[Collins] 75S-3 problem

[Dr. Gerald N. Johnson, electrical engineer]

BFO crystal or switch. Does it sound the same as tuning in LSB on AM or
is it like tuning in LSB with the switch in the USB mode? Check for
bandpass with respect to tuning by turning on the calibrator and tuning
past it. If it gets a tone on LSB the crystal is oscillating but off
frequency, if there's no tunable tone, the crystal isn't oscillating.
Either case generally requires replacing the crystal which isn't cheap.

Be sure its not using the tunable BFO, if that's an option with that
model. Or alternatively use the tunable BFO to receive LSB.

73, Jerry, K0CQ, Technical advisor to the CRA.
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.