[Elecraft] KPA500 power output starts out low, then goes up

[Arie Kleingeld PA3A]

I had the KPA500 PIN diode problem in 2015, and it started on one band 
only. And it did not happen all the time. After a while it became worse 
and more bands were affected.
So based on my experience with my KPA500 #1497, I suggested the PIN 
diode problem as a possiblity.

I wonder what the serial number is of the KPA500 we are talking about, 
and whether it is produced before or after a change in the design(?). 
Anyway, when I presented this problem (how it presented itself on my 
KPA500) in the group and to elecraft support, I never got the right answer.
After basic faultfinding I found that the PIN diode circuit was causing 
the strange behaviour of the linear and then... presto... there was a 
elecraft-mod that I never heard of before.
It contained a few new switching components and some capactiors for one 
of the LP-filters.

After putting those in, problem was solved. My K3 line and me lived 
happy ever after :-).

73

Arie PA3A