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Re: [TowerTalk] tuning A3s

To: towertalk@contesting.com
Subject: Re: [TowerTalk] tuning A3s
From: jim Jarvis <jimjarvis@optonline.net>
Date: Thu, 19 Mar 2009 15:21:20 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I threw a connector on the end and used the AEA analyzer with the tower
standing up..not cranked up but at 21 ft..and it's still the  
same..low on
all bands... On 20 lowest at 13900(1.63) , on 15M lowest at 20900 
(1.1), and
on 10M lowest at 27600(1.08)...I assume just shorten the dipole a bit?
                                    Tom  N3ZC


Tom,

It is normal for an antenna to appear resonant low, when it's close  
to the earth,
and to have its vswr center rise, as the antenna goes up.    Each  
antenna and site
are a bit different, in that regard.   But in general, I would expect  
to see the vswr centers
move up by 100-200 KHz, in going from 20-60'.

Two approaches:

1)  Crank up the tower to full height and repeat the measurement.
Bring it down and make necessary adjustments.

2)  Shorten the DE a bit, then put the tower to full height,  repeat  
measurements,
and bring it down to fine-tune.

My guess is that your vswr center @ 55' will turn out to be  
14,050-14,100, with no adjustment.
If you're looking for higher in the band, then perhaps try shortening  
a bit, first.

Since they're all low by about the same amount, if you adjust the  
center, you'll bring them all
in.   Once you get 20 where you want it, you MAY have to diddle with  
15 and 10 a bit, although
usually, the factory settings work fine.

Jim/N2EA
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