so this has been bugging me for a few weeks now. my 857 started acting weird on 40 meters, putting out maybe 20-25 watts max when everything else is fine — 20m does full 100w, 80m does full 100w, even 6m is fine. 40m just wont go above 25 no matter what i do with the RF power control. ALC looks normal, no weird noises, SWR is flat on a dummy load so its not an antenna thing.

i pulled the top cover and poked around a bit but i dont really know what im looking for. i know these rigs have band-specific driver stages so im wondering if theres a transistor or something on the 40m path that's starting to go. the rig is maybe 8 years old, bought used, no idea what the previous owner did to it. anyone been down this road with an 857?

yeah that 40m low power issue on the 857 is actually more common than youd think. theres a driver transistor — Q1023 or thereabouts depending on revision — that sits in the 40m band pass chain and they can degrade without failing completely. you wont see it as a dead band, just reduced drive getting to the finals. grab the service manual off the usual places and check the bias voltages on the driver stage while its transmitting on 40m, compare to what the manual says. if the bias is off that'll point you at the right component pretty quick.

also worth checking the LPF switching relays for that band, a relay contact that's not fully closing will drop your output without giving you any obvious symptom. spray some deoxit in there if you can get to them.

had almost the exact same thing happen on my 897 which shares a lot of the same guts. turned out to be a cold solder joint on one of the filter board connectors, totally intermittent which made it maddening to find. wasnt even a component failure, just a bad joint. i reflowed the whole area around the 40m LPF section and it came back to full power. worth checking before you start swapping transistors.