so this has been bugging me for a couple weeks now. my 7300 is doing something weird where 40m is down to like 30-35 watts max no matter what i set the power to, all other bands are putting out full 100w no problem. i swapped antennas, checked the coax, ran it into a dummy load to rule out the antenna side and still the same thing on 40m. ALC looks a little weird on that band too, kind of jumps around when i key up where on other bands its steady.

the rig isnt throwing any error codes and everything else works fine, audio is good, receive is normal. i pulled the top cover off and dont see anything obviously burnt or leaky caps or anything like that. its about 4 years old and gets used pretty regularly, maybe 3-4 hours a day on average. just wondering if anyone has seen this before or has an idea where to start digging. i dont really want to ship it off to icom if i can avoid it

had almost the exact same thing happen on my 7300 about a year ago. turned out to be one of the driver transistors on the PA board getting flaky — not fully dead but not biased right anymore. the 40m low power thing specifically is a known weak point with a certain batch of these from what i read on the icom reflector. if you have a scope you can probe the gate drive signal going into the finals on that band and see if its actually delivering the right drive level, if the drive looks weak coming out of the driver stage thats probably your culprit. the good news is the repair isnt crazy expensive if you can do the soldering yourself, the bad news is getting the board out of the 7300 is a little annoying but nothing terrible.

i'd double check the PA bias adjustment before pulling anything apart, sometimes these drift over time especially if the rig has been running warm. there's a trimmer on the PA board and icom has a procedure in the service manual for resetting it. the service manual for the 7300 is floating around online if you dont have it. wouldnt take more than 20 minutes to check and might save you from a bigger teardown. also worth making sure your supply voltage is solid under load on 40m, a marginal supply can do weird stuff like this where one band hits the protection circuit threshold before others do just because of how the matching works.