[TowerTalk] New Larger Fair-Rite #31 Toroid

[Charles Gallo]

Been using a few for a couple of years. In my case, I used them on an air conditioner that has a molded on GFI plug that can't be removed, so it fits through the middle

--  
73 de KG2V
Charlie

> On Mar 28, 2017, at 12:00 PM, Jim Thomson <jim.thom at telus.net> wrote:
> 
> Date: Sun, 26 Mar 2017 16:22:58 -0700
> From: Jim Brown <jim at audiosystemsgroup.com>
> To: Rfi List <rfi at contesting.com>, towertalk reflector
> <towertalk at 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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