The outside connector is for the incoming cable signal (or satellite, but that requires more work and we'll talk about Cable for now). Connect the coax cable from the "campground" cable wire (or your house) into the external coax connector on the side of the Monty (usually near your entertainment center) to enable the television to receive the cable signal. Then you must also set up the televisions to recognize the incoming cable signal by selecting the TV/Video mode button on the remote or selecting channel 3 or 4 if in TV mode. You must also make sure the booster button is OFF to disable the overhead antenna for the Monty.
Using a satellite receiver requires the connecting/disconnecting. If you need help with that let me know if you need explanation.
There is a schematic going around this forum that shows the typical trailer cable/satellite/airwave cabling. If I find it I will post it, or maybe some other member can beat me to the punch since I am slow at finding and knowing how to post such things. But if you are new to this it might need further explanation, but just ask for help.
Good luck with this.
On edit: I hope this link works. It is the forum topic where DONnANNIE posted the schematic.... scan down a few posts to find it:
http://www.montanaowners.com/forums/...erms=schematic
If you have questions please ask the MOC and we'll try and help.