so ive been putting this off for like two years because i was nervous about voiding the warranty but the warranty is long gone at this point so i finally cracked it open and did the transmit mod to open up the frequency coverage a bit. pretty straightforward honestly, just the one diode to clip on the board, took maybe 20 minutes including the time i spent second-guessing myself and looking at the service manual three times.

what i actually wanted to talk about though is what i did after that - i also swapped in a TCXO for the reference oscillator. the stock oscillator on mine was drifting maybe 2-3 hz after warmup which wasnt terrible but i do some weak signal digital stuff and it was bugging me. the replacement unit i sourced off the usual places knocked that down to basically nothing, like sub-hz over an hour of operation which is way more than i need for FT8 or JS8Call.

anyone else done both of these on the same rig? curious if theres anything else worth doing on the 7300 while ive got confidence up and the screwdrivers out. ive seen some stuff about noise floor improvements but havent gone down that rabbit hole yet.

the TCXO upgrade is probably the single best bang for buck mod you can do on that radio, glad you went for it. i did mine about a year ago and same experience, the stock reference is fine for voice and most things but once you care about frequency accuracy it starts to matter.

on the noise floor thing youre probably seeing talk about the front end filter mods - theres a guy who did a pretty detailed writeup on replacing some of the input filtering to reduce some of the birdies the stock radio has on certain bands. i looked into it but honestly for my use case the improvement was marginal enough that i didnt bother. if youre doing serious weak signal stuff maybe worth reading into but dont expect miracles, the SDR architecture in the 7300 is already pretty clean to begin with.

one other thing worth doing if you havent already is just making sure your USB connection is properly isolated from the audio chain, i was getting this weird 60hz hum in waterfall artifacts for months before i figured out it was ground loop coming in through the computer side. not a hardware mod exactly but it made a bigger real-world difference than anything i did to the board.

nice, ive been thinking about the TCXO on mine too. quick question - did you go with the genuine Icom replacement part or one of the aftermarket ones? i've heard mixed things about the third party units and whether the frequency is actually spec'd correctly out of the box.