so ive been putting off the mars/cap mod on my FT-857D for like two years because honestly the inside of that radio is terrifying to look at. finally sat down with it last weekend and got it done, transmits on all the out of band freqs i needed for some EMCOMM stuff our group has been working on.

the mod itself is just a couple diodes on the main board, nothing crazy, but the disassembly is where i lost like 45 minutes because the RF board has this one ribbon cable that is NOT obvious how to release. i ended up looking at three different youtube videos before i figured out there's a little locking tab you push down not up. would have been nice if anyone mentioned that in the written guides.

anyway while i had it open i also went ahead and replaced the stock cooling fan with a quieter noctua-style 40mm fan because the original whines like crazy on digital modes when it spins up. big improvement honestly. had to print a little adapter bracket but ran it off the same fan header, works fine.

one thing im still thinking about is the IF shift mod i saw on one of the german ham sites, supposedly sharpens up the filtering response a bit. anyone actually done that on an 857 or similar radio? feels like it might be more trouble than its worth but im curious if there's a real audible difference.

the ribbon cable thing on the 857 got me too, spent a good 20 minutes on that the first time. once you know the trick its obvious but yeah none of the guides bother to mention it. the japanese service manual actually shows it clearly but good luck finding a clean copy of that.

on the IF mod — i looked into it a while back and from what i could find most of the guys who did it said the difference was pretty subtle unless you're running the radio with narrow filters already. the 857 without the optional collins filters is kinda already compromised in the selectivity department so adding the mod on top of stock filters might not get you much. if you havent already the SSB filter is probably a bigger bang for the buck before messing with the IF circuit.

fan swap is a good call, been meaning to do that on mine for ages. which noctua did you end up using, the NF-A4x10 or one of the thinner ones? i measured the cavity and wasnt sure if 10mm depth would clear everything.