Thanks for your comments. I finally tracked the problem to a bad diode on the
AF board. The diode D6 was shorted, providing a path to ground for transitor
Q1 on the rectifier board, through the base emitter junction of the side tone
oscillator
on the AF board..
Additional symptoms were base voltage of Q1 measured at 11.5 volts while key
was up which indicated that Q1 was conducting when it shouldn't. Also, xcvr
would output carrier with mode switch in CW position when VOX control set to
the MOX position. It shouldn't have.
de WB4FPL, Bob
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