so ive been sitting on this mod for probably 8 months now and finally pulled the trigger last weekend. been running the IC-7300 for about two years and generally love it but the rx on the lower HF bands always felt a little soft to me compared to my old TS-590 which i still keep around. anyway i found a few threads over on eham and one over at radioreference pointing to a pretty simple front end mod — basically swapping out one of the input attenuator resistors and tweaking the preamp bias slightly. nothing crazy invasive but you do have to pull the top cover and get in there with a decent soldering iron.

results are honestly better than i expected on 160 and 80m. weak signal stuff that was getting lost in the noise floor is noticeably cleaner now. havent done any proper before/after measurements with the spectrum analyzer yet just going by ear and by what im hearing on the bandscope which isnt exactly scientific i know. did notice it gets a little more susceptible to strong signals nearby so if you live near any AM broadcast towers probably want to think twice or add some filtering upstream.

anyway curious if anyone else has dug into their 7300 or similar SDR-based radios and what mods actually made a real difference vs just being placebo. the AGC tweak mods i see mentioned a lot seem kinda marginal to me but maybe im doing something wrong

the AGC thing on the 7300 is more noticeable on SSB than anything else in my experience — stock AGC is a bit aggressive and if you slow it down a hair you do get better copy on fast fading signals, it's not just placebo but it's also not gonna blow your mind. the front end mod you're describing sounds like the one that's been floating around for a couple years now, i think k9yc wrote something up about it at one point? or maybe it was a different author i don't remember.

my main mod i've done is external bandpass filters on the input, not really a hardware mod but makes a bigger difference than anything inside the radio for me. live about 4 miles from a 50kw AM station and without the filters the front end just gets hammered on 160. with the ICE bandpass set it's like a completely different radio on that band. also threw in a better ref oscillator to tighten up the stability but tbh on a radio that's used daily and stays warm it probably wasnt necessary

did this on mine too, similar experience. one thing i'd add — when you go back in for the spectrum analyzer measurements dont be surprised if the numbers look less impressive than what you're hearing. sensitivity improvements on the low bands are weirdly hard to quantify with MDS measurements because so much of it is about how the radio handles the overall noise environment not just raw noise figure. at least thats what my elmer keeps telling me and it sort of makes sense when you think about it.

also watch the solder joints around that area, the board isnt fun to work on and the pads are small. i lifted one the first time i tried a similar mod on a different radio and spent an afternoon fixing it. go slow and use flux