[RFI] Ferrite Beads from DX Engineering

[Jim Brown]

On Mon, 11 Jan 2010 15:36:51 -0500, David Jordan wrote:

>Thanks for the info...don't see how I'll be able to wrap spark
>wires...doesn't seem very practical of an application.

Ferrite beads in pulsed circuits (like  spark plug wires) would work 
slightly differently. There, they work by slowing down the rise/fall 
time of the current pulse (or smoothing its corners), which in turn 
reduces the strength of harmonics. It's those harmonics that we hear 
in the ham bands. In that application, I WOULD use a single ferrite 
"clamp-on" on each wire. 

Ferrite chokes on other wiring can help ingnition noise to the 
extent that they prevent the COUPLING of that noise on that wiring. 

73,

Jim Brown K9YC