Out of the blue this new problem popped up just after I solved the previous noise problem which was due to 1) an intermittent contact between C-12 and a neighboring connection on L-4 and 2) a bad connection on V-4, hidden 53 yrs, that had been good until just now. The mica caps in the tuning circuit around L-4 in attached schematic were sensitive to anything coming close, conductive or not. This had never before been a problem but lately it could be one day then go away the next day. The mica caps C-9, 11, 12, 13, 14 were not sensitive to heat or cold. L-4 was the only component sensitive to cold. Now it changes with temperature and any time I key the mic. The tuning slug is not moving by itself. Once warmed up it will be stable all day, unless I key the mic. I tried swapping out C-11 and C-12 but there was no change so mica caps were reinstalled. In the previous 53 years there has never been any freq drift, now just a brief transmit can cause a shift in freq up or down of over 23 channels which means every channel on the dial can be shifted way off the dial.
I haven't found any loose connections and I've taken multiple voltage readings in Rx and Tx mode but there don't seem to be any significant variations. The only things that seem capable of causing this are caps and maybe a tube going bad. Rx does seem weak. Last week I heard many people, today nothing, but it does receive signals from other transmitters I have. I guess their signals are strong enough. Anybody have a clue?
I haven't found any loose connections and I've taken multiple voltage readings in Rx and Tx mode but there don't seem to be any significant variations. The only things that seem capable of causing this are caps and maybe a tube going bad. Rx does seem weak. Last week I heard many people, today nothing, but it does receive signals from other transmitters I have. I guess their signals are strong enough. Anybody have a clue?
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