[Elecraft] K2 Headphone Output

[k6se@juno.com]

Thanks to all who replied to my query about increasing the K2's
headphoine output level.

Two individuals reduced the values of R35 & R36 to get more headphone
output.  One of them said there was a mod for this on the Elecraft Web
site, but I couldn't find it.

One individual correctly stated that if R35 & R36 were reduced to zero
ohms, a mono phone plug inserted into the front panel headphone jack
would ground out the audio (which explains the reason for those
resistors).

Two individuals incorrectly suggested that there might be an error in the
speaker wiring.  This is incorrect because the speaker wiring is
automatically disconnected whenever headphones are plugged into the front
panel headphone jack, therefore speaker wiring has nothing to do with the
problem.

One individual said that the headphone output varies widely from K2 to
K2, even though they all use the LM380N-8 audio amp IC and the same other
components in that circuit

Most others said to use 32-ohm headphones, which I already do (I also
tried my 8-ohm headphones which yield slightly less volume with the K2).

Even though I haven't experienced a "noisy" AF gain pot, the benefits of
Wayne's suggested mod to the AF gain pot circuit seem worthwhile, so I'll
do that mod.  Max volume is not affected by this mod.

On the bottom of the RF board, I temporarily bridged AF OUT to the tip
connection at the front panel headphone jack.  This made a BIG, BIG
difference in the amount of audio to that ear.  I therefore will reduce
the values of R35 & R36 to around 22 ohms or so.

73, tnx for the info, de Earl, K6SE