[RFI] Snap-on Ferrites

[MICHAEL ST ANGELO]

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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