Hi Popeye44,
Yes, there is a way to test this. You can tune to yourself on private channel by typing ".radio 5 Popeye44". Remember you have two different transmitters in Aces High - one for whichever channel you are tuned to, and one called "Range", which transmits to everyone who is nearby.
There are different buttons mapped to these functions by default, but I don't recall what the key assignments are.
You may also want to check to make sure your microphone is working within Windows itself.