so ive been chasing LEO sats for a few months now and finally managed to get a decent pass on AO-73 last week. using a Arrow antenna handheld, ft-817 on split vfo, doing the doppler manually which is... an experience. i can hear signals fine on the downlink but by the time i tune to compensate and try to transmit up i feel like im always a little off. either that or everyone else is just way louder than me and im getting stomped.

what im really struggling to figure out is whether my uplink offset is wrong or if its a power thing. running about 2.5w into the Arrow which should be enough right? i know the linear transponders are inverting so LSB up means USB down or whatever, i think i have that right. gpredict is giving me the doppler curves and i manually retune every 30 seconds or so during a pass but its pretty clunky. does anyone actually use gpredict with CAT to do this automatically on the 817? never been able to get that working reliably

yeah 2.5w into an Arrow should be totally fine, i work AO-73 regularly with similar power. the inverting transponder thing trips everyone up at first -- you basically need to keep your downlink signal in the center of the passband by adjusting the uplink, not the downlink. what a lot of people do wrong is they chase their own signal on the wrong VFO and end up all over the place.

for the CAT thing with the 817 and gpredict, i had it working once but it kept dropping the connection. switched to a different rig (705 now) and its much smoother. honestly for handheld Arrow work i just memorize roughly where the doppler is at AOS, mid pass, and LOS and do it by ear. after maybe 10-15 passes it becomes kind of natural. the first few are just chaos, dont stress it

the gpredict CAT with ft-817 -- i gave up on that. the 817 CAT is flaky on a good day and trying to do split doppler correction automatically just never worked for me without constant dropouts. i think some people use hamlib and a virtual serial port splitter to make it work but honestly the manual method isnt that bad once you get used to it. i just tune a bit ahead of where i expect to be and let the pass come to me if that makes sense