[Elecraft] KPA100 audio problem

[W3FPR - Don Wilhelm]

Neal,

Try plugging an external speaker into the KPA100 external speaker jack - if
my guess is right, you will find the same behavior on that speaker too, and
will confirm my speculation that you have the wires on the AF cable
reversed.

Do check the orientation of the wires from the AF jack to the KPA100 board.
The side of the cable closest to the right side panel (when the jack is
plugged in) should end up at the 'AF' pad on the KPA100 board. Note that the
'copper/silver' conductor usage specified in the KPA100 is opposite that
used in the base K2. It sounds like you have them reversed and you are
shorting out some of the audio when you plug in the ground connections on
either of the 12 VDC of RF connectors.

If the cable wiring is not the problem, I think you should be looking for a
solder bridge from the AF line to something else on the KPA100 board.  You
are correct, there is not much to the speaker wiring on the KPA100 board -
just signal traces and the external speaker jack.

73,
Don W3FPR

> -----Original Message-----
>
> I assembled my kpa100 during the week, what a nice experience!
>
> The functional operation of it is fine, aligned well, tx audio is good,
> temp, etc. all fine.
>
> The problem I am experiencing is with the audio.
>
> If I plug the audio cable only into the k2, audio is as good as the
> original. But if I plug either the 12v line or the rf line, it sounds
> very tinny and distorted. When I  connected the speaker plug from the
> orginal k2 top and then plugged in the 12v and rf line from the kpa100,
> no audio distortion. I assumed I might have wired my speaker backwards,
> but even with both connections free from the kpa100 speaker, it
> distorts whenever I plug in the 12v and/or rf cable. So its something
> on the kpa board itself. The problem is there really is not much in
> terms of audio circuitry on the KPA.
>
> Any ideas?
>
> 73 de Neal
>
>