Hi Blane,
Congratulations on your new-to-you Bighorn and welcome to the Heartland Owners Forum.
The coax from the antenna is combined with the incoming cable TV coax at the signal booster, which is probably located in the bedroom. When watching cable, the signal booster must be OFF, and when watching TV the signal booster must be ON. There's typically a small push/push switch and an indicator light on the signal booster.
You'll need to rotate the crank for the TV antenna to extend it from travel position (don't forget to put it down when leaving). By pulling down on the rotational dial, you can rotate the antenna to face the TV towers. If you're not sure of the direction, see what other campers are doing.
With the antenna up, the signal booster on, and the TV coax input connected to the cable/antenna coax on the wall, you should be almost good to go. You do also usually have to go into the TV menu and set the TV to ANTENNA vs CABLE, and you'll need to do a channel scan so the TV tuner finds the available signals.
If you don't get good reception, try varying the position of the antenna and scan channels again.
If you continue to get poor reception, you may have a coax connection problem. Check for loose connectors on the roof, at the signal booster (inside as well as outside), and at the living room wall. There's also a barrel connector tucked in above the antenna rotational control.
