The jack below the CH3/4 switch is for outputing to a tv that does not have seperate video inputs. It is 480i (as it is standard TV). The jack above it is for passthrough. When the box is turned off, it routes the input to the output so you can use your tv's tuner for locals via an antenna, or cable, or from a VCR or something. I am using the RF out on my tv in my bedroom, and the quality is outstanding. I seriously doubt it has enough strength to broadcast, even across a room, via an antenna. I would just recommend running some additional coax to the other rooms, THIS would probably work for a few tv's via a splitter. It will depend as much on the quality of the TV's tuner as it will on the signal strength.