dennisbrandi, Here is what Winegard says about the plate,
"Twelve volt DC power supply for Roadstar or Sensar antennas in a flush mount wall plate. Includes on/off switch with LED, 12V DC receptacle, input for cable or antenna, built in splitter for second TV and second F jack for an outside TV source such as cable".
There is a second wall plate that looks the same but includes an amplifier for 75Ohm Winegard non-amplified antennas.
I use the receptacle for my 12V DC TV. It is always hot, even when the antenna is turned off.
Hope this helps.