so ive been chasing this for a while and finally got a decent pass last night on AO-73 but i feel like im doing the doppler correction wrong or something. im running an FT-818 for downlink and an old IC-290 for uplink, both fed into a cross-yagi setup that my buddy built for me. the tracking software (gpredict) is doing the doppler predictions fine and i have it set to adjust both radios but heres my confusion - when i tune around on the downlink passband to find my own signal, do i just leave the uplink where gpredict has it, or do i need to manually nudge it too?

i found what i think was my signal a couple times but it kept drifting and i wasnt sure if that was me not compensating right or just the sat moving through the pass. the whole linear transponder thing is new to me, ive only ever done FM birds before which is kinda just point and shoot. this feels way more involved. any advice from people who have actually worked it appreciated, im probably overthinking this

the classic confusion with linear transponders - totally get it. so basically the way to think about it: gpredict is giving you a theoretical doppler-corrected frequency but real life is messier than that. the inverting passband on AO-73 means if you tune up on the downlink you actually move down on the uplink, which gpredict handles, but the timing of the correction can lag a little.

what i do is set gpredict to track both, then find my own signal on the downlink first during the early part of the pass when doppler rate is slower. once you hear yourself, you lock on to that downlink freq and just keep tuning the downlink to stay on your own signal - the uplink should more or less follow. if you're hearing yourself drift it's usually the uplink that needs a little manual nudge because the rig control isnt quite keeping up. the 818 is fine for this but i found i had to tweak the CAT polling interval in gpredict, default was too slow for fast passes.

yeah dont sweat the drift too much on a first pass honestly. AO-73 passes go by quick and the first few times you're just trying to hear yourself at all, which you did, so thats already better than a lot of people do starting out. FM birds feel easier but working a linear sat where you can actually hold a CW or SSB contact is so much more satisfying once it clicks. keep at it