so ive been on the fence about satellite operation for like two years now and last weekend i finally just did it. borrowed a buddies arrow antenna and used my ft-991a for both uplink and downlink which yeah i know isnt ideal but it was what i had.

managed to hear myself on AO-73 on the third pass i tried which was pretty exciting honestly. the doppler shift thing is weirder in practice than i expected — i kind of understood it conceptually but actually tuning through it while trying to hold the antenna and not lose the satellite was a lot to juggle at once.

my question is about the linear transponder specifically. i was running like 5 watts on the uplink and i could hear myself fine but the signal was pretty weak. is that normal or am i doing something wrong with the power level? i read somewhere that you shouldnt run too much power on linear transponders because of the AGC but i wasnt sure how that actually applies in practice. also is there a good way to know if im actually in the passband or if im just hearing intermod or something else

yeah the AGC thing is real and its one of those things that catches people off guard. the transponder has a fixed power budget basically, so if you blast it with a strong signal you end up compressing everybody else on the transponder not just yourself. general rule of thumb most people use is aim for your downlink signal to be roughly the same level as the transponder beacon if theres one, that way you know youre not being the jerk hogging all the gain.

5 watts through an arrow is probably fine depending on your elevation angle and how the pass went. low elevation passes are rough even with good setup. if you were hearing yourself clearly enough to copy SSB that's actually a decent sign. the way to know if its real signal vs intermod is tune around and see if theres a consistent offset relationship to what youre transmitting — real linear transponder signals will track properly with doppler when you correct for it, intermod usually does weird stuff

i went through the same thing a few months ago, the doppler correction while manually pointing an antenna is genuinely hard at first. i ended up just doing the uplink doppler correction by hand and letting the downlink drift a little rather than trying to tune both at once while also tracking. some people rig up a counterweight system for the arrow to free up a hand but i never bothered. gpredict is what most people use for the tracking and pass prediction side of things if you arent already, it can drive a radio's VFO automatically if you get the CAT setup right which helps a lot with the doppler