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is it possible to increase ssb output on the Tram D201

klj2497

Active Member
Jan 19, 2017
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I know the tram D201 is not the best ssb radio, but i like the radio and im hard headed so I jumped the small power resistor.to see if that helped ssb it increased am but the ssb was the same about 10watts swing lsb. I would like to get about a 15-20watt swing.
 

Low SSB output is usually an issue with the ALC being turned up too much or something on the balanced modulator board. If AM has good power, the alignment of T-200, 201 and 203 are probably close. If they are probably aligned, the problem is often 3 electrolytic caps. They are C-235, 236 and 237. As they dry out, the SSB mic pre-amp begins to lose gain. Some D201 radios just need a little extra mic gain on SSB and if that's not available, consider replacing R-251 with a 33 ohm on the balanced modulator board.
 
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Replacing all five electrolytic capacitors on the Balanced-Modulator board will probably help. Takes three 1uf 50-Volt, one 33uf 25 Volt and one 100uf 25 Volt.

More than once I have used a 47uf for the 33 when I ran out of that value. Doesn't seem to affect the audio.

73
 
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Yo: I had almost zero SSB output on a used Tram 201A that had a bad 180 pF Mica Cap C242 that is across the output of the balanced modulator T200. A new Cap and replacing all the other caps as nomadradio is a good call. Good luck.

Jay in the Great Mojave Desert
 
Thanks guys, It looks like The five capacitors are newer ones. one of them the c211 is a 100uf 100v, instead of a 100uf 25v . Im going to check them to make sure they are okay. Im ordering some 33 ohm 1/4w resistors for r251 and maybe a 180pf/sm. cap. for c242. im going to check it. I am also ordering capacitors for a varmint xl-600 i hope to have that running right again soon.
 
Using a 100-Volt part where the factory used 25 Volt won't cause any trouble if it fits. The higher the voltage rating, the larger a cap gets.

The three 1uf 50-Volt electrolytics are most likely to affect SSB audio. But if they're fairly new, they're probably okay.

73
 
The Tram D201 diagram shows the RF Voltages that your supposed to have at each stage, which is a big help. I dig around and found my old HP VTVM that uses a tube as a RF Pick Up that the lowest scale is 15 Mv (.015 Volts or 15 Mv ) which is a big help. In tracing which stage ain't ah hummin and buzzin.

Jay in the Great Mojave desert
 
Yeah, the diagram has alot of good stuff. Thats sounds like a nice meter., I have one of those rca voltohmyst wv-77e that i like to use.
 
OK: Please let us know what all you find wrong with the low SSB output problem.

Jay in the Great (hot, windy, dirty) Mojave Desert
 
The lsb output swings about 8watts, on usb its about 13watts. am keys up at 3 1/2 and swings to about 5watts. after i whistle into the mic a few times, the am dead key sometimes rises to about 4.2watts i am really baffled.
 
i measured pin 10 and 11 on the balance mod. board there is a difference, in usb pin11 had .25v, and in lsb pin10 is .48v. I checked my other tram and the two numbers are about .46v.
 
Do you have a frequency counter with a pickup probe? Checking the frequency of the two carrier crystals would be my next move.

USB should show 6.2535 MHz, LSB is 6.2565 MHz, same for AM.

Best place to probe for this is the emitter of Q205 on the balanced modulator board.

If the AM/LSB crystal is way off frequency, this would explain the problem.

A 'scope at the emitter of Q205 would reveal if that crystal is just weak, delivering half the drive level you get from the USB crystal.

Less common, but possible.

Any difference between USB and LSB performance is nearly guaranteed to reside on the balanced modulator board.

73
 
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Thank you, Nomadradio. Yes, i have a frequency counter and probe that helps to narrow the search area. I have purchased an oscilloscope it should be here maybe tomorrow. and i have been reading the manual ive downloaded its a tecktronix tas465.
 
The upper and lower ssb is on frequency, how do i set up the radio,to measure the lsb/usb drive levels from the Q205 emitter
 

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