From: John De Armond
Subject: Re: Need Special Radio Antenna?
Date: Fri, 25 Feb 2000 17:16:59 EST
Bikerbum Jim wrote:
> The reception on the AM/FM radio in my motorhome is very bad. I can't
> receive any distant stations, even those 50 or so miles away that come
> in very well on my car radio. Fairly strong local stations fade out at
> 10-30 miles. Since my motorhome has a fiberglass body on which the
> antenna is mounted, I'm wondering if I need a special antenna/grounding
> system. The antenna and radio were in the motorhome when I bought it so
> I don't know it the reception has always been this poor. Ideas?
A ground plane will help tremendously, though at the frequencies
involved, a good heavy strap of copper braid from the antenna base
to any nearby chassis metal will do about as much good.
The real trick to good AM reception is to tune the radio to the
antenna. Most all car radios have a "peaking" capacitor somewhere
accessible from the outside that is designed to tune the antenna and
feedline to resonance. Some are accessible through the front panel
but most are on the rear or bottom of the radio near the antenna
connector. most of the time it will be labeled "peak". What you
want to do is to get between stations near the center of the band
and then tweak the peaking adjustment with a non-metallic tuning
screwdriver (from radio shack) until you get the most background
noise. Then tune in a distant station and make a minor adjustment
to make it as strong as possible. it must be a distant station. A
nearby station will be on the automatic level control and you won't
be able to hear any difference. Tune for maximum noise first to
make sure the ALC isn't active. IF what you're interested in
listening is mostly on one end of the band or the other, then tune
there instead of in the center.