Hi Driver, welcome back!
The 'T' key is set to transmit on whatever channel radio V (5) is set to. I don't the country channel '2' is valid for radio transmissions, not sure.
You can tune yourself to test your microphone by bringing up the radio buffer with the slash "/" key, then type ".radio 5 GameHandle" i.e. you might type ".radio 5 Driver" in the text buffer. You can then press 'T' to transmit and you should hear yourself. If you don't, make sure you have the correct microphone selected in Game Sounds as Gooss suggested above. If that looks OK but still no sound from your mic, I'd go to Windows Devices and troubleshoot your microphone there.
<S>