I just installed a TERK HDTV-S to go with my HDTV Tivo HR10-250 unit. When I test the signal strength for the local OTA Hi def stations, the signal bounces from 20-85 and then to 0 over and over again. Anyone have any idea what is going on? I am only 5 miles from the tower. The antenna is a long cable run from the unit, could that be it?