[RFI] Oh, happy daze!!

Jim Brown jim at audiosystemsgroup.com
Wed Dec 5 20:59:17 EST 2012

On 12/5/2012 5:40 PM, Missouri Guy wrote:
> I was thinking that the inductance might take the "edge" off the voltage spike generated by the fence charger.

Absolutely!  And don't forget about the resistive component. Most 
suppression chokes work by forming a low Q (typically about 0.4) 
parallel resonant circuit with a resonance in the range where 
suppression is needed.  Near resonance the impedance is primarily 
resistive.  From a couple of octaves below resonance down to DC it looks 
mostly inductive, and as you get low enough the inductive reactance goes 
to zero.

I don't know how these fencers work, but I'd start by using something 
like 16-20 turns around a #31 toroid, and if the fencer works, stop 
there.  If it doesn't, pull off turns until it does.

73, Jim K9YC

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