so ive had my IC-7300 for about two years now and kept reading about the extended TX mod and finally just did it last weekend. its pretty straightforward, just a couple solder points on the main board if you know what youre looking for, nothing crazy. the service manual is your friend here.

anyway the reason i did it was mostly to mess around on some of the MARS/CAP frequencies for a local emcomm group i just joined, not trying to broadcast on AM or anything weird. but while i had it open i also swapped out the stock electret mic element in my HM-219 for an electret from an old Heil element i had laying around. huge difference honestly, people on 40m have been commenting that my audio sounds way better than before. i think the stock mic element in those handmics is just kinda mediocre and Icom knows most people will upgrade anyway.

has anyone else done any other mods to the 7300 thats actually worth doing? ive seen some stuff about the cooling fan mod where you put a quieter fan in but im not sure if thats necessary since mine doesnt run that hot during normal use. also seen chatter about adding an external 10mhz reference input but that seems like a pretty invasive mod for what you get unless youre doing weak signal stuff.

yeah the mic element swap is one of those mods that makes you wonder why you didnt do it sooner. i did the same thing on mine except i used a proper Heil HC-5 capsule wired into a cheap boom mic shell and ran it into the rear ACC jack, totally bypassed the hand mic. takes a little fiddling with the mic gain and the bass/treble settings in the menu but once you dial it in its night and day. people ask me what rig im running because the audio sounds so clean.

on the fan mod — i did it mostly because the stock fan noise was driving me nuts on SSB monitoring sessions. swapped to a Noctua 40mm fan, had to do a little voltage divider since the Noctua wants to run slower than the stock control circuit wants. runs way cooler than it needs to and i can barely hear it. probably overkill but i had the parts.

the 10mhz ref mod i wouldnt bother with unless youre doing FT8 timing critical stuff or something. the TCXO in the 7300 is already pretty decent for most work.

careful with the TX mod if youre not already authorized for those freqs, just saying. i know youre doing it for emcomm and thats fine but ive seen guys do that mod and then wonder why they got a letter from the FCC. not accusing you of anything just worth mentioning since this thread might get read by people who dont have the full context.

i did a different kind of upgrade on my 7300 — added a proper Bonito antenna splitter on the panadapter port so i can feed the raw RF to an SDRplay at the same time. not a hardware mod exactly but it changed how i use the rig completely. being able to see a wide chunk of spectrum on the laptop while operating is really useful for contesting, you can spot openings way faster.