Towertalk
[Top] [All Lists]

Re: [TowerTalk] Ferrites 31 vs. 77 material

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Ferrites 31 vs. 77 material
From: David Gilbert <xdavid@cis-broadband.com>
Date: Sun, 27 Oct 2019 13:31:47 -0700
List-post: <mailto:towertalk@contesting.com>

I'm sure K9YC, who knows at least 20 dB more on the subject that I do, will have a more thorough explanation but basically the reason is that Type 31 material has desirable loss at HF frequencies instead of only contributing inductance.  When relying only on inductance for common mode chokes you can get undesirable resonances that actually subvert the purpose of using them, whereas the loss in the Type 31 material gives you the low Q performance you want and it does so across a wide frequency range.

73,
Dave   AB7E


On 10/27/2019 11:37 AM, Bob Shohet, KQ2M wrote:
Back ~ 2000, I was using 77 material vs. 43 material for Ferrite chokes and I 
constructed an impedance table by freq.to determined how many beads I should use on 
each band.  Now we talk about and use 31 material instead.  What I don’t recall 
is what happened to the 77 material and why 31 material has seemingly supplanted it.

I would appreciate any thoughts/comments/comparisons on this.

Tnx &73


Bob KQ2M
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
<Prev in Thread] Current Thread [Next in Thread>