[Elecraft] K2 Headphone Output

[Ron D'Eau Claire]

You can easily check the effect of the resistors and caps by plugging your
phones into the auxiliary speaker jack on the back instead of into the
phones jack on the front.

Of course, the FIRST thing to check is to be sure you wired the speaker line
correctly. if you get the wires to the plug that mates with P5 backwards, it
will short out your audio.

In the 2+ years that I have been following this reflector since I built my
K2, the issue of audio volume has come up many times. Some ops had way too
much gain! I was one of those. We kept the AF Gain control down almost at
the minimum stop at all times, and we experienced problems with the pot
being "noisy". It wasn't a problem with the pot, as it turned out, but how
the circuit was designed. The circuit was fine for many K2's but way to
"hot" for others. A mod to rewire the AF Gain pot circuit was added to the
Builder's Resources a while back that fixed that problem for those of us
with too much gain.

At the same time, reports like yours crop up from time to time - too little
gain. I don't recall any "fixes" for that,  but then I wasn't watching
closely since I had the opposite problem.

It appears that there is a very large variation in the amount of audio
system gain from K2 to K2 for some reason.

Ron AC7AC
K2 # 1289



> I find myself using the K2 volume control at max when listening to weak
> CW signals.  Has anyone played around trying to increase the headphone
> output on the K2?
>
> It looks like resistors R35 & R36 and electrolytic capacitors C105 & C106
> (on RF board schematic sheet 1) are there probably to reduce high-pitch
> hiss, but they also do a good job of reducing the overall headset volume.
>  Removing the caps (or reducing their value) and/or shorting the
> resistors looks like it would significantly increase the headset volume.
>
> Any thoughts?
>
> 73, de Earl, K6SE