[Pete Higgins]

toadcat,

Unless it’s right in your backyard I don’t think an AM station will bother you (your VHF/UHF amplifier).

I have a -15.6 dBm UHF TV station & a -13.4 dBm FM station co-located on a mountain 3.5 miles out my back door. My Antennacraft 10 element VHF Yagi and my Antennas Direct 91XG UHF antenna have to point right at them to receive the Los Angeles stations 58 miles away.

When I originally connected those antennas to a Winegard AP-2870 preamplifier the two local stations severely overloaded it. I also tried connecting them through a UVSJ to a Winegard HDP-269 amplifier with similar results. I eventually mast mounted PCT MA2-M cable TV +15 dB, 2.7 dB avg. NF drop amplifiers to both antennas ahead of the UVSJ to preclude the overload. The PCT amplifiers are designed to work in the presence of the numerous and relatively strong signals supplied by cable companies.

Last month I ordered 3 FM band filters from Antennas Direct. I have a Winegard 10 element VHF Yagi feeding the AP-2870 VHF input through one of the FM filters and an 8-Bay Bow Tie feeding the AP-2870 UHF input through a Channel Plus NF-471 55 dB notch filter. Using both of these filters seems to prevent overloading the AP-2870.

As ADTech says:

The C4 and other UHF-only antennas shouldn't be particularly susceptible to FM interference. In any event, that issue is easily handled with FM traps/filters in most circumstances.

My VHF Yagi’s (174- 216 MHz) seem to be pretty responsive to FM band signals (88-108 MHz). I suggested checking for strong local FM stations (http://www.fmfool.com/) so if you decided to add a VHF high antenna and were faced with a situation like me you would have identified it ahead of time.