so i finally got around to setting up for satellite work after talking about it for like two years. running a 2m/70cm cross yagi on an az/el rotor i picked up used, feeding into an ic-9700. everything looks good on paper but actually operating through a linear transponder bird like AO-73 or FO-29 is way harder than i expected and im not sure if its a setup issue or just the learning curve.

the doppler correction is the main thing tripping me up. i have SDR# and also gpredict running but keeping my uplink and downlink both compensated at the same time while actually trying to make a contact is like patting your head and rubbing your stomach. by the time i tune my downlink to hear myself the pass is half over. is there a way to get gpredict to push doppler corrections directly to the 9700 or do most people just do it manually and get used to it? i saw something about hamlib but wasnt sure if that actually works well with the 9700 specifically.

also not sure if my polarization is off — getting signals but they seem weaker than what i see other people reporting. sequencer is on the list but havent built one yet.

yeah hamlib with gpredict is exactly what you want, and it does work with the 9700 though the setup is a little fiddly. you basically run rigctld pointed at the 9700 over USB and then tell gpredict the port and baud rate in the radio interface settings. once that's connected gpredict will push doppler-corrected frequencies to both VFOs automatically — VFO A for downlink, VFO B for uplink — so you can actually focus on the operating instead of chasing frequencies the whole time.

the trick with linear transponders that took me a while to figure out is that you still need to manually find yourself on the downlink first before you transmit much, and keep your uplink power way down. people blast way too much power into these birds and it compresses the transponder for everyone. like 5-10w to a decent yagi is usually plenty, sometimes less. if you can hear the beacon clearly youre probably in good shape signal wise.

polarization loss on LEO passes is real and kind of random depending on the geometry. circular polarization helps a lot but even with linear yagis you can work most passes if the antenna tracking is solid, youll just have some fades. dont sweat it too much until the hamlib stuff is sorted, that'll make a bigger difference right away.

ive been doing LEO sat work for about 3 years and honestly the doppler thing just becomes muscle memory after a while but yeah getting gpredict talking to the radio is the move, dont try to do it manually for linear transponders its brutal. FO-29 is a good one to practice on when its in sunlight, pretty forgiving transponder.

one thing nobody told me starting out — watch your audio drive level on the downlink too. the 9700 has that waterfall and its tempting to just crank the RF gain but you want to keep things clean. also the passes go fast so i usually preload the next two or three in gpredict the night before and just have them queued up.