[TowerTalk] Fwd: Polarity question..on a dipole
HansLG at aol.com
HansLG at aol.com
Sat Apr 1 18:01:45 EDT 2017
I don't think the RF power from an electric fence is enough to even get a
measurable temperature increase on those insulators. The voltage is high but
the duration is short.
I just wonder if you put an LP filter on the output on the pulse generator
that would help the annoying pulse interference. Yes, the LP filter has to
be designed for the high voltage, that is, the capacitors has to be of a
high voltage type. If you can increase the rise and fall time of the pulse
you would get less RF to leave the wires. Just an idea.
Hans - N2JFS
In a message dated 4/1/2017 9:22:52 A.M. Eastern Daylight Time,
patrick_g at windstream.net writes:
All the fence chargers I have seen have a pulsed output. I have not
examined the waveform of their pulses with an o'scope but suspect the
pulses contain significant RF since I can clearly hear them on my Flex
5000A on multiple bands. A minor annoyance listening to an approximate
1/sec noise burst but not enough to motivate me to walk out to the barn
to shut it down then back again to turn it back on, especially if it is
Luckily my antennas are not close to any of the electric fence spans.
Just guessing but if the RF component of the pulses were to be
penetrating the plastic insulating tubing, i.e. shorting out to grounded
metal in contact with the tubes OD or if the RF were getting through the
tubing to the damp earth where it is buried I would have thought that
would have selectively attenuated the RF before it was propagated down
the fence wire and radiated where my antennas could pick it up.
The fence charger itself is inside a well grounded all metal building.
If the charger is running but not connected to the output wire the radio
does not detect pulses so any noise emitted by the charger itself is
contained within the building and additionally does not get to the shack
via the AC wiring as no pulses are heard if the output is not connected
to the distribution system/fence wires.
The tubing is cheap so I would give it a try before writing it off if I
needed to insulate a wire antenna from something.
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