so ive been trying to work AO-73 for the past couple weeks and i can hear the downlink fine on 145.950 but i cant seem to get my signal through the uplink no matter what i do. running about 5w into a 3el yagi on 435 and a separate 2el for the downlink, both hand-tracked. doppler correction im doing manually by ear which is probably part of the problem but i figured id at least hear myself in the passband occasionally and i just... dont.

one thing i noticed is the transponder seems to be inverting - like i transmit USB on the uplink and i need to receive LSB on the downlink? i read something about this but wasnt sure if that applies to AO-73 specifically or just some of the older birds. also not sure if 5w is even enough or if my uplink antenna is just too small. any hints appreciated, this is way harder than i expected honestly

yeah the inverting transponder thing catches everyone the first time - AO-73 is linear inverting so if you transmit USB on 435 you'll hear yourself as LSB on the 145 downlink, you got that right. most people set their radio up so both VFOs are linked with the doppler offset going opposite directions, but doing it by ear when you're also hand-tracking is a lot to juggle at once.

5w should be plenty if your uplink antenna is actually pointed at the bird. honestly the bigger issue with hand tracking is just keeping up - these things move fast and a 3el on 70cm has enough gain that if you're even a few degrees off you're dropping signal. have you tried just holding the yagi relatively still near AO where you expect it to pass and see if you can hear your own signal at all? sometimes its easier to pick a spot and wait rather than chase it. also check what mode the transponder is in before the pass, sometimes it gets turned off during eclipse and folks spend a whole pass wondering why nobody can hear them including themselves lol

im in basically the same boat, been at this for about a month. what finally helped me was running gpredict on the laptop and having it control the radio via CAT so the doppler gets handled automatically - at least then i can focus on the antenna pointing. still using a handheld yagi but even removing one variable made a huge difference. you might also want to look at SO-50 first just to get the hand-tracking rhythm down since its FM and way easier to confirm youre doing it right before dealing with the linear passband stuff