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Re: [RFI] Snap-on Ferrites

To: "'Charles Coldwell'" <[email protected]>
Subject: Re: [RFI] Snap-on Ferrites
From: "N2TK, Tony" <[email protected]>
Date: Mon, 19 Jun 2017 08:03:37 -0400
List-post: <mailto:[email protected]>
The cores that came apart were not snap-ons. They were solid cores.
N2TK, Tony

-----Original Message-----
From: Charles Coldwell [mailto:[email protected]] 
Sent: Monday, June 19, 2017 7:44 AM
To: N2TK, Tony <[email protected]>
Cc: RFI RFI <[email protected]>
Subject: Re: [RFI] Snap-on Ferrites

Could this have something to do with the unavoidable gap in the 
high-permeability material in a snap-on ferrite?  The majority of the MMF is 
usually in the air gap.

On Mon, Jun 19, 2017 at 6:47 AM, N2TK, Tony <[email protected]> wrote:
> Here in upstate NY I have Fair-Rite FT-240 #31 cores on my RG6 receive 
> antennas - 8 turns. This spring when I did an inspection I saw that 
> several cores had split or had chunks out of them. Do the cores need 
> to be protected from the weather? I replaced the broken cores with the 
> biggest clamp-on, #0431177081, #31 ferrite with 8 turns. They are just lying 
> on the ground.
> Should I enclose them?
>
> I made up four 3/4 wave length RG6 lines for my 80M 4-square. I used 
> the same biggest clamp-on ferrite with 8 turns at the feedpoint. 
> Should I do anything additional such as tie wrap them and/or enclose the 
> ferrite?
>
> 73,
> N2TK, Tony
>
> -----Original Message-----
> From: RFI [mailto:[email protected]] On Behalf Of Ed K0iL
> Sent: Sunday, June 18, 2017 11:20 PM
> To: [email protected]; [email protected]
> Subject: Re: [RFI] Snap-on Ferrites
>
> John,
>
> Seems we can always get more turns around a toroid ferrite (several) 
> than you can on a snap on ferrite (maybe one).  This would make 
> snap-ons less effective than a toroid core based on number of turns.
>
> 73, de ed -K0iL
>
> -----Original Message-----
> From: RFI [mailto:[email protected]] On Behalf Of 
> [email protected]
> Sent: Sunday, June 18, 2017 9:44 PM
> To: [email protected]; [email protected]
> Subject: [RFI] Snap-on Ferrites
>
> I was reading the recent QST article RF Mayhem by WB8IMY. The author 
> said to avoid using snap-on ferrites for problems caused by HF signals 
> as they rarely work well at HF. It is best to stick with circular cores.
>
> Is this correct?  I was not aware that snap-ons were less effective.
>
> John KK9A
>
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--
Charles M. Coldwell, W1CMC
Belmont, Massachusetts, New England
"Turn on, log in, tune out"

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