Electric fence RFI is ruining reception on our VLF lightning receivers, and we need a material to place around neighbors' fence wires to suppress the noise being radiated. Preferably, a split bead, because the fence charger is not readily accessible and everything belongs to someone else.

This is the lowest freq stuff that I've found. It's range is 200 kHz to 30 MHz.


1 Answer 1


I don't think it will work to add suppression to the fence. The fence charger is designed to support heavily reactive loads by generating pulses every second or two. The pulses are formed by dumping the charge of a capacitor bank through a step up transformer. Any additional reactance will be a very minor load delta.

My experience (several miles of e fence here) shows that interference is usually the result of a poor grounding field for the charger or arcing along the circuit e.g. insulators, buried wire, gates, or lightning arrestors. If it is an old "weed burning" charger, it should be replaced for safety and interference sake.

In general, though, ferrite materials are not suitable for low frequency applications. Look at powdered iron materials like (Micrometals) #26 instead.

  • $\begingroup$ Excellent, thank you. I mostly asked this on behalf of other Blitzortung.org participants where there is additional detail about the fence noise. $\endgroup$ Commented Mar 5, 2018 at 20:28
  • $\begingroup$ Are you sure you didn't mean #26? See 1-32 Material 26 Specs and Graphs here. I thought #2 is mostly used for HF amplifier tank circuits. The Micrometals website is down for me. $\endgroup$ Commented Mar 5, 2018 at 21:33
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    $\begingroup$ @MikeWaters Yes, should have been 26. Thanks for catching that. I have edited the answer. $\endgroup$
    – Glenn W9IQ
    Commented Mar 5, 2018 at 23:33

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