[Elecraft] rf power fluctuations

[Frank DL4KQ]

G`day,


I`m running a K2 + EC2(KAT100/KPA100), fully loaded, actual fw`s, which seemed to work fine.
But driving an external linear amplifier (tune situation) I noticed inacceptable rf output fluctuations of the KPA100.
(measured on antenna as well as on dummy-load)


K2 (alone): obviously no output fluctuations
K2+KPA100 (independant of KAT100 settings: bypass or auto mode): 
1. jumping output fluctuations of 10 to 15 W on all bands 
2. height of fluctuation nearly independant of K2 power knob setting; f.e. 10 W jumps at 30 W as on 50 W or any other driver setting.
3. fluctuation depends on K2 power knob setting, there exist ranges with and without fluctuation (on same band), obviously different ranges for different bands.


Asked a friend to come along with his K2+EC2 (also fully loaded, actual fw`s) for test changing of components.
But his K2+EC2 showed same behaviour.
Btw, another K2/100 + KAT100 (all but KX60V options) showed same behaviour but fluctuation was less (max. 8 W).

10-15 W jumps are a bit "much" ...   :-((

Any ideas?

Frank, DL4KQ