[Elecraft] K2 10W PA problem

[Guido Tedeschi]

Tom W8JI wrote:
> This is almost certainly thermal drift from heat.
>
> Poor heatsinking of transistors will cause this, so make sure he used 
> the CORRECT very light amount of any heatsink compound and that the 
> transistors are clean underneath and bolted to correct tightness.
>
> Also a very small upward drift in bias voltage will cause this. This 
> can be because of leaky series pass bias transistors or bias pass 
> transistor heating from inadequate heatsinking.
>
Many thanks to Tom and the others: I've noticed that PA transistors are 
not installed perfectly horizontal and it is possible that the 
mechanical contact with the cover is not so good.
This poor heatsinking can explain the drift but, probably, not the 1.2A 
with only 0.5W... Maybe, also the two transistors used for bias voltage 
are not so healty...
Thanks and 73
Guido, ik2bcp