so ive been chasing this one for about two weeks now and im starting to go in circles. my 7300 developed this thing where transmitted audio sounds distorted on the other end, people keep telling me i sound like im underwater or there's a kind of gargling thing happening. receive is completely normal, my NR and NB settings havent changed, and the ALC looks fine on the meter - sitting right where it always has been.

i swapped mics already, tried my backup MD-100 and the desk mic both with same result. checked the compression settings, turned processing all the way off, still doing it. ran through the menu and reset the TX equalizer to flat. no change.

weirdest part is it only seems to do it after the radio has been on for maybe 20-30 minutes. if i key up right after powering on it sounds okay apparently, but once it warms up the problem comes back. that thermal clue makes me think something component level but im not sure where to even start poking around on this thing. anyone dealt with something similar or have a theory on what subsystem to look at first

the warm-up behavior is a pretty classic sign of a cap going bad or a solder joint thats marginal. on the 7300 the TX audio path goes through some op-amp stages before it hits the DSP and ive seen a few of these come through the bench where an electrolytic on the mic amp board was the culprit - low ESR at cold but falls apart once it heats up. problem is icom doesnt make those boards super easy to get to.

before you crack it open though, worth checking if the issue shows up on both SSB and AM TX. if its only SSB that narrows it down a bit. also try connecting to a dummy load and recording your own audio off a second receiver nearby, sometimes what people describe as garbling is actually ALC pumping from RF getting back into the audio chain somehow, especially if the coax routing changed recently or something. not saying thats it but rule it out first before assuming its internal.

if you do go inside, the service manual is on radiomanual.net and the RF board isnt too bad to get to once you remove the top cover and the front panel assembly. just dont lose the ground screws along the shield edges, icom loves hiding those.

had something that sounded similar on my 7300 about a year ago, turned out to be the USB audio driver on my PC interfering even when i thought i wasnt using it for audio. the radio was still showing up as a sound device in windows and something was occasionally grabbing it. probably not your issue since you mentioned the desk mic too but just throwing it out there because it drove me nuts for a while before i figured it out.