so i've been putting this off for like two years but finally got around to doing the MARS/CAP mod on my IC-7300 last weekend. nothing scary, just the usual jumper thing on the board, takes maybe 20 minutes if you're not rushing. but i wanted to post about some stuff i noticed afterward that i dont see mentioned much.

first the obvious — yeah you get the expanded TX coverage which is the whole point. but what i actually found more interesting is the radio just feels a little different on receive in the areas outside the normal ham bands. like i was poking around the 60m area outside the ITU allocations and the noise floor seemed slightly different, not sure if thats psychosomatic or what. probably psychosomatic.

anyway the main reason i did it was for some ARES/EMCOMM stuff where we occasionally need to work on freqs outside the standard allocations under part 97 exceptions. figured i might as well have the capability ready. anyone else done this and messed around with it much? also curious if anyone has done any of the audio mods on the 7300 — ive been looking at the TX audio equalization stuff, supposedly you can get a lot more presence out of the mic chain with some tweaking in the menu but i havent gone down that rabbit hole yet.

did the same mod on mine probably 18 months ago, pretty straightforward yeah. the receive difference you noticed is almost certainly in your head, the front end circuitry doesnt change, its just a firmware/jumper thing that removes the TX lockout. that said i get it, theres always that feeling like something changed when you open the thing up.

on the TX audio — absolutely worth spending time in the menus before you start thinking about hardware changes. the parametric EQ in the 7300 is actually really good and most people just leave everything flat which is kind of a waste. i boosted around 2.5kHz a few db and rolled off a bit below 200Hz and people started commenting on how much better my audio sounded on SSB. took maybe an hour of back and forth with a buddy on the other end giving me reports. way easier than any hardware mod and you can just reset it if you dont like it.

yeah the MARS mod is pretty standard stuff at this point. just make sure you documented what you did somewhere because ive seen guys send radios in for warranty work and forget to mention it and that gets awkward.

the audio rabbit hole on the 7300 is real though, fair warning. i went from menu tweaks to reading about the electret mic element in the HM-219 and ended up swapping it out for a different capsule which was probably overkill. did it sound better? maybe a little. was it worth the saturday i spent on it? debatable. if you do go that route the SM-30 desk mic makes a bigger difference than anything you'll do to the HM-219 just saying.