so i've been putting this off forever but last weekend i finally opened up the 857d to do the mars/cap mod so i can tx outside the ham bands for some emcomm stuff our group does. pretty straightforward once you find the right jumper, there's a couple different versions floating around depending on firmware revision so make sure you're looking at the right diagram for your unit or you'll be confused like i was for about 20 minutes.

while i had it open i also resoldered a couple joints on the PA board that were looking sketchy, one of them was clearly a cold solder from the factory. no idea if it was causing any issues but it looked bad so i fixed it. also cleaned up the fan and reapplied thermal compound on the finals since i was in there anyway, running a bit cooler now i think but hard to say for sure without doing a proper before/after.

anyone else done any other worthwhile mods to the 857d? ive seen some stuff about the DSP filter settings and tweaking the IF shift but never dug into it. also thinking about the noise blanker mod but not sure if thats worth it for HF mostly.

yeah the cold solder joints on those are pretty common, yaesu QC on that era of radio wasnt exactly stellar. i found two on mine when i did basically the same thing a few years back.

the DSP tweaks are worth doing imo, theres a menu setting that lets you narrow the SSB filter down tighter than the default and it makes a noticeable difference on crowded 40m. not a hardware mod really just getting into the deeper menu levels. also i added an external speaker with a better driver and that honestly made more difference to my day-to-day operating than anything else i did hardware-wise, the internal speaker on those is genuinely terrible.

for HF i wouldnt bother with the noise blanker mod, the stock one works fine for most stuff. where it falls apart is on strong pulse noise like power line interference and even the mod doesnt totally solve that, you're better off just using a bandpass filter or moving bands honestly.

nice work on the thermal compound, i always forget to do that kind of preventive stuff until something actually goes wrong. whats the temp difference you're seeing approximately, like in terms of the heat on the case or are you measuring the finals directly?