[RFI] Snap-on RFI suppression core size vs cable size

N1BUG paul at n1bug.com
Sun Aug 20 16:27:24 EDT 2017

I suspect this is a stupid question but I am not finding a concise 
answer or I am not recognizing it when I see it.

How important is it to fit the I.D. of snap-on RFI suppression 
ferrites to the size of the wire or cable they are used on? At what 
point does the core I.D. being larger than the wire begin to reduce 
its effectiveness? Surely this must happen at some point? Larger 
cores tend to have higher equivalent series resistance than smaller 
ones, but I wonder how much of that may be given up if the wire 
diameter is much smaller than the core I.D.

I ask because I need to purchase a significant number of these in an 
effort to minimize RFI at 144 MHz. Obviously there is a significant 
price break when buying large quantity of a given part, but I have 
cables of differing diameters to deal with.


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