so ive been sitting on doing the transmit mod on my IC-7300 for probably six months now, kept putting it off because honestly it seemed like more trouble than it was worth and i didnt want to void anything. finally just did it last weekend after a buddy showed me how straightforward it actually is. just a jumper removal on the board, took maybe 20 minutes including the time i spent second guessing myself.

the reason i even bothered is i do some MARS work occasionally and needed the extended TX coverage below the ham bands. not looking to do anything sketchy, just practical stuff. anyway the mod itself went fine but what surprised me is the audio seemed... marginally better? or maybe im imagining it. somebody else told me that happens sometimes with the filtering changes but i dont know if thats actually a thing or placebo. the rig does run a tiny bit warmer when i push it on extended freqs but nothing alarming on the fan.

anyone else done this and messed around with the TX EQ settings after? im running a Heil PR-40 through a Behringer preamp into the mic input and trying to dial in the audio response now that the mod is done. feels like the passband is a little different but i could just be overthinking it.

yeah the audio thing is probably in your head honestly, the mod doesnt touch anything in the audio chain, its just freeing up the TX range limiter that icom puts in at the firmware/hardware level. that said the 7300 EQ is actually pretty capable if you dig into the ACC settings and mess with the bass/treble rolloff. i spent a good afternoon getting mine dialed with a similar mic setup, ended up cutting some of the low mids around 300hz because it was getting muddy on SSB. worth running it by a buddy on the air and having them give you honest feedback rather than trusting the monitor.

the heat thing is real btw if youre pushing duty cycle on digital modes at extended freqs, just keep an eye on it. on SSB voice youre probably fine.

I did the same mod about two years ago for MARS, no issues since. One thing I'll add — after you do that mod it's worth going back through the menu and double checking your power limits are set right for each band because mine defaulted to something weird on a couple of the lower freq ranges, can't remember exactly what but it was putting out more than i expected on one segment. minor thing but worth a look if you haven't already.