I have a hand wired Tram d201 it is working fine on receive but as I am transmitting the transmit output drops to zero and no output. Unkey and after a minute will transmit ok again. Any ideas?
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Tram D201 Transmit starting and stopping?
- Thread starter Jimbo165
- Start date
How familiar are you with troubleshooting - specifically, tube PA circuits?
For starters, have a look at all voltages involved with the final. Specifically, screen grid and plate. Be careful. Are any of these dipping as you transmit? And when looked at via scope, are they clean, stable and free of ripple?
Next - possibly gassy tube. Replace with known good part and test again.
Then we'll work backwards to the driver.
For starters, have a look at all voltages involved with the final. Specifically, screen grid and plate. Be careful. Are any of these dipping as you transmit? And when looked at via scope, are they clean, stable and free of ripple?
Next - possibly gassy tube. Replace with known good part and test again.
Then we'll work backwards to the driver.
N8YX, can I slide a dumb question in here please?
I've been in electronics in one way or another since the 70s, but mostly digital. My radio experience is all solid state. I have an understanding of tubes but not A LOT of hands on practice. I also have a good understanding of safety principles and the respect tube circuits require.
I also have a Tram D201A and a Gem GTX-2300 that I will be going through just to bring them back to life.
With all of that said..... when you are scoping around the finals of a tube PA.... does using the probe in x10 mode COUNT... in the voltage input limit consideration on the scope? I hope that question makes sense. I am just wanting to insure that when I key up the tube radio and touch the probe to a point in the circuit..... I don't ignite the probe, it's cable, or ANYTHING ELSE!!!!
I came back to add that the scoope is a Tektronix 425M... the military version of the 465.
I guess I would also add te question that, if a probe suggests a max voltage of (I am just throwing a number in for example here)... say... 300v..... does the x10 switch extend that range at all? Or would MORE than that 300 volts tend to smoke the voltage divider?
I have a VTVM good for something like 1500 volts also.... I am just not certain whether the probes are appropriate for that use,
I would appreciate and thank you in advance for any advice that you might feel like giving!!!! Especially eager to hear safety tips so I can live to learn more!!!!
Bob
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Bob,
A 10x probe should attenuate whatever you apply to it by 10 times. In other words, if you set the scope's vertical deflection to 1V/div with that probe attached it will take 10v to deflect an entire division.
What is the scope's maximum vertical deflection setting? I'm thinking 30v/div...will look the specs up if you want.
A 10x probe should attenuate whatever you apply to it by 10 times. In other words, if you set the scope's vertical deflection to 1V/div with that probe attached it will take 10v to deflect an entire division.
What is the scope's maximum vertical deflection setting? I'm thinking 30v/div...will look the specs up if you want.
If the relay is the original 1975 part, this can easily cause the transmit and/or receive to drop out. There's a reason it's in a socket and not soldered in place.
That radio is fifty years old. The list of things that statistically SHOULD go bad from age alone just gets longer year after year. Quick test of the relay is to flick the short side of it with your finger and listen for noise or dropouts. Do this while receiving and transmitting. A second radio to listen to the Tram's transmit audio will be helfpful. If you see the wattmeter flicker, rise or fall in response to flicking the relay, that will confirm my suspicion. Odds are you'll at least hear some noise. Today's noise is tomorrow's "cut out" symptom.
With any luck the relay for that one will become available again soon.
Maybe.
73
That radio is fifty years old. The list of things that statistically SHOULD go bad from age alone just gets longer year after year. Quick test of the relay is to flick the short side of it with your finger and listen for noise or dropouts. Do this while receiving and transmitting. A second radio to listen to the Tram's transmit audio will be helfpful. If you see the wattmeter flicker, rise or fall in response to flicking the relay, that will confirm my suspicion. Odds are you'll at least hear some noise. Today's noise is tomorrow's "cut out" symptom.
With any luck the relay for that one will become available again soon.
Maybe.
73