[Elecraft] KPA 500

[Alan - G4GNX]

I have a strange fault a couple of times recently, where the SWR starts 
to increase during the time of a single 'over'. I've been using the K3S 
set at 100W out, via the KPA500 (in standby) and the KAT500 tuner, 
without any problem, but after I've switched the linear to Operate and 
driving it to 200W, the SWR creeps up. I don't think it's an antenna 
issue, but a possible heat problem with the KPA500. I watched the 
temperature display on the KPA500 and initially on Standby it shows 
about 38 degrees C. After transmitting at 200W the temperature slowly 
rises above 60 degrees C, but the fan doesn't cut in. Does anyone know 
if this is normal behavior and what temperatures I should expect to see? 
I have tested the fan via the Menu function and it works as expected.

73,

Alan. G4GNX