Radio opens with / key and the alt,ctrl,shift select the sepperate text channels. Voice is F12 for range,basically any friendly in icon range and V channel is "T" to transmit. You can map a key to voice transmit range and another to voice transmit {I have forgotten the proper term} but it's the tunable channel that most squad use to communicate with.
Personally I would reset radio to default and just setup a key or button for both range and the tunable channel in radio box V! Then a simple /+ alt,or ctrl or shift will activate the text channels,as it was designed.
I hope that helps and if you have more question,keep asking!
If you're online I can be found in the training arena most week night between 9pm and 11pm est. I would be more than happy to help with in any way.