so this has been driving me nuts for about three weeks now. my 7300 will be running fine, maybe 30 or 40 watts into a dummy load, then suddenly it just drops — like sometimes it goes down to 5 watts for no reason, sometimes it comes back on its own after a few seconds, sometimes i have to cycle power to get it back to normal. no ALC weirdness on the display that i can see, SWR looks fine the whole time.

ive swapped the coax between the rig and the dummy load, tried a different power supply (same issue), checked all the connections on the rear panel. i even ran it with the fan off to see if maybe it was a thermal thing triggering something but that didnt seem to change anything. happened both on 40m and 20m so it doesnt appear to be band specific.

im thinking maybe a bad solder joint somewhere on the PA board but honestly im a little nervous to start poking around inside a radio i paid this much for. has anyone seen this on a 7300 or something similar? wondering if its worth pulling the board or if i should just send it to icom service first.

yeah i had something close to this on an older 706 years back, turned out to be a cracked solder joint right at one of the driver transistors. the symptoms are almost exactly what you're describing — intermittent, not thermal in any obvious way, no clear pattern. the thing with those kinds of joints is they can look fine under a regular light but if you get a loupe on them and flex the board slightly you'll sometimes see it open right up.

on the 7300 specifically though i'd be curious whether the protection circuit is kicking in for some reason. icom has that built in and sometimes it trips on something that isnt immediately obvious from the front panel. there's a service menu you can get into — i forget the exact button combo off the top of my head but it's documented in the full service manual which you can find online — and it'll show you some internal flags that the normal display doesnt. might tell you if the rig thinks something is out of spec even when you dont see it on the ALC meter. worth checking before you start reflowing anything.

does it do it on SSB and CW both or just one mode? i ask because i chased a similar problem on a different rig for way too long and it turned out to be the mic compressor doing something stupid on SSB that i had turned on and forgotten about. probably not your issue since you mentioned the dummy load but just thought id throw it out there.