Tram 201a channel selector problem

[Jimbo165]

I just picked up a 201a is there anyway the channel selector can be fixed or possibly taken partly apart to spray some contact cleaner inside. Mine is acting up on channels 31 to 35. As many 201a out there seems like someone could come up with a fix???. Thanks

 

[nomadradio]

There are some posts on YouTube that claim you can "rehab" the black selector made by A-MP. I never had any luck making the original black selector last more than a couple of days this way.

The factory came up with a better-built selector made by a company called "Standard Grigsby". It's gray, larger then the original selector, and the pins do NOT line up with the holes in the circuit board.

Well, some of the holes physically line up, but you still have to drill a few new ones. The real kicker is that NOT ONE of the pins is in the correct position to agree with the old black selector. You have to pull up all eighteen (I think) foil traces to the holes for the old selector. A thin bare wire is looped around each pin of the new selector and lap-soldered to the correct foil trace to get it installed. Because of how crowded these wires will be, you can't just use thermoplastic tubing. Clear teflon sleeve is the only insulation that will survive the heat from soldering wires this close to each other.

Thought I had a pic of this kluge, but can't find it right now.

But that's the good news. Bad news is that the gray selector is now unobtanium. Barkett ran out of them some time ago, and he had the last remaining supply of them that I know of.

But hey, there's a bonus. We have found that once you replace this selector and get it wired right, you will usually find at least one crystal that's too far off frequency to set with the trimmer cap. Sometimes several of them.

At least you won't know which ones and how many until the new selector has been laboriously installed.

I'm still working to raise the money to replace that crystal board altogether with a modern synthesizer and display.

No promises about when or if that may actually happen.

73

 

[Jimbo165]

Thank you nomadradio I did get on utube and see the selector apart. On my 201a the channels 31-35 were the ones I would have to tap selector for them to work. It may not have been a good idea but I took off selector back and sprayed some WD40 in there to help clean and lube inside. Now it is working just like it should when on crystal select but when on manual and selector on 31-35 the vfo will not work. Turn channel selector to 36 up or 30 below vfo works fine. It can be used at least now. I want to do the VFO transmit mod.

 

[TM86]

There are some posts on YouTube that claim you can "rehab" the black selector made by A-MP. I never had any luck making the original black selector last more than a couple of days this way.

The factory came up with a better-built selector made by a company called "Standard Grigsby". It's gray, larger then the original selector, and the pins do NOT line up with the holes in the circuit board.

Well, some of the holes physically line up, but you still have to drill a few new ones. The real kicker is that NOT ONE of the pins is in the correct position to agree with the old black selector. You have to pull up all eighteen (I think) foil traces to the holes for the old selector. A thin bare wire is looped around each pin of the new selector and lap-soldered to the correct foil trace to get it installed. Because of how crowded these wires will be, you can't just use thermoplastic tubing. Clear teflon sleeve is the only insulation that will survive the heat from soldering wires this close to each other.

Thought I had a pic of this kluge, but can't find it right now.

But that's the good news. Bad news is that the gray selector is now unobtanium. Barkett ran out of them some time ago, and he had the last remaining supply of them that I know of.

But hey, there's a bonus. We have found that once you replace this selector and get it wired right, you will usually find at least one crystal that's too far off frequency to set with the trimmer cap. Sometimes several of them.

At least you won't know which ones and how many until the new selector has been laboriously installed.

I'm still working to raise the money to replace that crystal board altogether with a modern synthesizer and display.

No promises about when or if that may actually happen.

73

Speaking of kluges, could something be rigged up with a rotary encoder, microcontroller, and some digitally controlled switches to emulate the channel selector? Wouldn't fix the crystal aging problem but might give a few more years of use to an otherwise good radio.

Or would the voltages involved blow TTL or CMOS circuits necessitating the use of expensive relays?

I have to ask as I don't have a D201 to play with, and they're a bit spendy to satisfy my mostly idle curiosity.

 

[Jay Mojave]

Hello All: I picked up a Tram 201A 40 channel rig a few years ago in almost good shape. Missing a mode and no SSB made it not fun to use. After several weeks of trouble shooting I found a broken wire, shorted capacitor on the Balanced Modulator Board, two weak tubes, and quit a few bad resistors and suspect capacitors.

Adding a quiet fan in the back to help cool it off and a quick alignment I noticed it was still about 10 to 20 dB down in the receive but the pre amp in the DX-300 amp helped some what. After weeks of all this intense work it was ah hummin and buzzin again and it was a real enjoyment to use. Ah yes the channel selector switch was now intermittent on most channels, and would cut out just when I was in a QSO, how wonderful!

I noticed that when the channel selector knob was slightly held in the up position I had a solid transmit and receive. I installed a 5/16 vacuum hose between the lower lip of the chassis and channel select knob, allowing a slight pressure being pit on the channel select knob, allowing the radio to work as expected.

I also would like to see a DDS VFO for the Tram and other radios. Maybe when I get some time I could buy one and make it work, but would love to see what Nomadradio comes up with if he sells a unit.

Looking over a few DDS VFO sights:
http://www.pongrance.com/
http://faculty.frostburg.edu/phys/latta/ee/vfo/vfo.html

Jay in the Great Mojave Desert