[Amps] Ferrite toroids

[Jim Brown]

On 8/26/2011 5:33 AM, Carl wrote:
> Its not 100% but close
> enough since ferrites have a wide production tolerance.

DANGER, WILL ROBINSON!  Ferrite materials have VERY different 
characteristics as a function of frequency.  This simple-minded sort of 
procedure only tells you about the low frequency behavior of the core -- 
that is, well below the self resonance of the core with the conductor 
passing through it.  A much more sophisticated approach is needed to 
understand the characteristics at HF and VHF.

Anyone wanting to characterize a ferrite material would do well to first 
study my tutorial and then the Fair-Rite catalog.  Fair-Rite is 
certainly not the only company making ferrites, but they are by far the 
dominant one in North America, and their catalog provides 100 times the 
information of all the other manufacturers combined.  You can actually 
LEARN a lot from studying their catalog. Virtually all ferrite materials 
commonly sold to hams are made by Fair-Rite.

My tutorial is http://audiosystemsgroup.com/RFI-Ham.pdf

73, Jim Brown K9YC