{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

Sponsored by the Collins Collectors Association http://www.collinsradio.org
Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
Sun AM Net: 29.050 Mc-1200 Central

This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.