{Collins} 75S-3 Receiver Audio Hum



    I am experiencing an audio hum in my 75S-3 receiver that seems to be
getting worse let me explain. If I place the receiver in standby and turn
the RF gain all the way counterclockwise and turn the audio gain all the way
fully clockwise I hear a definite hum while in the LSB, USB and CW positions
but not in the AM position. I have changed out V8 (6U8) and this reduced the
hum but  it is still noticeable. If I listen across pin #1 of V8 with a
signal tracer I hear the hum there but not at pins #9 or #8. I have checked
the resistors and tried changing the coupling capacitors
but the hum still persists. Is this a characteristic of this receiver ?

Thank You
Thomas Elmore KA1NVZ
Anchorage, Alaska

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