so ive been running my FT-817ND for like six years now and the frequency drift on cold mornings has always bugged me especially on digital modes where being even 20-30hz off can mess up a decode. finally bit the bullet and ordered one of those TCXO-9 replacement units and did the swap last weekend.

install itself wasnt too bad if you've done any SMD work before, main thing is not rushing the reflow on those tiny pads. took me maybe 45 minutes including the time i spent second-guessing myself and looking at the service manual like three times. anyway the difference is actually noticeable — fired it up this morning at about 55 degrees in the shack and it came up rock solid where before id see it wander maybe 50-60hz before settling. wsjtx is a lot happier now.

curious if anyone else has done any other mods on the 817 that are actually worth the time, not just the usual "mod it for mars" nonsense. i've seen some stuff about the PA transistor swap for slightly more output but not sure its worth the risk on a radio this old

yeah the TCXO on those is a genuine improvement, not placebo. i did mine probably 4 years ago and same experience. the stock oscillator on the 817 was never great and yaesu knew it which is why they sold the TCXO-9 as an option in the first place.

as far as other mods, honestly the one thing i'd actually recommend is the internal battery pack upgrade if you're doing any portable work. not a performance thing but swapping to a higher capacity lithium pack makes a real difference in the field. some people do the PA mod you mentioned but from what i've read the gain is marginal like maybe half a watt on a good day and the risk of killing the finals on a radio that's getting harder to find parts for just doesnt seem worth it to me. the thermal management in that radio isnt great to begin with so adding more dissipation seems like asking for trouble eventually.

did you do anything to the RX side at all? ive been thinking about that noise blanker mod where you adjust the threshold pot on the IF board, supposedly helps a lot on 40m with power line noise but I haven't found a really clear writeup on it. the one on eham was from like 2009 and half the photos are dead links lol