so ive been chasing this for about a week now and i think i finally narrowed it down but wanted to see if anyone else has run into this. my 7300 started putting out maybe 20-25 watts max on all bands when it should be doing 100. nothing changed that i can think of, didnt drop it, didnt get wet, just one day i noticed the signal reports were terrible and checked with my wattmeter and sure enough something is very wrong.

i checked the obvious stuff first — ALC looked normal on the display, the power setting is definitely at 100%, tried different antennas and feedlines to rule out a reflection issue triggering protection. thermal shutdown was my first thought but it does it even stone cold first thing in the morning before anything heats up.

pulled the lid off and had a look around, nothing obviously fried that i can see, no burnt smell. im starting to wonder if one of the PA transistors is partially gone. anyone dealt with this on a 7300 specifically or have a suggestion where to start poking with a meter before i box it up and send it to the Icom service center.

had almost the exact same thing happen on mine about two years back. turned out to be one of the RD70HVF1 finals was leaky — not dead, just degraded enough to pull the whole stage down. the tricky part is a single bad FET in that push-pull config wont always look obviously wrong on a static resistance check, you kinda need to be watching drain current under actual RF drive to see which one is misbehaving.

before you do anything else though check the bias trim pots if you havent already. on mine one of them had drifted way out and that alone was causing reduced output. its an easy thing to overlook because everything looks fine on the scope until you actually measure idle current on each device. icom has a service manual floating around with the correct idle current specs, worth grabbing if you dont have it. if the bias checks out then yeah youre probably looking at a bad FET and at that point you either swap them yourself if you're comfortable with RF power stages or just send it in. the icom service centers are actually not too bad turnaround wise in my experience.

long shot but did you try a full factory reset? i know it sounds dumb but ive seen weird firmware glitches do strange things to output on these SDR-based rigs. probably not your issue if its consistent across bands but worth 30 seconds before digging into the hardware.