so this has been driving me nuts for the past couple weeks. picked up a used 7300 from a local ham who said it was 'working fine' but needed a cleaning. well it powers on, receives perfectly, but i cannot get more than about 20 watts out of it on any band. tried it on 40, 20, 10, 2m through a transverter, same deal everywhere. the power meter on the rig itself agrees with my external wattmeter so at least the display isnt lying to me.

ive already checked the obvious stuff - ALC is not pegged, the RF power knob is all the way up, not in low power mode, mic gain is set normal. did the touch screen calibration thing just in case. nothing changed. also noticed the finals dont get particularly warm even when transmitting which makes me think its not a thermal protection thing kicking in.

before i crack it open and start poking around, has anyone seen this specific symptom? wondering if theres a driver stage issue or maybe something upstream of the finals. or honestly could just be a bad PA board. really dont want to send it to Icom if i can help it, their turnaround times are brutal right now.

had almost the exact same thing happen with mine about a year ago, different cause though. first thing i'd check is whether the ALC line is getting a weird voltage from somewhere even when it shouldnt be - there's been a few cases where a leaky cap on the ALC circuit was essentially clamping output without the meter showing anything obvious. you can probe the ALC input on the PA board with a meter while transmitting and see if its sitting at some unexpected voltage.

also worth checking is whether the bias on the final transistors is set correctly. if someone got in there before you and tweaked stuff they shouldnt have, bias could be way off and that'll absolutely kill your output without necessarily killing the radio. the service manual has the bias adjustment procedure and its not too bad if you have a current probe or can improvise one. the 7300 finals are RD70HVF1s if i remember right, fairly robust devices, probably not blown but could be limping.

honestly the driver stage is worth looking at too before you go replacing finals. a weak driver will cap your output in exactly this way and driver transistors are way cheaper to replace. what does your ALC meter show when you key up?

dont overlook the menu settings before tearing into it hardware wise. theres a setting in the set menu under tx/rx that sometimes gets reset or corrupted, specifically the RF power ceiling thing. also check if the previous owner maybe had it set up for some kind of external amp and had it configured to limit drive. i know it sounds dumb but ive been burned by that before, spent an afternoon with a scope and it was a menu setting the whole time. embarrassing.