so i've been wanting to get into LEO satellite work for a while and last weekend i finally sat down and actually tried it instead of just reading about it. been licensed for about 6 years but always kind of ignored the sat stuff because it seemed like a lot of moving parts to get right all at once.

anyway i set up gpredict on my laptop and had it tracking AO-73 (funcube-1) and the pass was pretty decent, like 65 degrees max elevation so i figured that was a good first shot. running an arrow antenna handheld with my FT-817 and a little HT for the uplink. i know some people do full duplex setups but i was just doing it handheld and monitoring my downlink on a separate SDR dongle through a laptop.

the problem i kept running into was the doppler. i knew i had to manually tune but man it moves faster than i expected especially near AOS and LOS. i was chasing my own signal all over the place and i dont think i ever actually had a clean QSO, heard a couple stations but couldnt tell if i was in the passband or not. gpredict showed my corrected frequency but translating that to what i actually tune on the 817 mid-pass while holding the arrow was... a lot.

is there a trick to managing doppler on a handheld setup like this? and also — how do you tell if you're actually getting into the bird when you cant hear yourself? the linear transponder is inverting right so LSB up USB down or is it the other way around, i always get confused on that.

yeah the doppler thing is really what gets people first time out. AO-73 moves fast enough that if you're not correcting at least every 15-20 seconds near the horizon you're going to drift out of the passband pretty easily. the pass center is where you get a little breather.

for the inverting transponder question — AO-73 uses LSB on the uplink and USB on the downlink, so if you tune your downlink up in frequency, you tune your uplink down. that's the inversion. once it clicks in your head it makes sense but yeah it trips everyone up at first. easiest way to remember: if you hear your signal going higher pitch when you tune down, you're going the wrong way.

hearing yourself is the gold standard for knowing you're in. if you can get even a single speaker or earbud monitoring the SDR downlink while you operate the 817, that feedback loop is huge. some guys preprogram a series of doppler-corrected frequencies into the 817's memory channels before the pass so they can just step through them instead of continuously tuning. clunky but works okay for a casual setup. full duplex is really the answer but i get that it takes more hands and gear than you had going.

im pretty much in the same boat as you, tried my first satellite pass a few months ago and the doppler surprised me too. what helped me was just doing a few passes where i only listened and practiced correcting the doppler on the downlink without even trying to transmit. after a couple passes i had a better feel for how fast it was moving at different points and then when i actually tried to get on i wasn't as panicky about it.

also gpredict has that radio control interface where it can supposedly tune your rig automatically via CAT if your 817 is connected to the laptop — never got it fully working myself but i've seen people say it helps a lot with the doppler tracking, takes one thing off your plate anyway