so ive been wanting to get into LEO satellite work for a while now and last weekend i finally just went for it. borrowed a pair of cross-yagis from a club buddy and set up in the backyard with my FT-818 and an old laptop running gpredict. the pass looked decent on paper, maybe 6-7 minutes, elevation peaked around 52 degrees which i figured would be plenty of time.

the problem is i completely underestimated how fast you have to tune on the linear transponder. AO-73 has that inverting transponder so when youre doppler correcting on the uplink it goes the opposite direction from the downlink and my brain just could not keep up in real time. i kept hearing my own signal wandering all over the place. got one contact, barely, some guy in Ohio who i think was also struggling because his audio was all over the place too.

i know people do this with just a single dual band radio and manual tuning and i honestly dont know how. is there some trick to it or do you basically just have to run SDR on the downlink and have a separate radio for the uplink so you can at least hear yourself? or does it just take a bunch of passes before your hands know what to do automatically

yeah the inverting transponder thing gets everyone at first. the way i finally got it to click was to basically stop thinking about the uplink frequency and just chase the downlink. park your downlink on your signal and stop touching it, then only move the uplink to correct for doppler on that side. it sounds backwards but once you lock onto yourself on the downlink you realize when you need to nudge the uplink up or down.

the other thing that helped me a lot was doing a few passes just listening, not even trying to transmit. just track with gpredict and watch how much the beacon moves across a full pass. gives you a feel for the rate of change before you're also trying to point an antenna and find contacts at the same time. 52 degree pass is actually a lot to handle when youre just starting out, a lower elevation pass is weirdly easier because things move slower.

I run an IC-9700 with the satellite mode which handles the doppler split automatically and honestly even with that it still catches me off guard sometimes when the pass is coming up fast. one contact on your first real attempt with manual tuning is not bad at all, most people i know just heard nothing the first few times and gave up. the Ohio guy was probably just as lost as you lol