[RFI] Snap-on Ferrites

[Roger (K8RI)]

 From my experience, I've had about 15 2.4" toroids hanging at the 
antennas, unprotected for about 5 to 10 years with out a chip.  I either 
super glue, or epoxy the cores together.  An example: 
http://www.rogerhalstead.com/ham_files/AntennaFeed2.htm

73, Roger (K8RI)

On 6/19/2017 Monday 8:03 AM, N2TK, Tony 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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