so this has been driving me absolutely nuts for the past couple weeks. my 7300 randomly drops TX power mid-over, like ill be 100 watts one second and then just nothing, not even a carrier, and then it comes back. sometimes its just a split second dip, other times it cuts out for maybe 2-3 seconds and comes back on its own. doesnt seem to matter what band im on, had it happen on 40 and 20 both, and also doesnt seem related to SWR cause the antenna hasnt changed and the meter looks fine right before it happens.

first thing i suspected was the PA finals doing something thermal so i cracked the lid and ran it for a while watching with my infrared thermometer, nothing looks obviously wrong, temps seem normal. also swapped the power cable and checked all the connectors at the back cause i figured maybe a bad connection somewhere, no change. the radio was fine for two years and just started doing this out of nowhere which is what makes me think its not a design issue, something has actually changed or is failing.

anyone dealt with anything like this before? im kind of at a loss for next steps without just throwing it at Icom service which id rather not do if i can help it.

had something similar on a friends 7300 a while back, turned out to be the internal fan connector was loose and the radio was going into thermal protection even though the temps werent actually that high -- the protection circuit was seeing bad data from the sensor not actual heat. pulled the board, reseated the connector and it was fine. probably not exactly your problem but worth checking anything on the PA monitoring side.

also the ALC circuit on those can get flaky, ive read a few posts on eham about people chasing intermittent power issues back to something on the ALC line getting noise on it. if you have a scope its worth watching that line while you TX and see if theres anything weird going on right when it drops. intermittent stuff like this is always a pain to catch but at least the 7300 isnt impossible to work on compared to some of the older rigs.

check the DC power connector at the radio itself, not just the cable. ive seen the barrel connectors on icom gear get a tiny amount of corrosion or just work slightly loose over time and under load they drop enough voltage to trigger protection. 100 watts is pulling like 20 amps and a bad connection that looks fine at low current will show up real fast. put a meter on the terminals at the radio while someone keys it up and watch what the voltage actually does during a dropout. if it dips more than like half a volt under load you found your problem.