[Elecraft] K2 Bad CW signal

[Micha DF4WX]

Dear community

I am having problems with my K2. I got complaints about a lousy signal (e.g. rst 591). When I checked my signal with an external RX I heard a kind of a noise instead of a clean CW signal. When I press the "Tune" button, I have a very clear tone (as usual) in the control-RX. With all power levels the PA current is the same both in tune and in normal CW TX-mode. Only the resulting signal is different.

What could be the root cause of this issue? Are the signal paths of CW-TX and tune different to each other?

Any hint is highly appreciated.

Best regards
Micha, DF4WX

K2 #7488 with all options installed