so ive been fighting this thing for about three weeks now and im starting to lose my mind. the radio will be running fine, like ill be in a qso on 40m and maybe 20-30 minutes in the power output just drops. not to zero, but from like 100w down to maybe 15-20w and it stays there until i cycle the power off and back on. sometimes it comes back fine, sometimes it takes a few cycles.

at first i thought it was heat related because it seemed to happen more in the afternoon but ive done some testing and it happened this morning too when the shack was pretty cool. ALC looks normal on the display before it drops, and the SWR on the antenna side is fine, been running that dipole for years with no issues.

havent opened it up yet because its still under warranty but warranties almost up so im thinking about digging in. anyone else seen this or have a starting point for diagnosis? feels like it could be the PA board or maybe something thermal even if it isnt strictly temperature triggered

I had something similar with my 7300 about a year after I got it. turned out to be a cold solder joint on the PA board, one of the driver transistor pins. wasnt obvious visually, had to use a magnifier and even then it was a tiny hairline crack. reflowed it and its been solid since. might be worth pulling the covers and having a close look before you send it anywhere, especially if the warranty is basically done. the board layout is pretty accessible once you get the lid off, just take your time with the connectors.

that said yours sounds a bit different because mine would drop and not recover at all, not bounce back on power cycle. could also be the temperature protection circuit getting a false trigger somehow, theres a thermistor in there that feeds back to the processor. if its reading high for some reason the rig will throttle back even if the PA isnt actually hot.

yeah check the fan is actually spinning and not just starting to seize up, had a completely unrelated radio do something like this and the fan was the culprit. even if the shack is cool the rig itself can get hot if air isnt moving through it properly.