[Elecraft] Jumping power on 40 and 80 meter

[Peter]

HI

Last weekend I found out that my K2 didn't work correctly on 40 and 80 meters.
The power on 40 is jumping between 100 and 50 watt when I do keydown
When rotating the power pot, it looks like a bad pot meter. The power is jumps up and down
when I turns it
Its worse on 40 and a bit better on 80 meters. All other bands are fine so its not the pot
meter.

To try to find the error I remove the K2/100 PA. With 15 watt its has still the same
error.

Then I removed the ssb adapter and place  C167 back and 2 jumpers W2/W3. Still the same.

When I look at the drawing there is a RF output detector near the antnne output. As I can
see the label V REFDET goes only to the SSB adaptor (pin 6)

How is the power level set in the K2?
Since 80 and 40 meter doen't share the same band pass filters I think there isn't the
problem
Also the PA is broadband so this one is working good too.
Does any one has a clue to look at?

Peter