Today's Mystery Guest (RCA CTC-4)

[Phil Nelson]

I reconnected C202 and disconnected R242. With no signal at the receiver, the waveform at L42 looks like the following and I hear buzzing instead of a clear tone from my SW radio tuned to 3586 KHz:



When I turn on the color bar generator, the waveform changes to this, and I see the same old green bars on the screen (no barberpoling). Louder buzzing from the SW radio:

Originally Posted by DaveWM

I would be tempted to scope and look for clean burst to be coming from the keyer. It like the osc free runs, but adding the control kills it, so maybe the control is not really a nice clean burst, but some video getting in there.

If you scroll back to post #142, you can see three scope waveforms from the burst keyer. The first two looked good, the third (cathode) not so much. I can repeat those now, if that's interesting.

Edit: Well, I'll be hornswoggled. I reconnected both C202 and R242 in preparation for scoping the burst keyer. (Everything is now reconnected, in other words.) To my surprise, I saw rolling color bars, which I can make to hover in place by adjusting the reactance coil (L127).



??

Phil Nelson