In article ,
"OldSailor" wrote:

Our AM/FM radio has severe noise when tuned on the AM band. We have lived
with this, because we mostly listen to FM, but these seem more directional
than the AM stations, so keep fading in & out when at anchor.

Today, I did a test to find the source of the noise. I had suspected it was
the battery charger but this turned out to be wrong. What it is, is a small
computer fan that we use to ventilate the cupboard where the refrig
compressor is located. Turn fan off and noise is gone!

The fan is new and is a typical 3" computer fan except it has two speeds
controlled by temperature.

The refrig unit itself has two fans - a 4" and a 2" and these do not seem to
cause any noise.

I suppose I can change the fan, but is there another way to eliminate the
radio interference?




Well, now, if you really want to eliminate the noise you can do one of
three things.

1. Buy a different fan that doesn't make noise in the MF Radio Spectrum.
They do make them.....
2. See if you can supress the noise coming out of the current fan, with
the appropriarte Ferrite Beads, and ByPass Capacitors, or get one
of the fancy NUMAR or Ormicon Noise Filters for the DC wires
feeding the fan. (wires most likely are acting like an antenna)
3. Get ride of the fan altogether.....or maybe just turn it off while
your listening to the radio.

Bruce in alaska one with years of experience, in noise supression, on
Maritime Mobile Stations.....
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add a 2 before @