so ive been lurking on the satellite stuff for a while and finally dragged myself outside last night with my ft-818 and a cheap arrow antenna to try and hit AO-73. i was using gpredict on my laptop for tracking and had the radio split so i could adjust downlink separately from uplink which worked way better than i expected honestly.

i did hear myself once, maybe twice, but the doppler correction is really throwing me off. like i understand the concept - pass coming toward you, frequencies shift up, going away they shift down - but in practice i keep second guessing which direction to chase it. been reading that you adjust the downlink and keep the uplink steady, or is it the other way around? i've seen both written online and now im confused.

also the pass was only like 8 degrees max elevation which probably didnt help. the antenna pointing felt really sloppy at low angles, i was basically just sweeping it around hoping for the best. is there a minimum elevation most people bother trying for with a linear transponder bird like this?

for a linear transponder you generally want to tune the downlink and leave your uplink alone, at least that's the conventional wisdom and it works well in practice. the idea being you find your own signal on the downlink and tweak that to keep it centered, your uplink is just staying put. gpredict can actually drive the radio automatically if you have CAT set up and it'll handle most of the doppler math for you, saves a lot of mental overhead especially on a fast LEO pass.

on the elevation question, yeah 8 degrees is pretty rough. i usually dont even bother setting up for anything under about 15, the signal is just marginal and you spend the whole time fighting the horizon. a 25-30 degree pass is where it starts getting fun. AO-73 is also only running like 150mW on the transponder so link budget is already tight, every degree of elevation helps. keep at it though, once you nail a good overhead pass with a linear bird it kind of rewires your brain about what ham radio can do.

yeah the low elevation passes are rough with a hand-held yagi, i gave up on anything under maybe 12 degrees after a while. your arm gets tired and the geometry is just bad. the arrow is good antenna but you really feel it when the pass is scraping the treeline.

one thing i'd add is watch out for AO-73's operating schedule, it goes into autonomous mode depending on battery state so sometimes you'll show up for a pass and the transponder just isn't on. there's usually some info on amsat's status pages but it can be a little hit or miss. RS-44 might be worth checking out too if you havent, higher orbit so the passes are slower and you get way more time to sort yourself out, doppler is also gentler which helps a lot when youre still getting the hang of it.