[Elecraft] Fine tuning AF1

[Ron D'Eau Claire]

I realized later that I didn't include the audio lead between the K2 and AF1
in bypassing suggestions. Any bit of wire connected to the AF1 can,
potentially, bring in RF, and your description of the interference
(distorted sound, buzzing, clicks, etc.) are all strongly suggestive of
enough RF voltage to cause various junctions in the audio ICs to conduct and
mess up bias levels, etc. 

Ron AC7AC

-----Original Message-----
Mike, your description does not say how close that "miracle whip" is to the
KX1. Often they are mounted right on the radio. That puts the RF field as
close as possible to the KX1 and AF1. 

...you can try
putting bypass capacitors on the power and phones leads at the AF1. It's
likely the RF is being picked up by one of those leads rather than being
picked up by the AF1 circuits directly. Put a small value capacitor - 0.01
through 0.001 uf - across the power leads and audio leads on  the pc board
near the jacks. The larger value cap will be more effective at the lower
frequencies. That may reduce the RF getting into the circuit itself enough
to eliminate the issue. 

Ron AC7AC