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FT-857D receiving fine but TX power dropping to almost nothing — what am I missing

so ive had this 857 for probably 6 years now and it's been solid but the last few weeks i've noticed transmit power is way down. like showing maybe 5-8 watts on a good day when it should be doing 100 on HF. receive seems completely normal, SWR meter looks fine when i key up, no weird noises or smoke obviously, just... no power getting out.

already swapped the coax thinking maybe a connector had corroded inside (we had a wet winter), no change. ran it on a dummy load same result. i did the standard menu checks, mic gain is set right, ALC looks like its barely moving when i speak which honestly might be the clue here but im not sure. i dont have a scope at home, just a basic multimeter and an antenna analyzer.

anyone gone down this road with one of these rigs? im wondering if its a driver stage issue or something with the finals but i really dont want to crack it open if theres something obvious im overlooking first. its out of warranty obviously so im not worried about that, just dont want to make it worse poking around blind.

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ALC barely moving when you're speaking is actually a big clue yeah. on the 857 if the ALC is low it usually means the driver isn't being told to push hard enough, or the driver itself is struggling. first thing i'd do is check your DC supply voltage under load — key up on 40m into the dummy load and watch what the supply voltage does. if its sagging below like 13.5 you might just be starving it and everything else is fine. these rigs are surprisingly sensitive to voltage drop especially if you're running off a switcher that's getting old.

if voltage holds up fine then yeah you're probably looking at driver transistors. the Q1011 area on the PA board is where i'd start looking but honestly without a scope you're kind of guessing. there's a service manual floating around online that has the test point voltages, worth pulling that up before you touch anything inside.

had almost identical symptoms on mine a couple years back, turned out to be a cold solder joint on one of the driver board connectors. the internal ribbon connectors on those rigs can work loose over time especially if the radio's been moved around a lot. i reseated everything i could get to without major disassembly and it came back to life. probably took 20 minutes total. obviously not saying thats definitely your problem but worth trying before digging into the PA section.

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