Tom, The AM and FM antennas are different. you should not need the boost for AM. Usually the AM antenna is built in. If not it will have a separate connection on the back for the AM Antenna. Most AM separate antennas that I have seen are a rectangle about 4"x5" that looks like a picture frame without anything in the middle frame about 1/2' - 3/4" thick, and 2 wires hanging loose from it. If you think it has an internal antenna, you may want to remove the stereo from the rv and try it outside. If you get reception outside close to the truck reception, then you have a problem with the location in the RV and too much metal around where the stereo is located and need to get a separate antenna. If it does not work outside, and no place to hook up a separate antenna, take it back and get another model.