[RFI] A RF Quiet Electric Fencer needed

[Jim Brown]

On Mon, 5 Jan 2009 15:45:24 -0500 (EST), ROBERT MARCH wrote:

> wave shaping. 

That's exactly right. The relative strength of higher order 
harmonics (that's us) is directly proportional to the rise time. 

I don't know anything about electric fence circuitry, but if the 
major concern is strength of those harmonics in the ham bands, it 
seems to me that a ferrite choke wound so that it is tuned to those 
ham bands would do the job. That's because a ferrite choke near its 
resonance is highly resistive, NOT inductive. It's only inductive 
well below resonance. 

On the other hand, the best broadband ferrite chokes yield 
resistance values in the 5K - 10K ohm range. Depending on the 
impedance of the circuit that's producing the current that's doing 
the radiating, that may not be enough resistance. For example, the 
radiation could be from the fence wire, or it could be from an 
internal current loop in the electronics package. 

Tree -- where in the circuit did you put your choke?   

73,

Jim K9YC