[RFI] Snap-on Ferrites

[D C _Mac_ Macdonald]

It has long been my belief that it is virtually impossible to keep water OUT of places where you don't want it to go.


Better to arrange for an easy exit for the water that WILL go where you don't want it to go!


* * * * * * * * * * *
* 73 - Mac, K2GKK/5 *
* (Since 30 Nov 53) *
* Oklahoma City, OK *
* USAF, Ret'd 61-81 *
** FAA, Ret'd 94-10 *
* * * * * * * * * * *





________________________________
From: RFI <rfi-bounces at contesting.com> on behalf of MICHAEL ST ANGELO <mstangelo at comcast.net>
Sent: Monday, June 19, 2017 08:47
To: Charles Coldwell; N2TK, Tony
Cc: RFI RFI
Subject: Re: [RFI] Snap-on Ferrites

Tony,

I assume water got into the pores or onto the surface of the cores and cracked when the water froze.

I always enclose my cores, as well as my connectors and protective devices (transzorbs), in an enclosure such as a NEMA box. I run my connections into the box from the bottom or from the side with the cable facing downwards so that water does not run into the enclosure. I cover the side cables with electricians putty to further keep out water. I have put sccreening over the went holes on the bottom to keep out insects.

Mike N2MS




> On June 19, 2017 at 8:03 AM "N2TK, Tony" <tony.kaz at verizon.net> wrote:
>
>
> The cores that came apart were not snap-ons. They were solid cores.
> N2TK, Tony
>
> -----Original Message-----
> From: Charles Coldwell [mailto:coldwell at gmail.com]
> Sent: Monday, June 19, 2017 7:44 AM
> To: N2TK, Tony <tony.kaz at verizon.net>
> Cc: RFI RFI <rfi at contesting.com>
> 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 <tony.kaz at verizon.net> 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:rfi-bounces at contesting.com] On Behalf Of Ed K0iL
> > Sent: Sunday, June 18, 2017 11:20 PM
> > To: john at kk9a.com; rfi at contesting.com
> > 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:rfi-bounces at contesting.com] On Behalf Of
> > john at kk9a.com
> > Sent: Sunday, June 18, 2017 9:44 PM
> > To: towertalk at contesting.com; rfi at contesting.com
> > 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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