so ive been trying to work AO-73 for about three weeks now and i can hear the downlink fine on 145.950 area, signals are actually pretty decent when the bird is high enough, but i cannot for the life of me get my own signal back out of it. running about 5 watts into a handheld yagi on the uplink around 435.150 and just nothing. i know the transponder is inverting so if im going up on USB im supposed to hear myself on LSB on the downlink side, at least thats what i read.

the tracking is what im really struggling with honestly. im using gpredict on a laptop and it seems accurate enough when i compare it to the passes i can see, but im manually tuning both radios at the same time while also trying to point the antenna and its just chaos. i dont have az/el rotors, just doing it handheld which maybe is the whole problem. doppler on 70cm moves pretty fast near AOS and i feel like i spend half the pass just chasing the frequency and never actually making a contact.

anyone been through this learning curve? is there some trick to the doppler compensation that doesnt require a full automated station setup

yeah the manual tracking thing is rough, been there. what helped me a lot was to just pick a fixed uplink frequency and let the downlink drift rather than trying to chase both at once. set your uplink to something in the middle of the passband, like 435.155 or so, and then only tune your downlink receiver. that cuts your workload basically in half and once you get a feel for how fast the doppler shifts you can make small uplink corrections occasionally without it being total madness.

also 5 watts into a handheld yagi should be enough, people work these birds with a lot less, so i wouldnt assume thats the issue. double check youre actually in the passband though because AO-73s uplink passband isnt super wide and if gpredict has even a small error in the keplerian elements you could be sitting just outside without knowing it. make sure your TLEs are fresh, like updated within the last few days fresh, older elements can throw you off by enough to matter especially on 70cm.

the inverting transponder thing trips everyone up at first. so when you transmit USB on the uplink and you tune higher in frequency, your signal actually moves lower on the downlink. took me an embarassingly long time to fully internalize that. i kept tuning the wrong direction for like two whole passes before it clicked.

one thing i do now is i set gpredict to show me the doppler corrected frequencies and i just write down the start, middle, and end frequencies for a typical pass on a sticky note before i go outside. its not perfect but for a 10 minute pass it gets me close enough that im not totally lost. eventually youll just get a feel for it and your hands kind of know what to do while your brain is thinking about making the contact. its one of those things where the first successful qso makes all the frustration worth it