I need some help in getting my TR-4C back on the air. Would appreciate any comments.
The rig was operating normally. I tuned up on 40 meters to about 180 watts out. I noticed that the bias was a little low (about 75 mils). I adjusted the bias on the AC-4 and instead of increasing the plate meter reading, the meter pegged to the left and I lost all output. The adjust bias now has no effect. No smoke. No smell. The rig powers up. Receive works fine. But the plate meter seems to be telling me that bias current is going the wrong way, and the rig won't transmit on any band.
I checked the voltages in the AC-4 and got the following (no load) readings: high voltage=726, low voltage=297, bias= -54 to -94 as the adjustment pot is turned from left to right.
I replaced all tubes with known good ones, including the finals. Cleaned all switches. Relays are closing okay.
I did discover that the negative voltage on TP1 is zero for the 28.5 band, and believe that crystal to be bad (it is about 15 kHz off), but I don't see how this could affect transmit on all bands. I have not checked the 9 mHz crystal yet, but since receive is working okay, I do not suspect it.
Any ideas?
Thanks & 73,
Wayne
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