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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