so this has been driving me absolutely nuts for the past three weeks. my IC-7300 started dropping TX intermittently, like ill be mid-qso and the power just falls off a cliff. not slowly, just gone. rx is totally fine the whole time, swr doesnt spike or anything weird. it comes back after maybe 30-60 seconds and then works perfectly for a while before doing it again.

at first i thought it was thermal, like maybe something was getting hot and throttling, but ive been watching the finals temp on the display and its nowhere near the threshold. ambient temp in the shack is fine too. ive also ruled out the power supply because i swapped in my backup and same thing happens.

checked the fan and its spinning properly. connector on the back of the radio seems solid. the weird part is it seems to happen more on 40m than anywhere else but i cant be 100% sure, maybe im just on 40 more often. no error codes, nothing in the menus looks off. anyone dealt with something like this before or have a starting point for diagnosis?

had something similar on my 7300 maybe a year ago. turned out to be a cold solder joint on one of the driver board connectors, not the finals themselves. the symptom that matched for me was that it was totally fine on rx and would come back after a rest period. i actually found it by very gently flexing the chassis while it was in TX and i could make it drop on command which at least confirmed it was mechanical/thermal expansion related rather than a component failure.

icom's service manual for the 7300 is floating around online and the board layout is actually pretty approachable if you're comfortable with a soldering iron. id check the connectors between the RF unit and the main board first before assuming its a component. could also be worth checking ALC voltage with a scope if you have one, sometimes a drifting ALC circuit can cause exactly this behavior and its not always obvious from the front panel.

is your mic gain cranked up? i know it sounds basic but i had a weird tx drop issue that turned out to be ALC clipping hard and the radio basically protecting itself. wasnt quite the same as yours but worth checking. also the 7300 has that TX inhibit function, any chance something external is triggering it?