[Elecraft] K3 headphones

[Paul Christensen]

>> I has tried replacing the 10uF caps with 100uF in AF-amp, also in
>> data-sheet for LM4811MM we see grounded pin 10 have to add for 1uF cap.
>> The result is excellent with my ProSet.

If anyone is going through the trouble of changing the 10uF caps at C9 and 
C13 on the front panel DSP Board, I suggest going to 330 uF to ensure that a 
broad range of headphones are covered, including old models with fairly Lo-Z 
drivers.

http://www.n1eu.com/K3/k3audiomod.htm

The National LM4811MM spec sheet notes that the bypass cap (Cb) value as 
described above is critical with respect to turn-on clicks and pops.

>From the data sheet:
"Capacitor Cb is the most critical component to minimize turn on pops since 
it determines how fast the LM4811 turns on."

It's already at 10 uF.  Before changing it, I would test for clicks/pops 
both ways to ensure that artifacts are not present.

Paul, W9AC