Mystery solved. The top connection is not connected to anything!! There are 3 inputs to the bottom coaxial with 2 being hooked up, one from the cable on the street side and the other coming from the antenna. There is a third one that is unhooked on the lower unit. It appears that all 3 on the lower are powered and if I recall the power has no effect on the cable input as I leave mine plugged into the lower and have used it both on cable and air, I just have to program the tv for which input I'm using. There is 12v going there to power the antenna booster. Jon is right, it is a tight fit and I'm not sure if I can pull it entirely out to unhook and reconnect another one. It is a Winegard unit so it should be compatible with the 12v model. This would allow me to plug tv and antenna into one unit and free up my second 12v below the tv for cell phone charging.
never in doubt, often wrong