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..
Sorry I'm late to this party, not too late hopefully.. You didn't perform the continuity test as instructed.. Your procedure only confirmed the relay is switching properly.. The 2nd part of your test involves checking continuity between the tube cathodes and the RF input from the radio.. Go back and re-read Nomadradio's instructions again.. Just as a reminder: this particular tube's cathode is also the filament.
I did a dc (multimeter continuity check) from the SO239 center pin to the 2 capacitors C8 & 9 (( both have been replace with no change)) before the filament choke L2. from the filament choke to the tube sockets V1, 2, 3.
I did fine the Capacitor C13 from the Parasitic board to the HF coil circuit board to be very low. After replacing that Capacitor Amp would work but Now I have very high SWR back to the radio in Operate but not in standby. $,7:1 and 1.038:1
That is where I'm at now.
This input SWR problem has been discussed many times in this forum.. Does the amp have this high SWR on all bands, or just 1 or 2?? If all bands, I suspect you have issues with other components. If this is a new problem that has cropped up as a result of your repairs, that's where I'd look first.
If it's related to only 1 or 2 (even 3) bands, the problem is in the input matching circuit.. Input coils out of adjustment, input capacitors have drifted in value, input bad switch faulty or burned..