[RFI] Ferrite Beads

Jim Brown jim at audiosystemsgroup.com
Fri Oct 22 00:45:04 EDT 2004

On Thu, 21 Oct 2004 22:35:41 -0500, Ford Peterson wrote:

>Ah the rub!  Just exactly what job is it that I need done?  Do I need 30 ohms? 60 ohms?
>300 ohms?  3K ohms?  What measurements do I need to make to determine what is
>needed?  Just exactly what is it that one is supposed to 'study' in the catalog?  Although
>I have not looked yet, the Fair-Rite catalog, to my knowledge, does not have a chart 
>called "Number of split beads needed to suppress a noisy COP on a Toyota V8."  
>Sorry to sound sarcastic here, but the notion of what is adequate for suppression is 
>somewhat illusive to me.  Even a hip shot guess from somebody who has done this 
>before would be great. 1 bead or 10 beads per COP?  

Several people, myself included, who have spent MUCH time studying the behaviour of 
beads have suggested that you do the same, pointed you to the place where you can 
study them, and given you LOTS of detailed guidance. Tom, W8JI, pointed you to an 
applications note he had written, the guy from the car company gave you specific advice. 
Do you want us to engineer your problem for you?  My rate is $150/hr. I don't know what 
others charge. If you do, indeed, study that catalog and the applications notes it contains, 
you will learn a lot, and you might learn enough to solve your problem. Isn't that what this 
list, and ham radio, is all about?


Jim Brown  K9YC

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