[RFI] looking for larger size ferrites

[Cianciolo, Paul, W1VLF]

Jim makes a bunch of good points here.
Take a look at the datasheet for the #31  snap on cores. Look on page 2, where it show the series equivalent loss impedance  for a single pass through the core as a function of frequency.
Impedance is a the square of the turns ratio.  At least for a first order approximation.  Jim's detailed papers can help you greatly beyond that. 

https://www.newark.com/pdfs/datasheets/Fairrite/0431176451.pdf


73,

Paul Cianciolo, W1VLF
ARRL EMC Engineer

ARRL - The national association for Amateur RadioT
225 Main Street, Newington, CT 06111-1400 USA 
Telephone: (860) 594-0392 
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-----Original Message-----
From: RFI <rfi-bounces+pcianciolo=arrl.org at contesting.com> On Behalf Of Jim Brown
Sent: Friday, May 1, 2020 5:10 PM
To: rfi at contesting.com
Subject: Re: [RFI] looking for larger size ferrites

What frequency(ies) are you trying to suppress?  In general, simply clamping a ferrite over coax or hard line is effective only from about
100-500 MHz, depending on the ferrite mix. Fair-Rite #31 or #43 below about 250 MHz, #61 above that. Multiple turns on Fair-Rite #31 are required below that frequency.

http://k9yc.com/2018Cookbook.pdf
http://k9yc.com/ChokesVHF.pdf

I've found Arrow Electronics to be a great vendor for the the quantities of parts that I need IF they have them in stock, and they stock a lot of Fair-Rite. Shipping is free for a $50 order placed online. Other vendors and a tutorial discussion of how ferrite chokes work are in this link.
http://k9yc.com/RFI-Ham.pdf

73, Jim K9YC

  On 5/1/2020 11:56 AM, David Huff wrote:
 > I am looking for a source of larger size ferrites, preferably clamp on style big enough to go over LDF4-50 cable. (16 to 18mm Inside Diameter) _______________________________________________
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