so ive been sitting on this for a while but finally pulled the trigger on the mars/cap mod on my FT-857D last weekend. the whole thing took maybe 20 minutes once i figured out which diodes were actually the ones i needed to clip, the service manual is a bit misleading if you're looking at the older revision honestly.

anyway the main reason i did it was i wanted to be able to run some wider bandwidth stuff on digital modes and also just generally have the TX unlock for some emcomm work where we sometimes need to go a bit outside the normal ham bands. the receive side is already pretty wide on this radio which is one of the reasons i bought it used a few years back.

while i was in there i also replaced the internal fan because the original one was starting to make this intermittent grinding noise on high duty cycle stuff like JS8 or any kind of extended digital session. dropped in a slightly higher CFM unit and now the thing runs noticeably cooler on the back panel. probably should have done that mod ages ago honestly.

anyone else done anything interesting to their 857 or 897? curious if the noise floor mods are actually worth the hassle because ive read some pretty mixed things about the IPO and ATT settings versus actually going in and doing component level changes

yeah i did the mars mod on mine probably three years ago, same deal with the diodes being a little confusing to locate if you dont have the right revision of the manual. the thing i'd caution is just making sure you're documenting exactly what you clipped before reassembly because i had a buddy who did it on an 897 and couldn't remember afterward which ones he'd touched and had to trace the whole board again.

on the noise floor question, i messed around with the IF filter mods for a while and honestly the biggest bang for my buck was just putting a decent external preamp on weak signal VHF rather than touching anything internal. the stock preamp in the 857 is fine for HF but for 2m SSB weak signal stuff it's just not great. collins filter swap on SSB is legit though if you do a lot of crowded contest operating, made a real difference in a pileup situation for me.

fan mod is underrated, did the same thing to my IC-7300 even though it doesn't run as hot. just a thing i do now when i get any new radio, the stock fans in most of this japanese gear are adequate but not generous if you know what i mean. FT8 and JS8 will find the thermal limits of anything eventually if you leave it long enough.