so ive been wanting to try satellite work for a while and finally got a setup going, using an FT-818 and a pair of arrow antennas, one for 2m uplink and one for 70cm downlink on AO-73. managed to hear myself a couple times which felt insane honestly

but heres what i dont really get — everyone says you have to constantly tune for doppler but when i try to do it manually during the pass i always seem to be chasing my own signal around and by the time i retune i've already moved again. is there some trick to this or am i just not fast enough yet. i tried the gpredict approach where you set it up to correct automatically but my radio isnt supported and i couldnt figure out the CAT control side of things

also the inverting transponder thing still messes with me. so if i tune my uplink higher my downlink goes lower, right? i kept forgetting this mid-pass and making it worse. anyone have a simple way to think about this that actually sticks in your head

yeah the inverting transponder thing trips everyone up at first, took me a few passes before it clicked. the way i think about it — imagine the transponder passband is a fixed window, and your signal moves within it. if you slide your uplink frequency up, you're pushing toward the top edge of the passband, which maps to the lower end on the downlink side. once that visual stuck in my head it made more sense

for doppler correction manually, what a lot of guys do is just pre-tune the downlink to where it'll be at AOS, then as the pass progresses you're mostly chasing the downlink and leaving the uplink more or less alone until you really need to adjust. on a short 10 minute pass you wont have time to be fiddling with both radios constantly anyway. get the downlink locked first, everything else follows. if you can get CAT working eventually it makes life way easier but plenty of people work sats just fine without it, just takes a bit of feel for how fast the doppler shifts on a high vs low elevation pass

im in pretty much the same boat as you, been doing AO-73 passes for about 3 months. what helped me was just printing out the doppler shift table for 435 and 145 MHz and taping it to my desk so i could see roughly where i should be at different points in the pass. crude but it worked until i got the CAT stuff sorted out

also dont stress too much about hearing yourself on the first few passes, even experienced guys lose themselves in the pileup sometimes. the main thing is getting the antenna tracking smooth, everything else kind of falls into place once you're not fighting the AOS and LOS angles