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Re: [TowerTalk] 160m 1/4 wave vertical help needed

To: AB5MM <ab5mm@9plus.net>, towertalk@contesting.com
Subject: Re: [TowerTalk] 160m 1/4 wave vertical help needed
From: Larry DiGioia N8KU <towertalk@longwire.com>
Date: Sun, 16 Sep 2007 18:45:30 -0400
List-post: <mailto:towertalk@contesting.com>
Where does your MFJ Antenna Analyzer tell you it IS resonating? Try a 
loading coil, say 8 or 10 turns of 2" diameter, and if things get 
better, that would tell you whether you need the stinger or not.

AB5MM wrote:
> Fellow Top Banders,
>
> I have a matching problem with a Rohn 25G, 160m ¼ wave vertical and am 
> hoping some of you can help me out.
>
> <> The tower is 124'-9" in over all height.  The tower bottom insulator 
> is located at 4'-3" above ground level thus making the vertical radiator 
> a total of 120'-6". All guy wires are insulated from tower as well as 
> being broken up throughout their length. <> 
>
> For now, the ground radial system is made of 22 each, 125' long, 14ga. 
> copper wire.  I plan on installing another 14 radials next weekend.  
> Total number of radials will be 36 at 10 degree spacing.  The soil here 
> in the Sabine River Valley bottomland has a "good rating" of 15mS/m. <> 
>
> My friend (K5ZO) and I have tried every thing we can think of to get 
> this antenna to resonate anywhere in the 1.8 to 2.0 MHz range.  We've 
> tried both low pass and high pass "L" networks, a high pass "T" network, 
> low pass "Pi" network, and a parallel inductor with capacitor, in series 
> with the center conductor. <> 
>
> The best match we were able to achieve was with a 500pF cap in series 
> with center conductor.  This gave us a 1.7/1 swr at 2.113 MHz. (R=64 & 
> X=31) All matching efforts have been made right at the tower feedpoint.
>
>    1. Is the tower too short?
>    2. Do we need to place a capacity hat at the top?
>    3. Would a short stinger out the top (for added height) help?
>    4. What about all the various matching schemes we've tried?  Are we
>       missing something here?
>
> <>Any input or suggestions would be greatly appreciated.  Please feel 
> free to post to the group as I feel this information would be helpful to 
> others as well. <> 
>
> Thanks & 73, <> 
>
> Steve AB5MM
> ab5mm@9plus.net
> _______________________________________________
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>
>
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>   

-- 
Larry  N8KU

 l o n g w i r e . c o m
 HF - DX - CW - Digital

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