Electic Antenna ?

It will depend how the antenna is made. Some will stop when they are "up". Some will try to keep going on and on and on. To find a wire to hook to, take off the covers (1/4" nut driver) and look to the back of the off/on volume control. The wire on the back are the power wires-the one that come out the side are the audio wires (leave them alone). With your volt meter probe the power wires with the power off but radio is still plugged in. One wire will have power. The other will go off/on with the radio switch. Thats were you want to tie in a wire for the relay (12 volt radio shack) to turn the antenna on/off