N4KG comments below:
On Mon, 20 Jul 1998 17:32:30 -0700 "Robert L. Shohet" <kq2m@eci.com>
writes:
>
>snip<
>
>I intend to (ultimately) stack 4 10 meter beams and 3 15 meter beams
>as follows:
>
>10 @ 96'
>15 @ 90'
>10 @ 69'
>15 @ 60'
>10 @ 46'
>15 @ 30'
>10 @ 23'
>
>The Rohn 25 will be guyed @ 30, 60 + 90'. At the various heights, the
>guy wires will come within about 3 feet of an element tip when the
>antenna is turned at a certain angle (the end of the boom will NEVER
>come closer than about 7' from the guy wire). Will this be a problem
>for the SWR and radiation pattern of the antenna?
>
>Would it help to use a SMALL non-resonant lenght of guy wire
>"looking-at" the antenna in the horizontal plane or just use a
>"normal" non-resonant length?
>
>I'd really appreciate everyone's thoughts and comments on these
>questions!
>
>73
>
>Bob KQ2M
>
>kq2m@eci.com
>
Bob,
It is absolutely imperative that you place an insulator as close to the
tower as possible when using metal guy wires. Mine are 3 to 4 ft.
Remember, the tower is conductive so you have metal from insulator
through the tower back to the other first insulators. I like to use
10 to 12 ft between the first and second insulator which should
be almost "invisible" even on 10M. Perhaps even a second 10 to
12 ft piece, then followed by the standard 27, or 40, or 56 ft. as
needed.
A friend once told me he really liked his tribander except on 15M.
It turned out his top set of guys was 10 below the beam, with
insulators 10 ft from the tower. This effectively placed a 21 ft
continuous conductor (10 ft plus 1 ft of tower plus 10 ft of wire)
directly below the driven element which is very close to resonance
on 15M and spaced about 0.18 WL below the driven element.
As most people know, I am a big advocate of a low beam for
the high bands (preferably 35 to 40 ft), but I question the benefit
of your 23 and 30 ft high placements. How about 30 / 60 / 90
on 10M and 36 / 66 / 96 on 15M ?
73, Tom N4KG
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