[TowerTalk] [RFI] Snap-on Ferrites

[EZ Rhino]

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 at 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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