so ive been putting this off forever because honestly i was scared to void the warranty on a radio i paid good money for, but the warranty ran out last year and i figured why not. for anyone who hasnt done this mod, the 857d has a couple of resistors on the main board that limit transmit range to the ham bands only, and pulling them opens up the full TX coverage which is useful if you do any MARS or CAP work, or just want to do some testing across HF without fighting the radio.

the mod itself isnt bad. you need a decent soldering iron with a fine tip and good eyes or a magnifying glass because the components are small. the service manual shows exactly where to look, resistors R1053 and R1054 if i remember right, and you just remove them. took me maybe 20 minutes once i had the case open. the hardest part honestly was getting the thing apart without scratching anything.

after doing it the radio still behaves normally on ham bands, no weirdness with the ALC or anything, power output seems the same. i did notice it will now let you transmit on freqs it wouldnt before which is expected. obviously you still need the right license for whatever you're transmitting on, this isnt a magic ticket to anything, just removes the artificial limitation yaesu put in for the US market.

anyway if anyone has questions about it happy to share what i found. also curious if anyone has done any other mods to the 857, ive seen stuff about the fan mod to make it less noisy and wondering if thats worth the hassle

yeah the fan mod is 100% worth it if the fan noise bugs you at all. i swapped mine out for a noctua NF-A4x10 and the difference is pretty dramatic, thing is almost silent now during normal operation. you have to watch the voltage though because noctua fans are optimized for 12v and the 857 runs the fan at a slightly different voltage in some thermal states - i just wired it straight to 12v with a small resistor inline and it runs a little slower but still does the job even during long transmit sessions. havent had any thermal shutdowns and ive run it pretty hard on digital modes.

on the MARS mod, did you notice any change in receiver performance at all outside the ham bands? im curious how it handles SW broadcast freqs now, my 857 seems a bit deaf down in the lower HF range compared to my older icom but that might just be the antenna situation here

I did the same mod on mine a couple years back, pretty straightforward like you said. One thing i'd add - take pictures before you pull anything apart. I thought i had it memorized and then second guessed myself putting the connectors back and spent like an extra 45 minutes just staring at it making sure i had everything right. Lesson learned the hard way.

The fan mod is on my list too. That fan is genuinely annoying especially in a quiet shack at night doing CW or whatever. My buddy did it with a different fan, a sunon i think, and said it was fine but he mentioned the connector pinout wasnt the same so he had to do a little rewiring. Nothing crazy but worth looking up before you just grab whatever fan fits physically.