[RFI] Oh, happy daze!!
k7tjr at msn.com
Wed Dec 5 21:39:41 EST 2012
In a previous life I sold fence chargers and other farm supplies for a
living. A couple things I remember. You are very right in that a good
ground is needed. Some of the application notes suggested using
multiple rods in poor ground areas. Lacking a good ground will cause
the return pulse current to come back through the power cord line
ground making your local grounds and power poles hot with pulse
noise. I would suggest a very good ground and then using the toroid
as suggested by Jim on the power cord to the unit to keep the pulse
current off the local wiring.
In addition, one of the application notes I read years ago suggested
an inductor be placed in the fence line right at the charger output if
radio interference was a problem. Their claim was that it lowered the
speed of the risetime causing less high frequency energy. Right or
wrong I have not looked at that in detail. Their inductor suggested
was about 4 to 5 inches in diameter and about 8 to 9 inches long. It
appeared to have 15 to 20 turns. Remember, the voltage levels we
are talking about here are in the 10 to 20 KV range.
Lee K7TJR OR
>My question is has anyone tried using say, several turns
of wire around a #31 toroid core (or other filter) at the
output of a fence "charger" to reduce/eliminate any
noise from that particular source?
I realize a filter is not going to affect any spark noise from
somewhere out on the line, but just asking about the
filter at the charger output. I was thinking that the inductance
might take the "edge" off the voltage spike generated by the
Any input most welcome!
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