so ive been putting this off forever but finally got around to doing the transmit mod on my IC-7300 to open up the TX range a bit. nothing crazy, just wanted to be able to hit some of the 60m channels more flexibly and honestly was curious what was under the hood anyway. the mod itself is stupid simple — pull two diodes on the main board, took me maybe 20 minutes including the time i spent second-guessing myself and staring at the board with a flashlight.

what i didnt expect was that after reassembling everything the ALC behavior on my linear felt slightly different. not worse necessarily, just... different. could be my imagination or could be something changed with the drive characteristics when you open the TX range. anyone else noticed anything like that? im not complaining, just curious if theres an actual technical reason for it or if im chasing ghosts. the radio otherwise works great, audio sounds the same, receive hasnt changed at all that i can tell.

also while i had it open i reseated the fan connector because mine would occasionally make a little buzz on certain frequencies and that seems to have fixed it. so overall glad i did it.

the ALC thing is probably real, not your imagination. when the radio is in the stock configuration icom limits more than just frequency in firmware — there are some drive and power curve adjustments that go along with the region settings. once you pull those diodes the radio is basically operating in a less constrained mode and the ALC attack/release timing can behave a little differently especially at the band edges. its not a defect its just that icom tuned things conservatively for the consumer market and the mod basically takes the training wheels off a little. if your linear is happy and youre not seeing weird power fluctuations id just leave it and not overthink it.

and yeah the fan buzz thing is super common on the 7300, mine did the same thing. loose connector resonating with the chassis at certain TX frequencies. one of those annoying little things icom probably should have caught at QC but whatever, easy fix.

i did the same mod on mine probably two years ago and honestly dont remember noticing anything weird with the ALC but i wasnt running a linear at the time so maybe i just wouldnt have seen it. running barefoot into a dummy load for testing everything looked normal on the scope. might be worth logging your ALC voltage over a few QSOs and seeing if theres actually a pattern or if its just random variation day to day, sometimes propagation and band conditions make linears act funky and we blame the radio.