"Ward Silver" <hwardsil@centurytel.net>:
If they are receiving interference on just one or two channels, it's a
harmonic. With a LPF, your troubles should be over.
Often true, but not necessarily...
Moderate overload of the receiver's mixer can cause high order products
that appear to be harmonics, but aren't. For example, 2Frf +/- Flo (3rd
order), 3Frf +/- Flo (4th order), etc. Severe overload will cause blocking
on all channels. Lesser overload causes spurious mixer products at
harmonically related receiver frequencies. Some sets are more prone to
doing this than others.
You may also have harmonic generation from "rusty bolt" connections,
broadband TV preamps, and other non-linear devices. A low-pass filter can't
reduce harmonics generated past its output. Unfortunately, these external
harmonic generators can be hard to track down and eliminate (especially
when the problem source belongs to a neighbor).
73,
--Tim (KR0U)
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