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Re: [TowerTalk] Vertical dipoles

To: Paul Christensen <w9ac@arrl.net>
Subject: Re: [TowerTalk] Vertical dipoles
From: John Tait <johnei7ba@eircom.net>
Date: Wed, 18 Nov 2009 12:44:01 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

Paul Christensen wrote:
>>  I'd have to disagree with that statement. I have both vertical
>> dipoles and  inverted Vs for 80 and 160m.
>>     
>
> John,
>
> Why are you now feeding your vertical dipole asymmetrically?  I see a 
> center-fed element in one diagram, but it changes to a bottom feed at the 
> end of your web page.  Tnx!
>
> Paul, W9AC 
Hi Paul...
        I originally fed at the centre of the vertical wire, but as I 
said on the web page, I moved the feed point because it's mechanically 
much simpler to feed at the bottom. The feed impedance doesn't change 
dramatically, and there is less coupling to the coax shield from the 
radiation field. Even when fed at the physical centre point of the 
dipole, it is still an asymetric feed, because the dipole is unbalanced 
by having one end so close to ground, and the other end in the clear.
  An _effective_ common mode choke is must.
                     John EI7BA
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