so ive had this 897 for about 6 years, picked it up used and it's been solid until maybe two months ago. started noticing my signal reports dropping off and finally got around to putting it on a dummy load with a wattmeter and yeah, it's only pushing maybe 20 watts on HF when it should be doing 100. VHF seems fine actually, or at least closer to spec, haven't measured that as carefully.

already checked the obvious stuff -- PA fuse is good, supply voltage is solid at 13.8, no ALC weirdness on the meter that i can see. the driver board is my next suspect but honestly i haven't cracked one of these open before and im a little nervous about getting into the PA section. anyone dealt with this specific fault on an 897? is there a known weak point i should be looking at first before i start probing around in there

yeah the 897 has a known issue with the driver transistors running hot over time, especially if the previous owner ever ran it without great airflow or pushed it hard on digital modes. the Q1001 and Q1002 area is worth checking -- you can measure the bias voltages on the driver stage without fully pulling the board and that'll at least tell you if you're losing drive before it ever gets to the finals. also worth checking the LPF relays if you havent already, a relay that's not fully switching can kill your output on specific bands without being obvious about it. i'd start there before assuming the PA section itself is toast.

if you have a scope you can trace the drive level through the chain and find exactly where it's falling apart. without one you're kind of guessing but the relay thing is free to check and ive seen it catch people out before.

had almost the exact same symptom on mine a couple years back, turned out to be a cold solder joint on one of the driver board connectors. not even a component failure, just a sketchy joint that got worse over time with heat cycles. reseated the connectors and reflowed a few suspect joints and it came back to full power. probably worth a good visual inspection under magnification before you start swapping transistors.