[Elecraft] KX1 quirk: no AF nor HF output at all

[pa3gyu]

Couldn't find anything in the archives, so here goes.

My KX1 showed a strange problem. I had put it away in full working order 
about a week ago. Yesterday I wanted to listen to some live CW to polish up 
my skills. It switched on ok, but there was absolutely no audio output. Not 
even a hint of hiss. I tried several headsets, nothing.
Also, there was no HF output at all into a dummy load. I thought it wise to 
refrain from taking it apart at that time...

So this evening I tried again. No HF, no AF, the display was working okay, 
I could switch between all bands and the tuning seemed to be working as 
well. Battery power is 8V. I decided to see if the receiving circuits were 
still with me, but found that the S-meter indicated a strong signal all the 
time: it could not distinguish between the XG1 being switched on or off or 
even being disconnected!

Hmmm... I took out the KXAT1 and without even putting the jumper in the 
audio hiss was there when I turned the KX1 on. I put the KXAT1 back in and 
it came fully alive with all bells and whistless working like a charm.

What the hack is going on here? Anybody seen this before?

Bart de PA3GYU