Plate voltage and current are normal and current shows a minor decrease when going to transmit. Grid current does not move.
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I would unplug it, discharge the HV and power the relay circuit from an external 12-Volt DC supply. A small supply with a current limit around 1 Amp is a sort of swiss-army knife tool for this kind of troubleshooting. Gator clip it to the standby switch to power the relay alone. Keying it with only the 12-Volt circuits live is just safer. Permits you to shut down the dangerous voltages and still follow the signal to see where it gets lost.
And that's what it sounds like, the input signal isn't reaching the tubes. The green wire on the rear circuit board has been cut, hasn't it? That wire disables the 10-meter band until it's cut.
If you don't have a 'scope to follow the radio's drive signal through the input circuits, next best thing is a DC continuity test from the center pin of the radio socket to the blocking capacitor on the tube cathodes. This would reveal a relay failure on the input side or a connection that's come loose. Just discovered I don't have Ameritron manuals on file at home. Gotta copy them from work to bring home to be more specific than that.
73
And that's what it sounds like, the input signal isn't reaching the tubes. The green wire on the rear circuit board has been cut, hasn't it? That wire disables the 10-meter band until it's cut.
If you don't have a 'scope to follow the radio's drive signal through the input circuits, next best thing is a DC continuity test from the center pin of the radio socket to the blocking capacitor on the tube cathodes. This would reveal a relay failure on the input side or a connection that's come loose. Just discovered I don't have Ameritron manuals on file at home. Gotta copy them from work to bring home to be more specific than that.
73
This is the open frame relay. I have powered the relay and check continuity from the input coax connector. With the relay powered, transmit, there is open between the coax input and output. Relay not powered, the input and output have continuity. Not O-scope here..