[RFI] Sources For RFI Suppression Ferrites

Jim Brown jimbrown.enteract at rcn.com
Mon Nov 3 09:21:31 EST 2003

There is excellent technical data available as a pdf download from
Fair-Rite, one of the major mfrs.  The catalog includes some
information that is almost tutorial in nature, as well as a lot of data
(including R, L, Z plots vs freq) on their products. 

I see a few of the smaller Fair-Rite products (mostly beads to fit over
small wires) listed in places like Allied, Newark, and Digi-Key.  I've
been doing some research on the effectiveness of various ferrites for
cleaning AM BC and HF out of audio systems. I'm not far enough along
with it to have any definitive results, but I'm hoping to come up with
specific recommendations for various frequency ranges. You've got to
buy a lot of pieces to deal directly with these mfrs -- if you aren't
an OEM, forget it.  Once I've gotten this far, I think I can get a
certain mfr of quality audio parts to make a quantity buy of the most
useful parts. 

I would also be interested in the experience of others, as well as any
other good publications on the topic. 

Jim Brown K9YC

On Mon, 3 Nov 2003 08:38:34 -0600, Linden, Mike (BRC-Hes) wrote:

>  Someone asked a while back for information on sources of RFI Suppression
>Ferrites. Here are some places I am aware of:
>Palomar Engineers
>Very large selection of ferrites -- have very helpful Hams on staff. They
>will send you a catalog and RFI tip sheet upon request. I have ordered from
>Palomar and am satisfied with them.
>Ocean State Electronics
>Fair selection of ferrites and better prices. I have ordered from Ocean
>State and am satisfied with them.
>Kits and Parts Dot Com
>Fairly small selection of ferrites, but some great prices on FT114s (5 for
>$5) and FT240s ($5 each)! They only accept mail orders or Pay Pal. I just
>placed an order for a few FT240s, but haven't received it yet.
>Very good article on the use of ferrites for RFI suppression:
>  I've been told that material 43 ferrites are good for general HF RFI
>issues. However, I've also been told that material 77 is best below 5 MHz
>and material 43 is best 7 MHz and up (within the HF spectrum).
>  73, Michael N9BDF
>PS  The "Amateur Radio Emergency Communications Consistency Act" (HR 1417)
>and the "Amateur Radio Spectrum Protection Act" (HR 713 & S. 537) have been
>reintroduced in Congress. Please contact your Congressmen to ask for their
>support of these bills! See the following ARRL link for details:
>RFI mailing list
>RFI at contesting.com

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