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Re: [RTTY] More on Cushcraft balun

To: "'Bill Turner'" <dezrat@copper.net>, <towertalk@contesting.com>,<rtty@contesting.com>
Subject: Re: [RTTY] More on Cushcraft balun
From: "Joe Subich, W4TV" <w4tv@subich.com>
Date: Mon, 30 Apr 2007 16:55:57 -0400
List-post: <mailto:rtty@contesting.com>
Bill writes: 

> A few weeks ago I posed a question about the power handling capability
> of the balun supplied with the Cushcraft X7 triband yagi, since it
> appeared rather small in size but was rated at full legal power.
> Having burned up a Hy-Gain BN-86 balun a few years ago running 1500
> watts RTTY during a contest, I was trying to avoid a repeat with the
> darn thing 80 feet in the air. :-)

The only concern I would have is if you are shunt feeding the tower 
with that antenna.  All elements on the X7 appear to be insulated.
This makes the only connection to any elements through the balun via 
the shield of the "triband" feedline.  I've seen reports of the 
Cushcraft balun failing under those conditions (perhaps at VE6WZ - 
I can't find it any more).  

If you shunt feed the tower, it may be wise to ground the center 
of the reflector and director (elements 1 and 7) simply to provide 
enough of a top hat that current is not forced through the balun 
to the log cell.  

73, 

   ... Joe, W4TV 
 

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