Regarding a 10m PSK-31 uplink:
How long were the antennas?
On PCSAT2, the HF system shared the 19" 2m whip. It was a sharp tune, but we got it resonant with a simple LC diplexer.. But then our box was a bigger counterpoise. We were less successful with our 5" cubesat and it's 4' whip. Again, a deployment anomoly cause that experiment to also fail.
It's a bit difficult to do the springy ruler trick in a
cubesat when
they get above 70cm quarter wave unless its a tether :-)
But remember that the uplink stations are using say 25W on 10m. And there is a 14 dB link advantage compared to VHF. And then there is the weak signal performance improvement of PSK-31. So we figured you could give up maybe 10 dB or so in the antenna system, and still have a viable PSK-31 10m uplink.
Also, instead of trying to match the 19" whip to a 10m 50 ohm receiver, if the front end of that receiver was tuned to be a voltage probe, then better antenna efficiency would be possible too?...
Bob, WB4aPR