[Amps] OM-2500 strange protect

[la7sl Nils Petter]

Hello !
Our OM-2500HF has developed a strange problem today.
I can switch on,- tune it OK and put it on the air. No problems. BUT
as soon as I take a little brake...say 2-3 minutes QRT
leaving the amp in OPR, it protects as soon as I try to
transmit again. No matter what mode and power level !
It indicates both grid current and plate current to high.
The only way to get it back on the air is to start at 0 drive
and bring it very slowly back up to normal output..then all
is OK until my next break in the pile-up :-)
I have not looked deeper into this problem today,- but will
tomorrow. Just asking for some ideas.  To me it looks as if
the problem is related to thermal conditions in the amp.
Peter