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Re: [TowerTalk] Strange Balun...please help

To: Doug Smith <doug@w7kf.com>
Subject: Re: [TowerTalk] Strange Balun...please help
From: Herbert Schoenbohm <herbert.schoenbohm@gmail.com>
Date: Wed, 25 Jan 2017 14:22:38 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Thanks Doug.....It appears to be military surplus for a T2FD which are common at military and diplomatic installations as well as sent to National Guard com units that have no real use for them.



Herb, KV4FZ


On 1/25/2017 1:02 PM, Doug Smith wrote:
I’d expect those to be flux coupled RF transformers designed for use with terminated 
antennas.  Think rhombic or vee beams or terminated dipoles.  Any chance they’re actually 800 
ohms on the load side?  A four to one turns ratio.  I’ve seen such things in military and 
commercial settings.

Doug, W7KF



On Jan 25, 2017, at 8:25 AM, Herbert Schoenbohm <herbert.schoenbohm@gmail.com> 
wrote:

I came into the possession of two unusual high power baluns, one with 125' of 
RG-213 attached and the other with a two foot lead of coax attached.  They are 
seal and inside PVC with the coax going inside the bottom and large eyelets for 
the wire and support in the center. They appear to be commercially made.  I 
soon found tat they are not current baluns judging from the discovery that 
there is no DC continuity to either wire connection from the coax.  With a 
bridge and a 50 ohm non-inductive resistor the VSWR is very high.  However when 
I put a 1000 ohm resistor on the antenna connections the balun is flat from 1.8 
to past 60 Mhz.  This would make the device a 20:1 balun which is something I 
have never heard of. What kind of antenna requires such a high impedance feed?  
If anyone has any knowledge of the use for these devices please let me know. 
Thanks


Herb, KV4FZ


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