ok so ive been doing FM sats for about a year now, mostly SO-50 and the occasional ISS pass when its active, and im finally trying to step up to the linear transponder birds. picked up a used FT-817 a few months back specifically for this and been reading everything i can find but im still kinda confused about the whole inverting transponder thing with the doppler correction.

like i understand in theory that on an inverting linear transponder if you tune up on your uplink the downlink goes down, so you have to kind of work against your instincts. but when im actually in the pass trying to track doppler and find my own signal at the same time my brain just melts. been trying on AO-73 and FO-29 and i can hear other stations fine but finding myself in the passband is just chaos right now.

is there a trick to this that clicked for you when you were learning it? also im running a pair of handheld yagis which i know isnt ideal but its what i have. wondering if thats making it harder or if its really just the doppler math thats tripping me up

the inverting transponder thing took me a while too, honestly the way it finally clicked for me was to just forget about doppler correction on the uplink entirely at first and focus on locking onto your downlink. tune around on the 817 receive side until you hear yourself, then work from there. the doppler on the downlink is what matters most for actually hearing the exchange clearly anyway.

what software are you using for tracking? if you arent already using gpredict with a rig control setup that handles the doppler automatically, that changes everything. i was doing it manually for way too long before i set that up and it was just miserable. even a basic laptop running gpredict and a cheap CAT cable to the 817 will take most of the mental load off so you can actually focus on operating. the handheld yagis are fine to learn on, AO-73 has decent link margin when its healthy, youre not the limiting factor there

yeah the dual doppler thing on the linears is genuinely weird at first. one thing that helped me was just working a high elevation pass first, like 60 degrees or above, because the doppler rate is slower near max elevation so you have a little more breathing room to find yourself and make a contact before everything shifts on you. low horizon passes are kind of brutal to learn on.

also FO-29 has been pretty flaky lately, not sure if youve noticed, had a couple passes where the transponder just wasnt on at all so dont get discouraged if you hear nothing on that one sometimes