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Re: [TowerTalk] R7000

To: Rudy Severns <n6lf@arrl.net>
Subject: Re: [TowerTalk] R7000
From: Bill Coleman <aa4lr@arrl.net>
Date: Mon, 15 Jun 2009 08:26:36 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On Sep 15, 2008, at 12:16 PM, Rudy Severns wrote:

> Some multiband commercial verticals will work without a ground system.
> During my experiments earlier this year I tried an R7000 first with  
> a large
> ground system and then removed the ground system.  I could barely  
> tell the
> difference.  This check was done on 40m.  Didn't see if this held  
> for the
> higher bands but I suspect it would.
>
> The signal from the R7000 was a couple of dB lower than a full 1/4- 
> wave with
> the same ground system.  I suspect that was mostly due to loading
> inefficiency which is to be expected in short loaded antennas.

I have an R7000 mounted only 8 feet high. A couple of years ago, I  
added eight 12 foot radials from the base of the support mast across  
the ground. I found that this improved the reception of the antenna  
markedly.

This antenna was designed to be mounted about 18 or more feet off the  
ground. I think the radials help by reducing the ground losses that  
occur from it being so close to the ground.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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