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Re: [TowerTalk] [RFI] Snap-on Ferrites

Subject: Re: [TowerTalk] [RFI] Snap-on Ferrites
From: Chris <EZRhino@fastmovers.biz>
Date: Mon, 19 Jun 2017 08:11:16 -0600
List-post: <mailto:towertalk@contesting.com>

> Chris:
> 
> Clarify: When your talking about turn in a snap 0n your referring to the 
> large snap, 1.75 X 2.25 with a .75 opening, not the 1.255 X .75 with a .312 
> (5/16_ opening..?

A turn = winding the wire/cable through and around the core, has nothing to do 
with size.
> 
> So inquiring minds wonder when you buy a printer/TV set, etc and there is a 
> molded Ferrite block on the AC line. what are they trying to block..??

Ask the manufacturer.  I have no idea what mix they are using or what their 
target choking frequency is.  But I doubt they are thinking of hams and trying 
to block HF!
> 
> So when the Ham says .."Hey I got rid of my RFI on my TX signal by clipping 
> on three blocks of ferrite..."

Too vague....
> 
> And what about the Ham at the show that was selling  ferrite snap ons (small) 
> with a blue and red labels with bold arrows printed on the black label? What 
> coulkd the arrow mean??

No idea what or who you are referring to, can't comment.  If there is no 
manufacturer listed with the mix, it is impossible to tell what you've got.

> 
> Thanks,
> 
> 
> -Bill .. KC4PE
> 
> 
> On 6/18/2017 11:11 PM, EZ Rhino wrote:
>> I think what he (the author) means is this:
>> 
>>  A snap-on, without multiple turns through around it, isn't effective at HF 
>> frequencies.  We're talking about mix 31 or 43 here.  If you wind multiple 
>> turns around the snap-on (assuming you pick a size large enough to do so for 
>> the cable you're trying to choke) then the choking frequency goes down (to 
>> HF range) and the impedance goes up, which is what you want.  So it's not 
>> the snap-on that is the problem, it is how you are using it.  If there was 
>> such a thing as mix 73 snap-on that was large enough, then that would work 
>> as a string of beads choke (because it is effective at HF).  But it would 
>> take a lot of them, say 50, to get the proper amount of choking impedance.  
>> A single snap-on just don't have enough umph.
>> 
>> Hopefully I worded this technically correct.
>> 
>> Chris
>> KF7P
>> 
>> 
>> On Jun 18, 2017, at 20:44 , <john@kk9a.com> wrote:
>> 
>> 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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>> 
>> 
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