When you say you can't hear yourself. Do you mean that you have tuned yourself to channel 5 pressed "T" and can't hear yourself speak? If so, does the channel (T) light up in the drop down list when you press the T key? If it does check to see that the mic volume is all the way up. If it doesn't, make sure you have do have it mapped.
If you are trying to use range channel F12 you have to have someone to talk to. You won't hear yourself on range.