so ive been putting this off for like two years but finally cracked open the 857d last weekend to do the transmit mod and while i had it apart i figured id go ahead and do a few other things. the mars/cap mod itself is dead simple, just the one jumper on the logic board, took me longer to find my smallest screwdriver than to actually do it. but what i really wanted to talk about is the extended rx mod because i feel like nobody mentions that one enough.

after doing both i was picking up stuff in the 108-137 range which is useful when im doing skywarn and want to monitor the air traffic in the area at the same time, not sure why yaesu doesnt just leave that open from the factory honestly. transmit wise i tested it on a dummy load and the power output below 1.8 and above 30 seems a little soft but thats expected i think, its not really designed to be flat across that whole range.

also replaced the electrolytic caps on the PA board while i had it open, a couple of them looked a little bulgy to me and the radio is probably 12 years old at this point so figured why not. havent done a full alignment since i put it back together but its been working fine on all my usual stuff. anybody else done any other worthwhile mods on these? ive seen some stuff about the menu mod to unlock more options but im not sure if thats just a software unlock or if theres actual hardware behind it.

yeah the menu mod is software only, theres a specific button combo at startup that unlocks the extended menu on most firmware versions. on mine it was holding the fast and lock buttons while powering on but it varies by firmware revision so you'll want to look up the exact sequence for whatever version you're running. gives you access to some of the alignment menus and a few extra display options, nothing earth shattering but its nice to have.

good call on the caps by the way. i did mine about a year ago after i noticed the audio was getting a little muddy at higher AF gain settings, turned out one of the caps in the audio section was starting to drift. these radios are old enough now that preventive recapping is just smart maintenance. did you do the internal speaker or just the PA board?

the rx extension is pretty handy, i use mine to listen to NOAA weather on 162 and some of the utility stuff around 136 when im bored on a long portable ops day. one thing to watch though is the sensitivity drops off quite a bit outside the ham bands, its not like using a dedicated wideband receiver obviously. for anything critical id still use a separate scanner but for casual monitoring its fine.

did you mess with the squelch pot at all while you were in there? mine has always had kind of a touchy squelch on 2m where it either totally open or cutting a little too aggressivley, never quite right. been wondering if thats a pot issue or just how these are.