[Elecraft] K3 with MH2 Mic

[Don Ehrlich]

As many already know the K3 AGC kicks in when the MH2 mic PTT switch is 
pressed and that causes the first few words to be attenuated after keying 
the mic.

Elecraft told me that was caused by the mechanical noise the PTT switch in 
the mic makes and they plan to address it by and by.

Not so!  The stimulation of AGC is caused by a current transient in the PTT 
switch circuit that is coupled into the mic audio line in the mic cable 
going to the K3.
My guess is that a filter capacitor in the K3 is being discharged by the PTT 
switch and that generates a sufficiently high current spike to cause the 
problem.

I just performed surgery on my mic connector to add a 150 ohm resistor in 
series with pin 2 (PTT line) and that is all it took to eliminate that AGC 
transient.  No more lost words.  It was messy surgery and not for the faint 
of heart but it works.

Don K7FJ