[Elecraft] KX1 oscillation

[Phil Wheeler]

I was there last night and all went normally.

I would suspect the audio amp U4.  Make sure all resistance and voltage 
checks there are normal and that all cap and resistor values are correct 
-- and solder joints are good in the area of U4.

73, Phil

Pete Meier wrote:

> Just started Alignment P2 after all previous tests and measurements 
> shown at proper values.
> When I plug in headphones I am hearing a very high pitched constant 
> tone. I assume is something gone into oscillation.
> It is not the sidetone and everything acts correctly. I can
>
> Any idea what might be causing this tone/oscillation? I can hear the 
> sidetone and adjust it but, of course, it sounds distorted mixing with 
> this contant tone. This tone increases volume with the audio level as 
> controlled by the AF GAIN.