Trying to bench check a radio without the kind of gear the avionic shop has is asking for trouble. If you do get power on it ok, don't key up the transmitter without having the correct antenna or dummy load connected.
If theres an avionics shop at your airport, or nearby, I doubt it'd cost more than a few dollars for them the check it for you. I've done this several times with Cannon Avionics at Arlington.
Short of that, find a buddy with an airplane that has the same radio. Swap them out and test it that way.
Is there an avionics shop at La Porte?