[ICOM] 756PROIII intermittent output

[Phil Krichbaum]

    After at least an hour of fairly heavy transmit cycle at 40-50w 
driving an amplifier, my Icom 756POIII rig starts to fluctuate between 
40-50w and 5-10w. Doing things with various controls, changing from CW 
to SSB or RTTY doesn't seem to start or stop this. Sometimes it will 
change power levels within a transmission in either direction. Other 
times it remains at the same level for several transmissions. Sometimes 
it will suddenly behave normally for a period of time before going QRP 
again. Only shutting it off for an extended time seems to stop this. 
Today after working the VK/ZL SSB contest on 160, 80 and 40 it did it 
and I replaced it with another rig and no problem with the FT1000MP 
hooked to the same coax jumper. I had the same problem last weekend 
after several hours of operating RTTY on 80, 40, 20, 15 and 10m. The 
problem became apparent today after a much shorter time than last Sunday 
but I was probably drawing a bit more power to drive the amp on SSB than 
on RTTY.
   I wonder if anyone else knows of a similar problem? I've seen the 
power go to zero and not come back without a trip to the hospital for my 
PROII. It sure sounds like a temperature related deal to me.
   73 Phil N0KE