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Re: Topband: 75ohm coaxial snake beverage?

To: "Jerry Keller" <k3bz@arrl.net>, <topband@contesting.com>
Subject: Re: Topband: 75ohm coaxial snake beverage?
From: Roy Morgan <roy.morgan@nist.gov>
Date: Tue, 25 Jul 2006 09:55:55 -0400
List-post: <mailto:topband@contesting.com>
At 09:21 AM 7/25/2006, Jerry Keller wrote:
>What beads exactly (source, item #, etc) would be good for this use on RG6 ?

Jerry,

I don't remember that he gives details, and don't have the book at 
hand.  One diagram does mention "Wireman" beads.  At:
http://thewireman.com/index.shtml
I find his item 913,  FB-43-2401 Ferrite Bead u = 850 at .25 each in 50 
quantity.
  http://thewireman.com/baluns.html#901
Also available in the type 73 material u - 2500.

I do remember that 50 beads are indicated in at least one place, maybe two 
or more places.  Also, he says some thing like: "Of course, use of ferrite 
beads with lager coax such as RG-8 or RG-11 is not practical." I presume he 
means it's not practical because of the cost of 50 or a hundred beads.

He does give the needed RF impedance of the de-coupling unit (on the order 
of 1000 ohms or so) and the associated inductance needed for 160 
meters.  He also mentions the length of coax needed  ( a lot ) to make such 
a de-coupling inductance for 160M by winding the coax up into a coil.

Roy



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