[TowerTalk] Ferrite- Type 31 Material

[Jim Brown]

On Sat, 18 Dec 2004 09:14:14 -0700, Richard Zalewski wrote:

>I continue to do research on selecting the correct ferrite for HF RFI
>problems.  What I have found so far is that it appears that Type 31
>material is best suited for 1-30 Mhz.  This is not the usual 43 or 77
>material sold by most.  43 and 77 have a wider range but not the
>impedance in the 10mhz range as 31.  Before I go order up a bunch of
>31 material stuff does anyone have any experience using 31 material?

I agree with your assessment.  In general, you will achieve higher R over 
the broadest frequency range in the HF spectrum with #31 than with 43, 
44, 77, or 78. You can "tune" the peak attenuation by varying the number 
of turns. 


Jim Brown  K9YC