I have a hobbywing V3.1 stock spec and am using it with a Airtronics 92744 receiver. Does the voltage that comes out of receiver stay constant or does it change with battery charge? If it is constant what is the voltage?

Specs:

BEC Output: Linear Mode:6V/3A

Thats it

Thank you, that is what I thought but wasn't sure.

Any idea what the Aux voltage is on a spektrum receiver?

same as on all others