Help: HW-101 Carrier Null Problem

[Ted]

Hello to all

I need some technical advice on a problem I am having with a HW-101.

Problem One: I cannot get any measureable RF voltage from carrier null
circuit.  No voltage-- no way to adjust the carrier null.  I have
replaced the null pot twice and all the diodes in the circuit once with
no results.  I have carrier oscillator injection into the balanced
modulator at the correct frequency.  I have replaced tube V16, and Tube
V1.  Don't know what to look at next.

Problem Two:  I get full output with the Tune mode but when I switch to
LSB or USB and key the mic I get full output using an audio generator
for several seconds and then the RF out drops off to zero.  Voltages
check OK in Audio circuit and do all resistances.  I have no way of
checking capacitance--Could I have a  bad capacitor somewhere in the
circuit??

Any help would be greatly appreciate to those of you when a better
understanding  of what is going on.

73
Ted N8GPQ

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