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[TowerTalk] New Larger Fair-Rite #31 Toroid

To: <towertalk@contesting.com>
Subject: [TowerTalk] New Larger Fair-Rite #31 Toroid
From: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 28 Mar 2017 09:00:19 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Date: Sun, 26 Mar 2017 16:22:58 -0700
From: Jim Brown <jim@audiosystemsgroup.com>
To: Rfi List <rfi@contesting.com>, towertalk reflector
<towertalk@contesting.com>
Subject: [TowerTalk] New Larger Fair-Rite #31 Toroid

KY8D asked me about a new, larger #31 toroid that has recently been 
added to the catalog. It's 4-in o.d., 3-in i.d, and 1-inch long.

http://www.fair-rite.com/product/round-cable-emi-suppression-cores-2631814002/

Note the impedance data for 1, 3, and 5 turns at the bottom of the page.

Gan's email arrived today (Sunday) so I haven't had the opportunity yet 
to investigate pricing. My guess is at least double the cost of the 
2.4-in toroid, but because it's twice the length (1-in as opposed to 
0.5-in for the 2.4-in toroid), a single core will likely be equivalent 
to two of the 2.4-in cores, so fewer cores will be required to achieve 
the same choking Z. More important, the much larger i.d. will allow more 
turns and/or larger coax.

73, Jim K9YC

##  I saw the  new  4 inch OD  x 3 inch ID  x 1 inch long  type 31 torroid on 
their
site over a year ago, I believe its been there for quite some time.  If you 
look at the
impedance data  for 1,3,5 turns, at various freqs, you will see that the new 
bigger torroid
has just a hair higher results  when you rapidly toggle  between the 2 x cores. 
 Unless  you are
hell bent trying to stuff more than 7 turns of  RG-393  or RG-213 through a 
torroid, IMO, the
bigger 4 inch OD torroid really buys you nothing..and its twice the length to 
boot. Its also 2.5
x  heavier.  420g  vs  117g.

##  Danny,  E73M, and myself looked at the new  4 inch OD torroid, and 
discarded it soon after.
The ID is simply too big, being a whopping 3 inch ID, so even though its twice 
the length of the
smaller  2.4 inch OD x 1.4 inch ID, it buys you nothing when you measure both 
of the torroids,
with 1-7 turns of  393 or 213 .    The smaller torrid is only half the length, 
and works 99% as good.
If you say had a requirement for  6 x 2.4 inch cores... = 3 inches long..... 
you would require 5 x 4.0
inch cores to do the same thing.....  =  5 inches long. 

##  The bigger 4 inch core would be ideal if trying to wind flexible power 
cable around it..or something
like LMR-600UF etc. 

Jim  VE7RF   




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