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Re: [TowerTalk] Quarter Wave Sloper (half sloper)

To: navydude1962@yahoo.com
Subject: Re: [TowerTalk] Quarter Wave Sloper (half sloper)
From: Richards <jruing@ameritech.net>
Date: Sun, 28 Dec 2008 08:00:21 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Greetings Ed --  Please forgive me, as I did not mount my example of 
that antenna on a tower, as you plan to do.  Nevertheless, my experience 
might be helpful as you decide whether or not to try that antenna.

I never got much play out of it at my QTH.   I can say I never got much 
play out of it at my QTH.   I can say, however, that a technician at 
TenTec tole me he used one with acceptable results on his tower, but 
complained about its having an extremely narrow usable bandwidth..   I 
mounted my DX-B antenna on a large metal mast, and used ground radials 
as a return path, at the suggestion of Alpha-Delta's chief engineer. 
I am convinced you really need the tower and yagi beam antenna (which 
serves as a capacity hat)  to get good results with it.   It is a very 
short antenna, only 60+ feet long, so it will be a compromise on any 
frequency you use it on.

I do not think it is entirely correct to say the tower radiates, instead 
of the antenna element, as you suggest.  Instead, the antenna elements 
radiate, and the tower serves as a ground plane/return path, in the same 
way that ground plane made of radials laid on the ground would.

Also, I think the hang angle is more important than you might think.  I 
played with mine at different angles, which caused significant 
differences in the usable bandwidth and caused widely divergent SWR 
readings on my antenna analyzer.  I think you want to mount it quite 
high and have it fairly close to vertical... whatever they recommend in 
the instructions - do it.

Overall, it played lousy on 40 m, and worse on 80 and 160 m, and on the 
lowest bands, had an extremely narrow usable bandwidth.  SWR varied 
between 2:1 and 25:1 within the SSB/phone portion of the band alone. 
It played okay at 3.850  (2:1 SWR) , but not at  3.920 MHz  (>9:1 SWR) 
and was unusable at 3.980 MHz v(20:1 SWR).    I make contacts on it, but 
I was always the weak signal and often could not work stations I could 
hear.

Surely you will get better results at your QTH mounting it to a 
substantial tower, but I would consider something else as it is so short 
on 80 and 160 that I fear you will have difficulty tuning it, and it 
will have such a narrow bandwidth that you will be unhappy with it. 
Based on this experience, I would try some sort of inverted V. dipole 
before I returned to the DX-B.

Anyway, I will again, I acknowledge my comments are based on my 
experience in my more limiting circumstances, but I hope they will 
provide some useful information together with what other information you 
receive.

Just My take...

Happy trails and 73.    ----  Richards - K8JHR ----
=============================================

Edward Sylvester wrote:
> Been trying to get up to speed on these...Learned that height is not 
> important, as it's the tower that will radiate, primarily.  My tower is 70' 
> with a Steppir 3 ele and other assorted antennas for VHF, all on a 10' mast.  
> Looking at the Alpha Delta DX-B, which would give me 30/40/80/160m.  Has 
> anybody installed one of these on a 70' tower?  If so, what height was ideal? 
>  Would like to do this right the first time....Thanks.
> 
> Ed NI6S
> 
> 
>       
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