so this has been bugging me for probably three weeks now and i cant figure it out. got my 7300 about two years ago used, ran great until recently. what happens is ill be in a qso or even just tuning around and mid-transmission the power just drops, like from 100w down to maybe 10-15w for a few seconds then comes back up. sometimes it stays low and i have to release the ptt and key back up. ALC looks weird when it happens, kinda jumps around.

at first i thought it was the coax but ive swapped that out twice now and same deal. swr on the antenna is fine, checked it with the external meter. the radio doesnt throw any errors, no PA fault or anything on screen. temps seem okay too, fan kicks on like normal. i did the recalibration thing in the service menu a while back but that was before this started happening.

anyone dealt with this before or have a clue where to start? im not opposed to cracking it open but idc want to make it worse

had something similar on mine a while back, turned out to be the finals starting to go. not completely dead but thermally intermittent — they'd get warm and the bias would drift. the giveaway for me was it happened more often the longer i transmitted, like after 30-40 seconds of solid carrier it'd drop out but a short over was fine. does yours do it more on longer overs or is it random regardless of how long youve been keyed?

also worth checking the connection on the PA board itself, theres a ribbon cable in there that can work itself loose especially if the radio moved around at all. icom's service manual is floating around online and the PA section is pretty well documented. if you're not comfortable digging in, a lot of repair shops can scope the bias voltage while its transmitting and that'll tell you pretty quick if the transistors are on their way out.

check your power supply before you go pulling the radio apart. i know you said coax but did you actually measure the supply voltage under load? a lot of these symptoms people blame on the rig turn out to be a switcher thats sagging when the current demand spikes. 7300 can pull close to 20A at full power and if your supply is marginal or a connection is corroded somewhere on the DC side it'll do exactly what youre describing. seen it more than once where guys chase the radio forever and its the powerpole connector or even the anderson on the supply thats got some resistance built up.