthrough capacitors will help as well as ferrite common mode filters. In my opinion, what you are contemplating doing is filled with pitfalls. The main thing will be how well the converters are designed. It follows that those which produce the least noise will also be the quietest due to the fact that unwanted radiation wastes power and lowers efficiency. Those would require much less filtering. However, that all depends on the manufacturer of the device and wheter they care about noise, or even efficiency. Usually they just care about cost: how cheap can they make those things and sell them before they fail in the field after the warrantee expires. Although I work in an industry involved in DC/DC converters at the chip level, I always avoid them like the plague in my own RF communications applications. Of course, if you have lots of time and patience, go ahead and experim ent. A fter all, this is what ham radio is all about. If you do, I hope you will share your findings with the rest of us. -------------- Original message -------------- From: "David's Mail" > Those black monolythic block DC/DC converters you find on > the surplus market these days- often 12 VDC to +/- 15 VDC or > similar- work well but very RF noisy. > I'm working with them for a BA project. > > If I enclose three in a metal box with heavy hash filtering > in and out, will it get rid of most of the hash and birdies? > > Thanks. > --NextPart_Webmail_9m3u9jl4l_16428_1184784475_0 Content-Type: text/html Content-Transfer-Encoding: 8bit
Modern DC/DC converters are very efficient due to the fact that they use a pulse width modulator which varies the duty cycle of a fixed frequency waveform according to the input voltage. Unfortunately, the asymmetrical waveforms thus produced are rich in both even and odd order harmonics. These harmonics extend from the fundamental and well up to the low VHF and sometimes even high VHF frequencies. Because the waveform is not generated from a precise source, it contains noticable jitter. When you say hash, you are really talking about 2 kinds of noise, conducted and emitted. The emitted noise can be reduced to a great extent if you enclose the circuit in a metal enclosure and observe proper grounding procedure. And therein lies the big question. Where do you ground the box in relation to the circuitry: where is/are the ground points? Also it makes a difference whether it is a steel or aluminum enclosure. Steel will be better for lower switching frequencies. Filterin g will help eliminate conducted noise. You didn't say how much current those DC/DC converters will supply. Certainly, feedthrough capacitors will help as well as ferrite common mode filters. In my opinion, what you are contemplating doing is filled with pitfalls. The main thing will be how well the converters are designed. It follows that those which produce the least noise will also be the quietest due to the fact that unwanted radiation wastes power and lowers efficiency. Those would require much less filtering. However, that all depends on the manufacturer of the device and wheter they care about noise, or even efficiency. Usually they just care about cost: how cheap can they make those things and sell them before they fail in the field after the warrantee expires. Although I work in an industry involved in DC/DC converters at the chip level, I always avoid them like the plague in my own RF communications applications. Of course, if you have lots of time and patience, go ah ead an d experiment. After all, this is what ham radio is all about. If you do, I hope you will share your findings with the rest of us.
 
-------------- Original message --------------
From: "David's Mail" <arc5@ix.netcom.com>

> Those black monolythic block DC/DC converters you find on
> the surplus market these days- often 12 VDC to +/- 15 VDC or
> similar- work well but very RF noisy.
> I'm working with them for a BA project.
>
> If I enclose three in a metal box with heavy hash filtering
> in and out, will it get rid of most of the hash and birdies?
>
> Thanks.
>
--NextPart_Webmail_9m3u9jl4l_16428_1184784475_0-- ------------------------------ Message-ID: <003b01c7c97a$4be265f0$47a1480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Right angle banana plugs? Date: Wed, 18 Jul 2007 13:28:50 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > ......The test leads on my Triplett 666-R VOM (that I bought new in 1982) have finally failed ..... Probemaster might have what you want: http://www.probemaster.com/testlead8000.htm Just cut off the safety shroud on the right angle banana plugs. Arden Allen KB6NAX ------------------------------ Message-ID: <006a01c7c97c$d35a59f0$47a1480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: Need DC/DC Converter Advice Date: Wed, 18 Jul 2007 13:47:04 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > If I enclose three in a metal box with heavy hash filtering > in and out, will it get rid of most of the hash and birdies? The easy answer is to find older analog power bricks, no birdies singing in the trees. The trick to eliminating the noise from the switchers is to use salvaged line input filters (bypass caps and common mode chokes) from computer power supplies. Any computer store is likely to have dead power supplys in the back room if you don't have any in your own pile. Use good RF construction techniques (short leads to a ground plane) to get effective filtering. You may also want to get better HF filtering by constructing common mode chokes on tubular ferrite cores, like the one on your computer monitor cable. Two or three ceramic caps in parallel, like 470pF, .01uF and .1uF at each node will avoid series resonance problems. Short leads, short leads, short leads...... Arden Allen KB6NAX ------------------------------ Date: Wed, 18 Jul 2007 16:49:17 -0400 (EDT) From: stuck in 50s Message-Id: <200707182049.l6IKnHdt008778@fracas.netboobie.org> To: Old Tube Radios Cc: arc5@ix.netcom.com Subject: Re: Need DC/DC Converter Advice OK, I'll chime in on this > .....go ahead and experiment. A fter all, this is what ham radio is all about. If you do, I hope you will share your findings with the rest of us. I've run both a BC-1000 and an RT70 on a 12V gel cell & a ciggy lighter 35w 12VDC -> 115VAC 35W drug store blister-pack inverter. Bridge rectify 115VAC into choke input filter fer ~90vdc B+ 4.5vdc for BC 1000 fm 5VDC wall wart seriesed w. Shotky Barrier diode 6VDC for RT70 from different wall wart(s) Works fb but pse note - both rigs are FM. Pix of both embodiments on Ray Fantini's 2006 & 2007 Dayton website. And a closing note. My BC-1000 was all broken. Every 'coronet' postage-stamp paper bad, real bad. But the RT70 only had two bum tubes plus a tricky mechanical. Basically, however, the electronics were plug 'n play & hope that'll bring some out of woodsheds. One more RT70 note is the AM-65 audio amp / vibrapac kennel. Try an LS-124 with a 12vdc computer speaker amp module hidden inside. U can get audio drive on the power connector. Or just paint the computer speaker. Then with apollogies to some, Walter Mitty, pretend you're using 6m to take Porkchop Hill Marty ------------------------------ Message-ID: <05b801c7c98c$4285fc30$640fa8c0@radioroom> From: "Tom Rauch" To: Old Tube Radios Subject: Re: Need DC/DC Converter Advice Date: Wed, 18 Jul 2007 18:35:53 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit > Those black monolythic block DC/DC converters you find on > the surplus market these days- often 12 VDC to +/- 15 VDC > or similar- work well but very RF noisy. I'm working with > them for a BA project. > > If I enclose three in a metal box with heavy hash > filtering > in and out, will it get rid of most of the hash and > birdies? David, Put M. Faraday and the gang to work for you. Get a hunk of double sided PC board material and make a seamless box. Easy to work with. Put the regulators inside the box, and use feedthrough caps of some reasonable value (like 1000 pF or more). Decoupling choke or multiturn beads go inside the box. You can tack some .33uF or larger multilayer caps with short leads between the feedthroughs and the box walls inside the box. You could even use a little pi section filter on each lead inside the box if you are careful to have the pi resonant far below the lowest frequency that can bother you. (A pi filter can hurt decoupling if it acts like a matching network on some frequencies. When you do that, and if you seal all the edges with solder, you can easily get well over 100dB isolation from a few hundred kHz to UHF. That little PC board box you hold in your hand can be tucked almost anywhere, and lead lengths or grounding won't be critical at all. Think of it as an oscillator, sensitive audio amp, or attenuator that you want to shield... and treat it that way. It works exactly the same. Even very low frequencies won't be an issue. Check out this link: http://www.w8ji.com/skindepth.htm 73 Tom ------------------------------ From: "Gary H. Harmon, Jr" To: Old Tube Radios Subject: Looking for a Specific Vibroplex Bug Date: Thu, 19 Jul 2007 14:16:56 -0500 Message-ID: <004401c7ca39$5f657620$4a01a8c0@garyh4i1k3x2lw> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0045_01C7CA0F.768F6E20" This is a multi-part message in MIME format. ------=_NextPart_000_0045_01C7CA0F.768F6E20 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I know it's a long shot but......A good local friend of mine was asking me this morning about a bug to go with his Harvey Wells equipment. He mentioned he had his grandfather's sounder, hand key and pocket watch but not the bug. It's a Vibroplex with a chrome base and has "Buck" engraved in the base. If anyone has this bug and would like to sell or trade it for another bug please let me know. Thanks in advance and 73, gary Gary H. Harmon, Jr. / K5JWK 6003 Archwood San Antonio, TX 78239-1504 210.657.1549 - home / 210.884.6926 - cell "Retirement means everyday is a Saturday, except Sunday" ------=_NextPart_000_0045_01C7CA0F.768F6E20 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ------=_NextPart_000_0045_01C7CA0F.768F6E20-- ------------------------------ Message-ID: <000601c7cace$f8679480$6401a8c0@boudreaux> From: "David's Mail" To: Old Tube Radios Subject: Re: Need DC/DC Converter Advice Date: Fri, 20 Jul 2007 08:07:43 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit Thanks, everyone, for the good advice. I decided to go ahead with less sheilding for the "trial" of the concept, and put up with a few more "birdies" for now- " no free lunch," as they say. I'll write everything up soon as work allows. I'm pleased with how it's worked out. I now have a receiver with eight 6-volt fil. tubes that sounds great and runs on 12 VDC at about 1.4 amps. Thanks again. 73 D.S. ------------------------------ Message-ID: <004901c7cb27$ffd09010$6401a8c0@boudreaux> From: "David's Mail" To: Old Tube Radios Subject: More Vodka-Scented Ether (long) Date: Fri, 20 Jul 2007 18:45:02 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=original Content-Transfer-Encoding: 8bit Vodka Scented Ether Or The Continuing Saga of The Low B+ Russian Radio "УC-П" (pronounced "oo-ess-'pay") http://home.netcom.com/~arc5/usp/2.jpg I'm really enjoying the challenge of getting this old "Red" radio perking again. Here's a photo of it paired with Soviet transmitter "RSB-F" in radio set "RSB." I probably wouldn't trade one of my daughters for an RSB-F..... probably... : http://home.wxs.nl/~meuls003/gallery/usp.html In my early collecting years, before I knew better, I "recapped" an authenticaly rare set, thereby ruining the fine workmanship under the chassis. I have since resolved never again to be guilty of that, but I still wish to operate my radios once in awhile. I have, therefore, been working on ways to operate my radios without resorting to mass cap and resistor changes. While I'm still learning every time I heat up my iron, I'm guided by these principles: + Make no change that is not 100% restorable to the original configuration. + Do as little as possible. + Do not expect a "Model "T"" to be a Porsche; enjoy your Model "T" or give it to someone who will. + Preservation trumps performance. I've found that the large majority of old caps which fail at their rated voltage will still perform their function in an acceptable manner at a much reduced voltage, and that when a stage is running at a fraction of the intended B+, resistors far out of spec don't seem to matter much. There are no "free lunches," of course; I am willing to accept some trade-offs in performance to both keep the receiver as near "stock" as possible and still enjoy operating it. In most cases, the trade-offs have been, IMHO, minor. The underchassis of the УC-П is pretty cool, so I determined I was not going to "gunch it up." http://home.netcom.com/~arc5/usp/4a.JPG WF2U kindly sent me the manual for the Russian УC-П receiver- Thanks a million, Meir! He also pointed-out the reason for the radio being “deaf “ on AM: the detector is biased heavily off, which provides a crude sort of “squelch,” giving the Russian pilot’s ears a rest until someone close by transmits. Moving the pin-8 ( cathode two ) connection of the dual-diode detector to ground gives normal sensitivity. Although, to an English speaker, the detector tube appears to be marked "6X6," the "X" is actually the Russian letter "Khah" (pronounced "ha"), and is the closest thing in their alphabet to an English "H." The tube is a equivalent to a 6H6G. The tube filaments had been wired for 6 volts when I got the set, but the manual calls for 12 or 24 volts. I decided to restore the wiring to the 12-volt state. I purchased some monolithic block DC-to-DC converters at a local surplus outlet for $4.95 each, which included the circuit board mounts and a couple of filter caps. http://home.netcom.com/~arc5/usp/3a.JPG The converter inputs were speced at 9-18 VDC with plus-and-minus 15 VDC at 1 Amp outputs. The boards included a little trimmer resistor used to adjust the output voltages. At zero resistance, the outputs were 13 volts. At infinity, they were 15.2 volts. By connecting to the + and – outputs and ignoring the center common point, I got a floating 26 to 30 volts. I connected two of these outputs in series for 60 volts- plenty to run a low B+ receiver. I tried three for 90 volts, but it was too stressing on the aged components and didn't enhance performance much. The only problem with going down to 60 volts was that, over a small portion of the dial scale at the most "full mesh" of the tuning cap, the local oscillator quit. Everything else worked fine. This aren't important spectrum to me, being neither ham nor SWL band, and it isn't worth the extra strain to get that little bit, so I let it go. Digging around in my junk produced an old “Archer” Radio Shack transistorized audio amp that runs on 6-9 volts. You probably remember these little hi-Z input project amps, which came in several power levels. They are very handy and I always grab any I find in a hamfest box. A little 5-volt regulator dropped the 12 volts to 5 for the audio amp. I tinkered this all together with utterly inadequate RFI suppression. Here's my messy "prototype:" http://home.netcom.com/~arc5/usp/pwr.JPG Even so, some .01 and .1 caps on the input and output leads, plus some ferrite beads killed 99% of the switching hash and most of the "birdies," leaving a few attenuated ones here and there. Grounding the power chassis direct to the receiver attenuated them more. Once I got it perking, a proper alignment really brought it to life. With a 112 KC IF, you can't play "good enough" with alignment. A good sig gen, freq standard and scope and the proper procedure are required if you want to keep the images down. It's a "touchy" set to align. The dial calibration does not track especially well and there are no trimmer caps on the LO side to make it track; only the LO coils. I got it to track reasonably well over 160, 80 and 40 meters and decided to accept that, rather than risk damage in an attempt to "make a Porsche from a Model T." I've been running the set on my bedstand for several days, letting it run overnight to see if the supply is going to hold up. So far, so good. The set sounds great with all the audio I can stand. In fact, the input to the little Archer amp is swamped with a 4.7 K resistor to ground and a 2.2 meg in series to keep the level from the radio down. The morning AM crowd sound as good as they do on any of my receivers (but then, I'm half deaf ;-). One of the "trade-offs" of low B+ is that the AGC doesn't really work much. I'll accept that; "preservation trumps performance." http://home.netcom.com/~arc5/usp/5a.JPG The only problem that's developed is some background "crackle" noise when I turn on the BFO, which is probably either a cap in the BFO circuit that is too far gone even for low B+ or the Russian BFO 6K7. I'll put a scope on it this weekend and find it. Oddly, the longer the converters run, the less pesky the birdies. The peak 12-volt current draw with the set playing wide-open is about 1.8 amps, close as I can measure. Averages about 1.2 amps. Total 60 volt B+ current at full output is about 14 milliAmps, averaging 10 mA. Not bad for an eight-tube radio. You could run this thing on a car battery for a long time. Who knows? Maybe Boatanchor Field Day, Battery Class one of these days. I just found some surplus AT&T converters which are less than half the size. I'm going to build the "neat" version with them and let you know how it comes out. There is one other problem: "David! Must you listen to that noise all night long??" Women; they'll never understand radio.... 73 Dave AB5S. ------------------------------ Message-ID: <006101c7cb29$5a385f50$6401a8c0@boudreaux> From: "David's Mail" To: Old Tube Radios Subject: Re: [ARC5] More Vodka-Scented Ether (long) Date: Fri, 20 Jul 2007 18:54:43 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=response Content-Transfer-Encoding: 7bit P.S. One caution I meant to put in the post: These DC/DC converters are capable of high current output. Three in a row will supply 90 volts at ONE AMP. That's enough to cook your goose. Put even more of them in series and you could sizzle in your own juices for a long time. 60 volts can still hurt you, though it's less likely to be fatal. Don't take it for granted. Be careful. 73 Dave Stinson AB5S ------------------------------ Message-ID: <46A16A79.7080107@hawaii.rr.com> Date: Fri, 20 Jul 2007 16:07:53 -1000 From: Raymond J Cote MIME-Version: 1.0 To: Old Tube Radios Subject: R-390-A front panel Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Hey Guys, a while back (quite a while back) I had borrowed a bare R-390 A front panel from someone on this list with the intention of machining new ones on a Hurco computer controlled mill. That fell through after many tries. I need to get it back to the rightful owner but lost my hard drive and cannot remember his name. He has been VERY patient in contacting me and need him (you) to e-mai me with your name and address so I can ship it back to you. Thanks in advance Ray Cote Honolulu ------------------------------ Message-ID: <003801c7cb97$d9cb0650$6401a8c0@boudreaux> From: "David's Mail" To: Old Tube Radios Subject: Re: [Milsurplus] More Vodka-Scented Ether (long) Date: Sat, 21 Jul 2007 08:05:38 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="windows-1250"; reply-type=original Content-Transfer-Encoding: 7bit Original Message ----- From: "Meir WF2U" > Regarding caps in Russian equipment - I never had a bad cap (excluding > electrolytics) in any Russian equipment I own, and never had a cap failing > at the rated supply voltage. Their caps are constructed using a different > technology that is not prone to deteriorate and short out.... > Feeding the US-P with 150-160 V should be safe, even if you don't want to > apply the full rated 200V. Thank you for writing, Meir, and for sharing your superior knowledge of these radios. I'm confident you're correct about the caps. The higher voltage would likely work, but it isn't needed to make the receiver perform in a manner I find acceptable. I believe I lose a minor amount of performance, but gain better preservation by using as little B+ as possible. Moreover- it's safer for me, because I'm clumsy. My fingers keep forgetting that electrons hurt. I've already been "bitten" by the 60 volts once. Had I been running 200 volts, it might have been nasty. >.... Also, the tube socket contacts are > intermittent sometimes (contact material quality) and ground rivets/srews > should be checked for good ground contact. I forgot to mention in the post that I did find two grounding screws and nuts which had come loose- one in the tuning cap, one that provided ground to the interesting mounting strip along the "audio" side of the rig. I'll check for more. And thanks for the tip on the resistors. If I find a bad component, I'll lift one end, leaving it in place and "tack-solder" in a replacement. Another thing I forgot to include: The audio output is derived using an audio choke with a cap coming off a center-tap. the half between the output cap and the audio tube is open. I tacked-in a 3300 ohm resistor across the open winding and that restored function. 73 Dave S. ------------------------------ Message-ID: <002801c7cbd2$97a8a0d0$2f9e480c@KB6NAX> From: "Arden Allen" To: Old Tube Radios Subject: Re: [Milsurplus] More Vodka-Scented Ether (long) Date: Sat, 21 Jul 2007 13:06:06 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1250" Content-Transfer-Encoding: 7bit >...... + Make no change that is not 100% restorable to the original configuration. + Do as little as possible. + Do not expect a "Model "T"" to be a Porsche; enjoy your Model "T" or give it to someone who will. + Preservation trumps performance. ....... I agree, David, those are good rules to guide you, especially if a rig is extremely rare and all original. IF, however, you do need to replace a component in order to obtain proper operation, make your workmanship match that of the original. Also, the failed parts can be removed in such a way as to make it possible to reinstall them in case a future owner wants to have a display unit in total originality. It takes some careful planning on how to do each part but the satisfaction eventually outweighs the frustration. I myself prefer total restoration, i.e., restore its orginal performance because that's part of the experience of historic radio. I would operate the radio at full B+ being careful not to cause any additional mayhem. Just making sure the model T is firing on all four (need to be able to at least back-up hill).... Arden Allen KB6NAX ------------------------------ Message-Id: <6.2.1.2.2.20070721162733.03d47e20@pop-server.nc.rr.com> Date: Sat, 21 Jul 2007 16:28:58 -0400 To: Old Tube Radios From: john Subject: Eldico SBA-1? (Sideband adaptor) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Picked one of these up off the bay...anyone familiar with them? They're painted to match the Eldico MIL SSB transmitter. Cant find much info on the web....anyone familiar with it? It's in a 19" rack panel. 73 John K5MO ------------------------------ End of BOATANCHORS Digest 4071 ******************************