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[TowerTalk] k9yc, cia, 1966, ferrite coax cable chokes, the secret 5000

To: Tower Talk List <towertalk@contesting.com>
Subject: [TowerTalk] k9yc, cia, 1966, ferrite coax cable chokes, the secret 5000 ohm target
From: Kevin Normoyle <knormoyle@surfnetusa.com>
Date: Sat, 22 May 2010 22:16:18 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I went searching just for fun...

Hey you know it's gotta be good when K9YC is dropping references to CIA 
visits to his lair, when talking about baluns.

I think this is the report in question.

"FERRITE CABLE CHOKES. By Ernest T Harper, ARMY ELECTRONICS COMMAND FORT 
MONMOUTH N J INST FOR EXPLORATORY RESEARCH"
http://books.google.com/books?id=P9BaNwAACAAJ

Apparently the report identified 3 cable chokes for getting >5k ohms 
across the entire 2-30Mhz.
I can't find a copy of it online though, just the summary below. It 
apparently was available publicly when it was published in 1966.

also here:
http://www.dtic.mil/srch/doc?collection=t3&id=AD0631053 
<http://www.dtic.mil/srch/doc?collection=t3&id=AD0631053>

Title    FERRITE CABLE CHOKES.
Authors    Ernest T HARPER, ARMY ELECTRONICS COMMAND FORT MONMOUTH N J 
INST FOR EXPLORATORY RESEARCH.
Publisher    Defense Technical Information Center, 1966
Length    47 pages
AD0631053

Book overview
A theoretical and experimental investigation was made of the factors 
affecting the performance of toroidal inductors with ferrite cores and 
windings of coaxial cable. Design procedures are developed and described 
for toroidal cable chokes which provide a specified minimum amount of rf 
isolation over a band of frequencies. It is shown how one may maximize 
the width of the frequency band for a given rf isolation impedance. The 
entire band, from 2 to 30 Mc, may be covered by a set of only three 
individual cable chokes, providing an rf isolation of better than 5,000 
ohms.

1966 - 47 pages

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