so ive been wanting to get into satellite work for a while and finally just decided to do it with whatever i had on hand before buying a bunch of gear. built a cheap tape measure yagi for 2m and using my ft-817 for now. managed to get AO-73 in the log twice this week which was honestly more exciting than i expected given how janky my setup is.

but im having a real hard time with the doppler correction. i know in theory you shift the uplink/downlink opposite directions as the bird comes over but actually doing it while also trying to point the antenna and not trip over the coax is kind of a mess. is there any trick to this or do people just accept that the first minute or two of a pass is basically lost while you figure out where you are in the passband? also gpredict is showing my elevation angles way off compared to what im actually seeing - like it says max elevation 32 degrees but the signal was way stronger when i pointed lower than that. bad TLE maybe?

anyway open to any suggestions, running barefoot on both bands, no preamp yet

yeah the doppler thing just takes practice honestly. what most people do when starting out is just preset a split - like set your downlink VFO to the center of the passband and do most of your doppler correction on the uplink side only, at least for a moderate pass. for AO-73 the total doppler swing is only about plus or minus 3.5 kHz on 2m so it's manageable once you get used to it. the first and last couple minutes are kind of chaotic regardless, most of the usable contacts happen in that 5-10 minute window around max el anyway.

on the TLE thing - yes absolutely could be stale TLEs causing that. grab fresh ones from celestrak or space-track before every session if you can, those things go stale fast especially for low LEO birds. AO-73 is what, maybe 600-ish km altitude so even a day or two of drift in the elements can throw your pointing off noticeably. also worth double checking your grid square and time sync on the computer, ive seen gpredict go weird when the system clock is off by more than a few seconds

dont underestimate how much a preamp would help on the downlink, even a cheap one. i was running barefoot for months and thought i was doing ok and then borrowed an sdr with a lna just to compare and it was kind of humbling how much signal i was leaving on the table. that said plenty of people work AO-73 without one so not saying you need it immediately just something to think about

the pointing thing - ive found that trusting gpredict for azimuth is usually pretty solid but the elevation readout feels off to me too sometimes, not sure if thats an antenna pattern thing or what. like your yagi probably has a pretty wide beamwidth in elevation so you get away with being a bit low