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The Tram Diamond is a classic valve powered transceiver that has excellent specifications and reflects this in its rich full audio receive tones and superlative transmitted studio sounding output audio.

 
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CPI - Communications Power International

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TRAM Diamond Corporation

  The Tram D201 was considered one of the best valve powered Citizens Band Transceivers.

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A supreme top of the line radio from the Tram/Diamond corporation.


 

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This page was last updated on 26-Oct-2010 19:42.

 
TRAM DIAMOND D201
 

The Tram Diamond is a classic valve powered transceiver that has excellent specifications and reflects this in its rich full audio receive tones and superlative transmitted studio sounding output audio.

As much as I would like to talk knowledgeably about the classic Valve powered CB Radio, the Tram Diamond D201, I really could not do the radio justice, hence the story below from Dave Hall N3CVJ.

I had always wanted one since they were released in the USA in the early days of CB operation on the government allocated 23 Channels in the 11 Metre Band at the bottom of 27MHz. Best I could do back then, was the first Courier Gladiator 40Ch PLL in Aust.
Many radios followed, but my favorite was always the CPI - Communications Power Inc. CP2000 40CH Base & Console Freq counter.

When about mid 2007 I was alerted to another radio on Ebay by a friend who knew I wanted a better UHF 477MHz CB, but spotted the TRAM D201 going for about $100 USD!

In the end after bidding on it, and getting it for about $170 USD, I had it delivered to my home in Melbourne Australia for the all up cost of nearly $500 AUD!! - More than I paid for ANY CPI!!

BUT, it was worth it to me, as it was in fantastic condition and come complete with original microphone and complete original service manual with schematics! Although it was 110VAC input it did not concern me because I always have had 110 to 240 VAC transformers around being a mobile Micrographics tech for a US company - Bell & Howell. (Origin of my callsign - The BellHopper )

After firing it up and realising it was only 23 Channels Xtal Locked, I was a bit dismayed as I had thought it was 40 Ch and had an 02A PLL for frequency selection. I had confused it with a later model!

Although the disappointment faded when I realised it could RX tune to 27,500 on the Manual Tuning VFO and could be modded to TX as well. Looks like the RATHOLE and CH#35 are well covered!

After it settled down and got a bit warmer, I found it was receiving LSB on the USB setting but it was listening like my CPI CP2000 but maybe even BETTER! The sound of the audio which can be adjusted for tone on RX as well as TX was warm and clear and the QRN seemed much less than usual.
Maybe just conditions but we will see after I have it tuned up and the RX Mode fixed along with any valves that may need to be replaced to bring it back to its former glory.

 

 c

 

 

 

The following information was copied from Dave Halls site below.

http://home.ptd.net/~n3cvj/cbpage.htm  By Dave Hall

In my defense I sincerely apologize, but put the case forward of so many great stories in a similar vein that have been lost to the vagaries of time and forgotten website renewals.

It would be criminal if this valuable information on the rescue of a few of these great classic TRAM D201 CB's were lost to the ether and unavailable for the education of the greater Citizens Band community.

Please follow Dave's Hyperlinked text in the stories to more information as it is well worthwhile.

And Dave, if your listening and really want me to remove this, please just ask and I will save it for my consumption only!

 

 By Dave Hall  http://home.ptd.net/~n3cvj

This is the Tram D-201/201A, A supreme top of the line radio from the Tram/Diamond corporation. Where the Browning Golden Eagle was considered the "Cadillac" of CB radios, the Tram D201 was the "Lincoln Town Car".  This radio was truly at the top of the CB line, and had a price tag to match. At a retail price of over $750 in 1970's dollars, this was not the rig for most people, especially those of us living on paper route money. The D201 was a 23 channel radio, while the D201A was the 40 channel version.  Other than number of channels, they were virtually identical in appearance and features. The original D201 was first made in the early 70's and used primarily tubes, although some oscillator circuits were solid state. The D201 came loaded with many features.  Besides the usual standard features of  Volume, Squelch, Channel selection, Clarifier, Mode selector, and R.F Gain & Mic Gain controls, this radio also included a built-in SWR function with calibration control, and an adjustable noise limiter.  An interesting and innovative feature was the inclusion of not only a receiver tone control, but also a separate transmit tone control which allowed the careful tailoring of the audio characteristics of the radio to match practically any mike.  Also included was a continuously variable manual receiver tuner.  The range of the manual tuner extended beyond the normal legal channels and allowed for some interesting operator options including split frequency operation.  Rounding out the list of features includes a large easy to read S/RF/SWR meter, a modulation indicator light and a receiver spot.  Some versions of the D201 also came with a VOX which allowed "hands free" talking. The radio originally shipped with an un-amplified Astatic D-104 which mated well with the radio.

Performance-wise, this radio really shined. Transmit audio was, in a word, awesome. It had that warm "tube sound" that just couldn't be duplicated or beat by common transistorized radios. The receiver performance was also exceptional as it had both great sensitivity and adjacent channel rejection as well.  The D201A was also probably the only 40 channel radio, that I'm aware of, that still used straight crystal synthesis, over a PLL circuit.  A common modification involved converting the manual tuner to also operate the transmitter, allowing for synchronized "sliding" similar to that found with an external  VFO.  There were many other modifications that could be applied as well.  Besides the aforementioned VFO mod, there were also mods for power, and the clarifier. 

Because of the high price that this radio commanded, there naturally were very few in my local area. Storm Queen was rumored to have had one shortly before her departure from the radio scene. Dennis (not Dennis the Menace) also had one.

A mint condition D201 still commands a premium price on the collector's circuit.  Someday, I'm hopeful that I'll be in the right place at the right time and can pick a decent one up to add to my collection. That "Someday" occurred recently with the acquisition of two "needy" D201's from E-Bay. Read about my restoration project here.

  I Had a Dream........         By Dave Hall  http://home.ptd.net/~n3cvj

The story of the Good, the Bad, and the Ugly.   

 Back in the 1970's, when my friends and I first started out in CB radio, we didn't have a lot of money to spend on equipment, so most of us worked our way slowly and (sometimes) painfully up from 100 mW Walkie-Talkies, to 1 watt (or more) Walkie-Talkies, to very modest 23 channel AM mobile rigs,  and then eventually to a SSB rig, in various steps over a few years time.  During that time period, we would peruse the various radio supply catalogs and admire those fancy, expensive rigs that everyone dreamed about owning, but didn't stand a snowball's chance in hell of affording back then.  The Lafayette Telsat SSB-25, SBE Console II, Cobra 135, Pierce Simpson Simba, Hy-Gain 623 and others were my most common dream rigs.  At the top of pretty much everyone's dream list though, were the Browning Golden Eagle, and the Tram D201.  Both of these rigs were at the top of the premium rig list, and had price tags which were twice what most other full-featured, dream-worthy rigs had.  The fact that most of us would never see rigs like this only made them all that much more irresistible and attractive.  It's an unfortunate fact of human nature that the more you can't have something, the more you seem to want it.  Well, time marched forward, as it invariably does, and I've gone through quite a few different radios in my time, including some decent performing (and equally expensive) ham rigs like a Yaesu FT-101EFT-757GX, and Icom 706. And with such radios, the desire to obtain one of those early dream rigs faded in the process.  However, now that those 30 long years have gone by, and I'm waxing nostalgic, and revisiting those old classic CB rigs, I find myself about to realize one of my childhood dreams, as a once top-of-the-line Tram D201 is about to fall into my hands.  But like many of life's other pleasures, this one also comes with a catch - it needs some (maybe a lot of) work to bring it back to its former glory. This should really come as no surprise as any electronic device, which survives a 30 year service life, is going to incur a few battle scars along the way.  Adding to the problem are modifications performed by those screwdriver "technicians", who often ignore good engineering practice in the quest to make their rigs "louder", "stronger", and more frequency agile.  Many of those mods can be detrimental to the life expectancy of the rig itself.  So while I'm excited to finally operate something I once could only dream about, I'm also realistic (no not Radio Shack!) about the very real possibility that the rig may never perform as well as it once did when new.

The realization of my long time dream came about totally unexpectedly though.  I had started playing around with the old classic rigs that I had sitting in my closet, just for fun, and started extolling the nostalgic appeal of those old vintage tube rigs to the locals on the channel. The next thing I knew, at least 2 other people had started buying up old classic rigs from E-Bay.  Art especially, had gone totally outer limits buying up Sonar, and Robyn tube rigs, including a hybridized 40 channel version, and even some not-so-classic solid state rigs.  But during his buying frenzy, he somehow bid on (and won) a Tram D201 by mistake (He thought it was an even older Tram Titan), which needed work.  He then found another D201 to use for parts.  But the original rig turned out to be in worse shape than the supposed "parts" rig and neither rig is in operating condition.  He soon found himself overwhelmed by the complexity of the Tram's circuitry.  So now I get to put my talents to work in trying to get at least one of these wonderful old monsters working again.  Me, being the radio optimist that I am, am not yet ready to condemn the "parts"  radio completely and I will try to get that one working as well.  But it's missing some key parts, and I'll have to find yet another parts radio (Which I'll also probably want to restore, so the cycle will never end....) or jury-rig some aftermarket parts to make them fit. 

I was recently at Art's house to help him with a boat project and while there, I picked up the two restoration candidates, which I nicknamed "Bad" and "Ugly". These names came from an inspiration I got the the other night, when some skip-talking redneck bonehead kept playing his overmodulated noise-toy over and over, playing the theme from the movie: "The Good the Bad and the Ugly", which was annoying in itself, and forced me to run the squelch control a bit higher than normal.  But like they say, every cloud has a silver lining, since it gave me the inspiration for the name of this project.  The goal therefore, is that I will be able to garnish one "Good" radio from the combination of the "Bad" and the "Ugly".

First let's start by introducing the 2 rigs:

"Bad", was in somewhat decent physical shape, a few scratches were the extent of its exterior defects.  It was sold by someone who was in the process of restoring it, but claimed he had lost interest.  There were a few tubes, the relay, and some panel lights missing, and the power transformer looked as though it had caught fire on the bottom, as the insulation looked burned.

 

 

 

"Ugly" was in a little rougher physical condition.  The top cover had a square hole cut in the top presumably to accommodate a cooling fan (I cringe at the mental picture of some yahoo taking a sawz-all to the top of this classic rig) and there was a chunk broken off of one of the woodgrained sides.  It contained a fairly complete set of parts, but some of the circuit boards were blackened, circuits traces lifted, solder connections showing dull and overheated connections from excessive current draw (a result of someone's attempt at a power mod no doubt), as well as many band-aid repairs and modifications which had been performed over time trying to keep the rig alive.  "Ugly's" power transformer had similar issues with a burned insulation wrapper, as it is now completely missing on the bottom, exposing the windings.  When the Art powered up this rig, his room lights dimmed, and he quickly turned it off. It would appear that something major is shorted.  Hopefully it's not the power transformer......

 

Art had taken the relay and some of the other parts from "Ugly" and transplanted them into "Bad", and when he powered that rig up, he thought he had some semblance of receive, but little else.  So that's where I now stand.  I will resist the temptation to immediately power up the rig, and instead work to clean up the boards, poor connections, switch contacts, and undoing poorly done modifications first.  I began my anxious and equally daunting task by blowing the insides out with a blast of compressed air, followed by a manual dusting and spraying with circuit board cleaner. I also printed out the service manual and schematic for the radio, and started to familiarize myself with this unique hybrid circuitry.  It would appear that there were a few revisions in these D201 radios during their history, and even my two rigs are different in subtle ways.  "Bad" has a 3 pin grounded A.C. plug, while "Ugly's" plug is only a 2 pin. Adding to the confusion, the D201 schematic that I have, dated 1975, appears to be for the original point-point hand wired version, as it does not show the boundaries and connections of the various circuit boards. The D201A (40 channel) version, does show the board divisions, and is otherwise electrically similar.  So I'll have to rely on both schematics to muddle my way through this mess.

The next day was spent cleaning up the low voltage regulator board (called the "Aux audio" or "BA" board). There were several fractured solder connections on the Molex plug, as well as blackened resistors and a tacked-on replacement capacitor.  I replaced the questionable parts and repaired the solder connections. I also pulled out the other plug-in board and retouched the solder connections there as well. I also sprayed more cleaner on the PCB's and went to town repairing lifted circuit traces, and questionable solder connections.  I also spent some time looking at "Ugly". I determined that there is a short in the HV power supply, which would explain the large current draw that Art saw when he plugged it in.  While it seems more likely that I'll be able to restore "Bad", and may have to take some parts from "Ugly" to complete the task, I am still hopeful that I can get both rigs working at some point.

Day 3 started with me making some further checks of connections, but I wasn't able to continue on this path for long before I succumbed to my overwhelming desire to just fire it up and see what happens.  So I placed the radio on my work table and plugged it in. Turning it on saw the panel lamps light as well as the tube filaments. So far no smoke, and after a few more seconds, I started hearing an A.C. hum from the speaker (at least I have audio). Keying another radio on the same channel, saw the S meter move and some feedback erupted from the speaker of the Tram.  Great!, I thought, the receiver's working. But as I would find out, this project would not bring me satisfaction without a fight.  I tested the power supply voltages and they were all present and within range, except for the 270V supply which was running well over 300V.  So far, so good. The S meter was acting somewhat erratic and there was some intermittent static in the receiver along with it.  Hooking up the signal generator showed that while the receiver was technically "working", it was not very sensitive, as I had to put in about 200uV worth of signal to get anything.  Lack of background noise leads me to believe that one of the later I.F. stages or the detector may have a problem. To add to the growing list of issues, the manual tuner does not appear to be working either.  But the worst problem turned out to be SSB receive, or should I say "no receive", as in it's completely dead.  I tried a quick alignment, and that improved AM receive slightly, but it's still way down, and still nothing on SSB. I also swapped a couple of tubes with parts from "Ugly". I also swapped out the balanced modulator board as well (since it was plug-in). But so far, nothing helped the SSB receive.  I haven't wired the mike plug yet, so I didn't try the transmitter, but I did set the final bias. I plan on trying the transmitter the next time, as it will help me isolate other problems. If SSB transmits ok, that reduces my suspect list as parts of the SSB IF are shared by both transmit and receive. I can also check to see if the manual tuner works on transmit (another popular mod), which can further shed light on this problem. I will also focus on the mode and tuner switches and the relay, and how the various voltages are switched depending on the mode it is in. The problems I'm having could be caused by something as simple as a missing voltage due to a dirty (or mis-wired) switch. I'm also going to check ripple voltages on the supplies and replace any filter caps, if needed.

The next night, I wired up the mic plug and decided to see how the transmit side of "Bad" was working.   Surprisingly, the rig transmitted a strong 4 watt carrier on AM, with modulation.  Switching the crystal/manual switch to the manual mode did not change the transmit frequency, which tells me the that VFO transmit mod had not been performed (or, as I would later find, not correctly).  It also transmitted on SSB, although it appeared to be distorted or the crystal oscillator was off frequency. The AM modulation envelope was also somewhat strange and distorted looking. Attempts to neutralize the final to remove the spurious emissions were met with failure, although I was not able to perform the process per the alignment procedure, so when I revisit the transmitter later, I'll make a more comprehensive attempt. Operating the transmitter was done mostly to determine if the cause of the SSB receive problems could be traced to the Balanced Modulator board. Since the transmit and receive share components here, the fact that SSB transmit worked, pretty much eliminated this component as the root cause of the receive problem. I then decided to visit the audio hum issue. Interestingly, when the rig is first powered on, as the receiver is first warming up, the audio is crystal clear, then the hum pops in and is sometime intermittent. The usual initial suspect in a case like this, is a power supply filter cap. The voltages were checked for excessive ripple, and where there was a little more ripple than what I thought it should have, I tacked another cap across it to reduce the ripple. After the supplies were corrected, the hum was still present.  Probing the audio output tube socket with the scope showed a fairly strong A.C. component on the cathode and plate. I am now wondering if my BRAND NEW 6L6 tube has a heater-cathode short, which is coupling the A.C. filament voltage onto the cathode......

Recap of "Bad's" remaining issues:

AM receiver working but weak.

SSB receiver dead.

Manual tuner dead.

Hum on receive audio.

AM TX there, but modulation distorted (Possibly related to the hum problem).

SSB TX is also working, but in need of an alignment.

 

Day 5 was a banner day for forward progress on the problems plaguing "Bad".  I had decided to concentrate my efforts to resolving the receiver hum problem.  I had at first thought that there might be a tube short coupling A.C. filament voltage onto the cathode of the audio output tube.  But as I progressed down this path, I was able to determine that the hum was not being introduced in the final section.  I traced the problem back as far as the volume control.  A clue came when the transmitter was energized and the hum went away.  Another clue was that the hum went away when the squelch was advanced.  Swapping every tube in the audio chain did not resolve the problem.  Becoming frustrated, I decided to take a different path and look into the weak AM receive.  I noticed that the R.F. front end tuning was not very responsive, so I swapped out the 6BQ7 front end tube with the one from "Ugly".  Surprise, surprise!  Not only did the AM receive get stronger, but the hum vanished (Huh?). I would have never guessed that a bad R.F. receiver front end tube could introduce A.C. hum on the receive audio, but somehow it did, even with the volume all the way down.  I gave it a quick alignment and discovered that one of the cans had a cracked slug in it, so I swapped the can with one from "Ugly".  So when I finished the alignment, the receiver is responsive down to .2uV, which is real close to what I would expect, and the audio is clean.  Another surprise came when I tried the manual tuner again, and found that it was now not only working, but the dial calibration was very close.  Sensing the potential for a hat trick, a Trifecta, or a tick-tack-toe, three in a row, I optimistically switched to SSB hoping to see it now working as well.  But alas, the SSB receive is still down for the count. The S meter also has some problems. I was able to zero the meter (Which seems to drift a whole lot more than I'd like to see), but I did not have enough adjustment range to set S9 with 50 uV of input signal. The meter needle will slam against the glass when I key another radio, so the meter has enough sensitivity. I am wondering if there is an AGC problem. But that will have to wait until the SSB receive is fixed (And who knows, the problem might be related). At this point, I could probably throw the rig on the antenna and debut it for the locals. But I think I'll wait until it's completely fixed first.

 

Updated remaining issues:

SSB receiver dead.

Align synthesizer and SSB TX.

Align and neutralize the TX final and driver tube.

Resolve the "S" meter issues.

 

Parts cannibalized so far from "Ugly":

2 tubes

Resistor from the Aux Audio board.

Relay.

Balanced modulator board (But may be able to swap back)

455 Khz I.F. can.

Mic Gain knob.

 

Over the weekend, even more progress was made.  I went to work on the SSB I.F. section by tracing signal backwards from the 1st stage.  I soon found that a screen grid bias resistor on the 2nd SSB I.F. amp was open, which prevented the stage from working.  It was odd for me to see a resistor (especially a 2 watt carbon resistor) actually open completely up without visible signs of burning.  I think I've only seen this 2 other times in 30 years.  Normally when a resistor opens, it had very visual signs of excessive current flow (I.E. it's burned).  Replacing that resistor corrected the problem, and also loaded the +270 volt line back down to about 280V instead the 315V it had been running at.  At this point I started to hear signals on SSB, but they were very low in volume.  Further checking revealed that there were (2) 2N3904 transistors in the SSB AGC stage which were both bad. I had to wonder what killed them, and my best guess was that the +14V supply had jumped up due to the fractured solder connections I had discovered and corrected when I first inspected the regulator board.  With the full unregulated 25V applied, the transistors died a painful death.  Once the 2 transistors were replaced, and with one more alignment, SSB receive was finally working properly.  Now that the receiver was complete (except for the "S" meter calibration), I set my sights on the transmitter.  I performed the neutralization procedure and this time was successful. I also aligned the carrier oscillators and the carrier balance. I was not able to completely suppress the carrier, so I swapped the Balanced Modulator board back with the original board, and this time the alignment went fine. I then turned to the frequency alignment of the main synthesizer. I went through all the channels and attempted to set all the frequencies dead nuts on. After it was all said and done, I was left with 2 AM and 2 USB crystals which could not be adjusted on frequency.  3 of the 4 crystals had drifted low and one was high. Rather than trying to swap with the crystals from "Ugly", I decided to just change the fixed capacitors in parallel with the trimmer to give me additional adjustment range. AM transmit audio still looks a little strange on the scope, and I'll visit that again as I begin the final little clean-up checks to finally finish this radio off.  I also swapped the two main tuner knobs from "Ugly" since they were in better shape. I also want to revisit the receiver's performance. While the sensitivity seems "ok", it is not outstanding, which is something I would expect from such a premium radio. I still suspect that there is either a tube which is a little low on gain, or that there may be other parts which have drifted out of tolerance.  Considering all the current this radio's circuits draw, and all the heat it generates, caps drying out and resistors changing value is not out of the question.  Add in the fact that the radio's over 30 years old, and it becomes very likely.  It'll be a painstaking process though, since the sensitivity is already fairly good.  Consequently, without a "perfect specimen" to compare to, it'll be hard to know which stages are performing within spec, and which are slacking a little.  I'll probably swap tubes around, measure voltages and resistor values, and shotgun replace electrolytic or paper caps.  In the process, I also hope to correct the ills of the "S" meter.

 

The next day I took a stab at trying to figure out why the "S" meter could not be set properly.  Not being able to see anything obvious (Like a drifted resistor value) wrong in the circuit, I dropped the fixed 1M Ohm resistor in series with the S-meter adjustment pot to a 100K Ohm value.  Once that was done, I could easily set the meter to the proper reading with a 50uV input. But I can't help but wonder if I had just performed a band-aid fix which covered up a different problem.  Once the S-meter was set, I then checked the linearity of the signal scale, and I was a bit disappointed. It's not as linear as my Hy-Gain 623. It's linear between S-7 to about +10db over S-9.  But outside of that range, it doesn't track properly. It's not nearly as bad as my Realistic TRC-451, and many other newer radio designs, but I just figured that a premium (priced) radio such as the Tram, would have a better "S" meter.  I also swapped the R.F. Gain pot with the one from "Ugly", since it operated far smoother and with fewer dead spots.  I also bought some NOS tubes from E-Bay to replace some of the aging ones in the Tram.  Hopefully that will improve the overall performance.

 

I finally debuted the radio on the air for the locals.  Everyone said that the audio was strong and the receiver seemed to be ok. I still want to play around with this radio a bit more.  I want to try some different tubes, and I'm not all that happy with how much the "S" meter zero drifts, and I may try to modify that a bit.

On-the-air usage has also exposed another problem; the noise blanker appears to be inoperative. Further checking into this revealed that one I.C. and two  transistors were bad.  After replacement, I was able to align and observe the gating action of the N.B. circuit.  But I haven't had any pulse type noise to "blank" to verify if the circuit actually does an effective job.  During the rechecking of the rig, I discovered that the manual tuner was not working correctly.  It would seem that when the manual tuner is selected, both the xtal synth and the manual tuner are active, which creates some interesting frequency mix products in the transmitter.  I suspect that someone tried to perform the transmit VFO mod, but did not do it correctly.  As I suspected, after a thorough investigation, it was a simple case of "mod gone horribly wrong".  I corrected the problems, and now the manual tuner works correctly on transmit and receive.

 

A few weeks later, I changed out all 5 6GH8 tubes with NOS replacements.  This has resulted in a slight improvement in receiver sensitivity, and more importantly has corrected the earlier issues with the "S" meter.  The meter zero is now stable and it now tracks signal fairly linearly, as I would expect.  The new tubes also put a little more kick in the transmit audio, as I now have to back the microphone gain back quite a bit from the earlier setting.

 

For the near term, I will enjoy this radio and hope that it lives up to the expectations that I had for all these years.  As time goes on, I'd like to replace all the electrolytic and wax paper type caps, as I am sure they have all drifted with exposure to heat.  I also want to check the value of some of the resistors which carry a heavy current load, so ensure that they haven't drifted.  Replacement of the rest of the tubes is also a probability.  But all in all, it would appear that I did manage to make one good radio from the combination of a "Bad" and an "Ugly" rig.

 

Total parts replaced:

10 tubes

4 transistors

1 I.C.

3 resistors

7 caps

1 455 Khz I.F. can

1 R.F. Gain pot.

6 knobs

 

Work done:

Undid power mod.

Corrected VFO tuner mod.

Fixed numerous solder connections and P.C. trace breaks.

Tracked down and replaced defective parts.

Aligned whole rig.

 

And here it is, proudly running on my work table. It'll be an even more challenging project just to find a space on my operating table for this huge radio.....

 

 

 

But what ever became of "Ugly"? Don't worry, I haven't forgotten about it.   In fact, that radio faired much better than I initially expected.  I only had to steal a small number of parts, mostly cosmetic, and depending on whether I can obtain a relay and some new tubes, I should be in good shape to begin restoring "Ugly" fairly soon.  Be sure to look for Part 2 to see how that project pans out.

 

 

In my last piece, "I had a Dream", I told the story of my long time desire to own a classic Tram D201, and of my good fortune in finally obtaining, not one, but two of the rigs, both of which needed some (quite a lot of) TLC. The story went on to document the process of bringing back "Bad", the better of the two rigs. Well, now it's time to set my sights on "Ugly", the worst of the two rigs.  My first look at this radio left me with the feeling that it was beyond hope and I would probably just use it as a parts rig.  But after having the experience of the first rig under my belt, and along with some net scavenged information and some very valuable advice from others who have hoed this row before, it has given me a little better perspective and a more optimistic expectation of what's in store for me when I set out to complete this project.

Here's the rig as I first looked at it:

"Ugly" was in a bit rougher physical condition than "Bad" was.  It definitely had obvious signs of long term (mis?) use. This rig obviously did not sit on a shelf for most of its life, that's for sure.  Because these radios generate a lot of heat (Especially if you try to "soup" them up), one of the previous owners elected to cut a hole in the top cover most likely to accommodate a cooling fan, which was long gone by the time I got it.  There was also a fairly large chunk broken off from one of the woodgrained side panels.  But if the exterior condition appeared to be a bit rough, this was nothing compared to what was waiting once the cover was cracked open.  At first glance, it  didn't look too bad, as it contained a fairly complete set of parts, and everything that was there seemed to be in the right places.  But a closer examination underneath showed that some of the circuit boards were blackened from long term exposure to heat.  A handful of circuit traces  were also lifted, and nearby solder connections showed a dull, overheated finish most likely occurring from excessive current draw.  Along the way, the rig was band-aided by "technicians",  who had performed "cut and jump" patches in a valiant attempt to keep the rig alive.  These "repairs" were done rather sloppily and may have actually contributed to the rig's problems.  The relay was robbed to bring "Bad" back to life, and both the audio and R.F. final output tubes looked well used.  All of the tubes were there, but the R.F. front end tube had been swapped with the defective one in "Bad". 

I began my task by trying to repair the lifted circuit traces, and the badly mounted tacked on repair parts. Along the way I accidentally cracked a 1/2 watt resistor in half, which was sloppily mounted on the foil side of the PC board.  This disturbed me at first, but it turned out to be a blessing in disguise. Since I had broken the resistor, I naturally had to find out what part it was.  I identified the resistor as R403, which was listed on the schematic as a 2.2K ohm resistor. What I had in my hand was something like a 39K. Huh? I then instinctively checked R402, which was the other resistor in the chain which fed V400's plate and screen grid. As I suspected, R402's value had been changed as well. The schematic called for a 47K but instead it was about a 4.7K Ohms. These changes would result in roughly the same grid voltage, but a much lower plate voltage.  I checked the other (now working) rig to see what values were in that, and they matched the schematic.  So I replaced both resistors with the proper values.  I wondered why these parts were changed in the way that they were.  Was this a method to lessen current draw, a performance or reliability enhancement, or simply the product of a knucklehead who can't read the resistor color code?  I installed the proper parts from the component side of the board and repaired their associated PC traces with some buss wire and super glue.  After a night of intensive surgery, the bottom of the boards look much better.  

Here was the before view of one such section:

Here's the same area after I cleaned it up a bit:

It still isn't all that pretty, but it least it's a more solid connection, and there aren't those little jumpers dangling in the breeze.  So with that out of the way, I moved on to other issues.

When Art had first tried to fire up the radio, he noticed that when he turned it on, the lights in his room dimmed, which is a sure sign of an unusually massive current draw.  He wisely turned it right off.  Well, I was able to determine that there was a dead short on the 425V supply, which would account for the huge current draw.  A check of the primary fuse showed that someone had replaced it with a 20 amp fuse (it calls for a 3 amp). Ok, time to climb on the soap box for a second......  What do people think a fuse is for anyway? One day the rig blows the normal fuse, and when you replace it, it blows again, so the answer is to replace it with a big honkin' fuse? Well gee, now the fuse doesn't blow any more, but what is all this smoke pouring out of the rig? HELLO!!!!!!!!!!!  Sorry, but I have little tolerance for idiots.  Well, a little circuit tracing revealed that the source of the short was one of the sections of the multi-section 40 uF C5 filter capacitor.  None of the other sections were shorted, nor were the sections of the other multi-section cap C624.  But C624 had a slightly bulged  bottom, which is an indication of outgassing or other immanent failure.  So it looks like both caps will probably need to be replaced.  I hope I can find NOS multi-ganged caps. As an alternative, I can probably use some of the caps I'd scavenged from computer switching power supplies.  These are smaller and usually of a higher value, and I can probably fit them in place without too much difficulty.  I also noticed that the two 47 Ohm resistors between the HV rectifiers and the shorted cap were burned (think: 20 amp A.C. line fuse).  One was so bad that it was cracked in half. Those were replaced in short order.  The remaining issue was to replace the audio tube bias resistors on the BA plug-in board.  I chose to use (It was the closest value that I had on hand) an 820 Ohm 7 watt to replace two burned up 2 watt resistors. Yea, it's a little higher in value than the two originals, but it shouldn't affect it all that much.  If anything, the tube will draw even less current.  If I see problems with the audio stage, I can always run out and buy the exact values later. Through the course of checking out the plug-in circuit boards, I noticed a cap (C427) lifted from the circuit board. This seemed odd, but the reason it was lifted became apparent soon enough when I tested the cap and found it to be shorted. Hmmm, I've found two caps shorted so far. I'm not sure I like where this is going. And I still haven't put power to this thing yet. I sure hope that when I do, that I'm not greeted with a shower of sparks, or a mushroom cloud full of smoke.  Finally, I replaced two of the diodes in the balanced modulator which had been previously changed to parts which did not match the original value. I would think if you were trying to create something that was balanced, that the parts should all be of the same type. This might have been the reason why I could not get sufficient carrier suppression from this board when it was installed in the other Tram. I also replaced the balance trimmer cap (C207), as it had become brittle and snapped during the tuning process.

I finally put power to the rig 3 days after starting on this project. Being somewhat skittish with the burned parts and shorted caps,  I chose to ramp the voltage up slowly with a Variac. I also replaced the A.C. line fuse with the proper 3 amp value.  I temporarily stole the relay back from the working Tram to use to test this one. I plugged it in and started turning up the Variac. I tested voltages as I brought up the power and they all looked good, at least the HV short is gone. However, AM receive does not appear to be working, as I could not hear the signal generator.  SSB receive does seem to be working, at least the I.F. does, as I can hear a rushing noise. The audio appears to have some static popping noises as well.  I ran out of time before I could try the transmitter, so I'll take that up on the next go around.

On Day 5, I picked up where I left off, by powering up the beast.  As the rig warmed up and voltage was slowly increased, I started hearing static popping from the speaker.  Thinking about the bad caps, I started probing the HV supplies with my scope, to see if the voltages were spiking due to filter cap breakdown.  Sure enough, I noticed fluctuations on the 410V supply.  I then cut the remaining sections of filter C5 out of the circuit and subbed in another cap. This time the popping noises stopped, but there was still a hissing noise which was constant no matter where the volume was set.  Subbing out the audio driver tube (6GH8) cured that problem.  I was now able to see a clean SSB receive.  In fact the SSB receive was not only working, it was working well, as I was able to drop well below 1 uV and still hear the signal.  The manual tuner also seems to be working.  AM receive, however, is still totally dead. But this should be fairly easy to track down.  My first area to check will be the 2nd local oscillator (V301) and then the 455 Khz I.F. chain.  In the meantime, I decided to try the transmitter, but for some reason the relay would not kick over. I could hear it trying, but it was acting like there was not enough voltage across the relay to fully pull it in.  I then pulled the BA board, and I noticed that the three relay voltage dropping 10K Ohm resistors (R's 611, 612, 613) were all hot to the touch.  Well, if the relay was not energized, there should not be that much current flowing through the resistors.  Suspiciously, there was another of those .22 uF 450V caps (C639) from the load side of those resistors to ground.  A quick check with the ohm meter showed that, sure enough, that cap was shorted. That makes 3 shorted caps found so far. This isn't looking so good......  At some point, all electrolytic and other non-disk type capacitors should probably be changed out.  Once C639 was pulled out, the relay could be keyed and the transmitter could be tried.  Both AM and SSB transmit appeared to be working well, with strong audio.  On my next opportunity, the AM receiver will be gone over and I should be able to get it working.

Parts tally so far:

  • 4 burned resistors.

  • 3 shorted caps.

  • 2 changed diodes.

  • 2 wrong resistors.

  • 2 bad tubes.

  • 1 bad trimmer cap.

.....and a partridge in a pear tree.

 

The next day, I dove into the AM receiver by tracing signals.  I was getting a signal at V401, but by V400, it was gone.  Checking the voltages on the tube showed the same 250V  on the plate and the screen grid.  Replacing the tube cured that problem, and with it, the AM receiver started coming to life.  I performed an alignment and brought the sensitivity to where it should be.  But there was still a problem. The "S" meter would not deflect to more than S3 for 50 uV of signal. This was a similar problem to what I found in the other Tram only worse.  The last time, I cheated and changed a resistor value to allow me to adjust the meter. This time, the signal voltage was just too weak and I had to find out what the root cause was. There were other problems too. There were still occasional pops in the speaker.  I had thought that I fixed this problem when I replaced the HV filter caps, but the problem resurfaced again.  These pops seemed to increase in intensity when the rig was on for a while or when under an increased load (like when the transmitter is operated). There isn't much in the HV power supply circuit either. There's the parallel pair of 47 Ohm resistors (R3 & R4). There's a 100 Ohm series resistor (R6) along with the rectifier bridge.  First, I replaced R3 & R4 , with no apparent change. Then, as an experiment, I jumped out R6 and dropped the voltage on the VARIAC so that the HV equaled the proper 410V. This seemed to help, but there still seems to be an occasional pop.  I'm thinking that the rectifier diodes may be breaking down as the load increases. They were, after all, subjected to the shock of a dead short, and having to sink a ton of current that they would not have otherwise.  By lowering the VARIAC, I might have lessened the load enough to keep the diodes at bay.  I will have to wait until I can get some HV diodes to check that theory.

 

In the meantime, I started looking at the transmitter.  I aligned the oscillators, the balanced modulator, and the final neutralization and output and all looked good except for the modulation envelope.  It seemed to lack enough audio drive.  I thought about the 820 Ohm resistor I had placed on the BA board to replace the burned 220 Ohm originals.  So just for a test, I swapped out the BA board from the other (working) Tram.  This time the modulation looked good.  So I went back and tacked another 1.3K 5 watt resistor across the 820 Ohm on the BA board for that radio, and that did the trick.  The modulation looked good again.  I'm sure there is an optimal value to use to set the proper bias and for optimal D.C. gain, and once I get everything working, I will dial that value in.

 

The next night, I started aligning the crystal synthesizer and, like the other D201, there were 3 crystals which could not be netted on frequency.  I decided to make a note to revisit this area later, as I want to cure the rig of all of it's major ills first before I fine tune the crystal frequency.  So I returned to the AGC/S-meter issue.  Both SSB and AM readings appear to be equally low, and that should be a clue.  After spending what seemed like an inordinate amount of time looking for parts out of tolerance and swapping out tubes, I gave up and changed the value of R428 to a 100K, like on the other Tram, and adjusted the meter. It bothers me to have to cheat like that, but with the receiver working properly, and no obvious problems waving their hands in the breeze, I did what I needed to do so that I could move on.  The next item on the list was the manual tuner modification.  This Tram, like the other, had the popular manual tuner mod performed which allows it to function on transmit like a VFO.  Also, like on the other Tram, the mod was performed incorrectly, allowing the crystal oscillator to run along with the manual tuner resulting in some strange spurious transmit products.  So now I'm cleaning up that area.

 

So as it stands now, the "Ugly" Tram is pretty much functional. I do have some remaining issues though before I can give it my seal of approval:

 

  • Clean up the HV power supply by installing lower value filter caps or a higher value dropping resistor to get the HV to run at the proper level without having to use the VARIAC to lower the line voltage.

  • Trace down the "Popping" noises coming from the HV power supply. May need new rectifier diodes.

  • Replace some formerly shorted bypass caps with new replacements.

  • Align synthesizer crystals.

The next few days were spent taking care of these issues.  The "popping" noise seems to have been caused by poor contact in the Molex connector on the "BA" board.  Cleaning and tightening the connector fingers seems to have finally solved that problem.  I also picked up some caps and high power resistors from Art, and have replaced the shorted caps.  I replaced the R3-R4 combination with a single 100 Ohm 10 watt resistor, in order to drop the HV down to the proper levels with the filter caps that I am using.  The values of the new caps are much higher than the originals, and should provide better filtering.  But they had also caused the voltage to rise above their nominal value.  The new resistor corrects that.  I also went through the synthesizer and did my best to align the crystals. Some of the crystals were located in a place where the selector switch blocked easy access to the solder side of the board, so I was not able to completely net in all the frequencies perfectly.  But they are all close enough. The manual tuner was also cleaned up so that it functioned completely independently from the crystal oscillator.

 

At this point, it would appear that I have a completely functional radio.   A pretty good feat considering the less than optimal condition of the radio when I first started this project, and of my dubious prognosis and how close this radio came to simply becoming a parts donor.  Of course, I am still borrowing the relay from the other D201, so at some point another relay will need to be found so that this radio can have a fully useful life once again.  I'm sure Ebay will come to the rescue there.  While I had to "re-engineer" a little more on this radio compared to the other D201, and this radio got the "hand-me-down" parts, it's working surprisingly well. I plan on returning this radio to Art at some point, so that he can enjoy it.


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