so i went ahead and did the Collins filter mod on my 7300 a few months back, basically swapping out the stock roofing filter situation for better adjacent channel rejection. found the writeup on eham and a couple youtube vids that made it look pretty straightforward. and i mean, it mostly was, except i think i either got a bad filter or i nicked something on the board because now i'm getting this weird artifact around 7.150 that wasn't there before. like a faint birdies situation, hard to describe. doesnt show up on the waterfall unless im really cranked up on the RF gain.

anyway the actual performance improvement for contesting was real, i could tell immediately on a crowded 40m band. pulling out signals that were just getting buried before. so the mod itself works, im not saying dont do it. just wondering if anyone else ran into weird birdies after doing board-level work on these rigs. makes me wonder if i introduced some grounding issue or maybe there was a solder bridge i missed somewhere. going to pull the cover again this weekend and have another look.

also while im in there thinking about doing the TX mod to open up the transmit range, not for anything sketchy just want to be able to use it on 60m without the weird power dropoff. anyone done both at the same time or have opinions on doing one before the other?

the birdie thing is almost certainly a grounding issue or you've got a tiny solder bridge you missed. happened to me on a 7000 years ago after i replaced a cap near the IF stage, took me forever to find it because it was only visible under magnification. get yourself a loupe or a decent USB microscope if you dont have one, totally worth it for this kind of work. the 7300 board is dense and icom doesn't exactly leave you a ton of margin for error in there.

as for doing both mods at the same time, id honestly sort the birdie problem first before you go touching anything else. no point compounding the troubleshooting. the TX range mod is pretty benign on the 7300 and there are a ton of documented methods but clean up what you broke first, then expand from there.

yeah the 60m power dropoff thing is a known annoyance, some guys just run reduced power on that band and call it a day but if youre doing board work anyway makes sense to address it. i did the TX mod on mine like two years ago and it's been fine. never touched the roofing filter though, honestly my ears arent good enough anymore to care about that level of adjacent rejection haha. getting old is rough on the hobby in ways nobody warns you about.