ok so ive been licensed for about 3 years, mostly HF stuff, but i finally got curious about working sats after hearing a guy at my club talk about it. got myself a decent yagi setup for 2m/70cm, dual band radio that can do full duplex, and downloaded Gpredict which seems to work fine for tracking.

my problem is im just not hearing anything. i pointed at AO-73 during a pass last week and got nothing. i mean i could hear some noise floor changes but nothing i'd call a signal. the pass was pretty decent, something like 25 degrees max elevation, so it wasnt a super low one. am i supposed to hear a beacon first and work from there or is there a specific dial freq i need to be watching. ive read like four different pages and they all say slightly different things about the uplink/downlink splits.

also gpredict is showing the doppler corrected freqs but do i need to be manually chasing that or does it actually control the radio somehow. i set it up to talk to the radio over CAT but not sure its actually doing anything

AO-73 is telemetry only mode most of the time - it only opens the linear transponder during weekends or when the batteries are healthy enough, and even then it's not guaranteed. you might want to check amsat's status page before a pass so you're not just staring at a closed transponder. that could be your whole problem right there.

for the doppler, yeah gpredict can drive the radio if you have the CAT connection set up right. go into the radio control interface and make sure you've got the right device and baud rate, then when you hit track it should follow the corrected freqs automatically. test it on the ground first, tune to like 145.000 and watch if gpredict moves the dial when you drag the doppler slider manually. if it does you're connected. the doppler shift on a 70cm downlink can be several kHz so chasing it by hand is doable but annoying, especially on a short low pass.

FO-29 has been cooperative lately if you want to try a different bird, and SO-50 is FM which is easier for a first contact even though the transponder experience is different.

yeah what he said about AO-73, i wasted probably 6 passes before someone told me it wasnt even in transponder mode lol. the amsat status page is kinda ugly but its got the info you need. also dont underestimate how much antenna pointing matters - 25 degrees isnt bad but if your azimuth was off by even 20 degrees you could miss it entirely depending on the satellite footprint. did you have a rotor or were you hand tracking? i do hand tracking still and it works but you gotta be pretty committed to spinning the yagi and not lose your place