[TenTec] Fence Charger Pulses
Mon, 30 Oct 2000 19:10:15 -0800
Ok a couple people have said similiar things to me in emails and you just
touched on something that perhaps I need to make clear. The hot fence has
an internal relay of some sort or switch that goes CLICK every second or so
to turn the current on and off. I'm darn certain it's not a short of any
kind but rather the simple spark of the relay completing the circuit and
radiating through the "antenna" It's like a spark transmitter. The noise
I am getting is not coming in through the mains either but it's pure RF and
I can pick it up on any radio, on ac or otherwise, it's also on the phone
lines. I can run and disconnect the fence and sure enough my net
connection starts speeding up again and I don't get disconnected. Not
quite sure why it's affecting my lines so badly right now though. So I
believe that the unit itself is generating the entire pulse and not a short
somewhere down the line,, given that how would you suggest killing it? By
the way, I've noted some interesting directional characteristics as well of
the fencing with my portable receiver and likewise any time I get closer to
any part of the fence the signal is as loud as though I am standing right
under the unit. The directional tendencies come into play where there is
no fence on two sides of me. I can almost null it out on the receiver by
putting me between the antenna and the nearest section of fence.
Walter Dufrain wrote:
> Welcome to the farm, Dan. We have 3 fence chargers here and yes
> they will all create QRN to telephones, tv's, stereo's, ham rigs,
> scanners and most anything else you can think of that has a detector.
> QST had an article on fence chargers maybe two years ago. The
> article was too brief, at least to me.
> The wire that is the "fence" is a mega antenna for ANY sparks
> that are created from poorly formed wire splices, any of the
> gate hooks (this is a major problem) and a poor ground connection.
> If you have noise, then find the sparks or arcs and you have solved
> the problem. Most of the newer fence chargers are solid state and
> do not have any internal arcing of switch contacts or relays.
> I use an old portable AM radio with a built-in loopstick antenna.
> Tune it to the upper end of the band that is not on a station. If
> you start at the fence charger and walk all the way around the fenced
> area you are going to notice the Hot Spots, which are normally the
> wire splices which are just loosely wrapped instead of being tight.
> As oxidation forms on the aluminum or steel wire outter surface
> you are going to get arcs and sparks. If you will just take the time
> to turn off the charger and go all the way around and re-connect
> the fence wire and make sure every gate hook is cleaned with a
> wire brush, I would bet your problems will be solved.........until
> the next weed or bush or tree limb lays across the electric fence.
> The point that I would like to make is that even though the electric
> fences are handy, they are very very labor intensive to keep a clean
> RF environment. If you still have trouble finding a problem spot,
> then maybe get out there at night and walk the line, look and listen
> for the "tics and arcs".
> Most of the rigs at my QTH are homebrew and do not have noise
> blankers so I like the fences very quite.
> 73 and hope this helps, Walter Dufrain, AG5P.........Wright City, MO
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