so this is embarrassing but i knocked my 857 off the desk a few weeks ago, it fell maybe 2 feet onto carpet but apparently that was enough to mess something up. at first it seemed fine, powered on okay, received alright, but then i noticed transmit was way off — power output was reading like 8-10 watts on all bands when i had it set to 50, and the ALC was just pegged the whole time i was keyed up. SWR looked fine on a dummy load so it's not the antenna side causing feedback or anything like that.

then last week it started doing this thing where on 40m specifically the display flickers when i transmit, which is just... a new one for me. never seen that before on any rig. receive still seems fine across all bands which is making me think the PA or driver stage took a hit from the drop rather than something in the frontend.

ive got a decent soldering station and a scope so im not completely helpless but i havent done serious rig surgery before, mostly just connector work and stuff like that. was wondering if anyone had seen similar symptoms or had a gut feeling about what component i should be looking at first before i go pulling boards out. dont want to make it worse obviously.

the flickering display on transmit specifically on 40 is interesting — that band is hard on finals in general and if something got jarred loose internally the increased current draw during TX could be causing a marginal solder joint to open up momentarily. i'd start by just reflowing all the connectors between the PA board and the main board before you do anything else, like literally just heat and reflow every connector joint you can access. seen that fix weird post-drop symptoms more than once on Yaesus.

the ALC pegging could be related to the same thing or it could be the ALC line itself picking up garbage from a cracked trace somewhere. if you've got a scope, probe the ALC line while transmitting into your dummy load and see if its actually a clean DC level or if its bouncing around. that'll tell you a lot. also check the driver transistors with a DMM in diode mode while its powered off — if one took a mechanical hit it might read funny even if it isnt completely dead yet.

dropped my 706 once and had low power output too, turned out to be a trimmer cap that had shifted. not saying thats whats happening with yours but physical shock can move things that are supposed to stay put. might be worth doing a TX power alignment if you havent already, theres a procedure in the service manual and Yaesu actually has some of the 857 docs floating around if you search for the SM.