[spierce328]

Hello all. I can use some help on another mystery problem, this time on a Philco 38-9

http://www.nostalgiaair.org/Resources/262/M0013262.htm

This is a customer radio that will drop the volume after about 10 min playing. Low to moderately strong stations drop out completely, while stronger stations are still at a listenable level, although equally diminished.

Measuring the AVC voltage tuned to a moderately strong station, at the junction of resistor 15 and cap 3, I see that the voltage starts at about -5 VDC then slowly rises to about -.5 VDC, where the radio abruptly loses volume. Turn is off and let if cool, for a few minutes and and cycle repeats.

I have replace all Electrolytics (twice), all other caps (including the two micas ) and most resistors including 43
I have swapped tubes multiple times
The power transformer voltages are stable
The voltages on all tubes are within tolerances

I have spent hours and hours on this one. I would appreciate any suggestions where I might look as to the source of the disappearing AVC voltage.

Thanks Steve