Topband: Electric fences

Earl W Cunningham k6se at
Tue Dec 27 16:14:21 EST 2005

Charles, KZ5K wrote:

"First, what does electric fence RFI noise sound like?  Here, I have a
pulsing noise source (external to my house) when the band is quiet.  It
sounds like pulses of static or white noise.  Pulse duration is about 0.3
sec and the interval between the leading edge of the pulses is just about
1 sec."
I've tracked down numerous electric fence noises over the years at my
rural QTH.  Your pulse noise sounds exactly like a modern electric fence.
 Older fencesare a constant buzzing noise.

"Second, how far away can electric fence noise be heard."
I've had them as far as three miles away.

To track them down, I drive around while listening to the noise on the
car radio to 1700 kHz.  When the noise gets louder I use a transistor
portable AM radio to DF the source.  I usually do this at dusk and, when
close to the source, I can spot where the fence is arcing.  (If the fence
isn't arcing, it normally doesn't cause any RFI.)

In all of the many cases I've tracked down, the arcing was due to one of
three things:

1) Electric fence wire is close to a regular fence wire, arcing to it.

2) Foliage (bushes, grass, etc.) has grown close to the wire, resulting
in arcing.

3) A fence insulator has gone bad, with the spark arcing over the
insulator to ground.

Although it's possible, Iv'e never found a defective fence charger.

Once pinpointed (as I said, you can easily see the spark at dusk),
tactfully tell the fence owner about it.  To gain their cooperation, you
might casually mention that it is a fire hazard.

Hope this helps.

73, de Earl, K6SE

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