On Tue, 14 Oct 2003 18:36:01 -0700 paule@sfu.ca writes:
> A friend of mine has a pair of KLM 5el 20meter monobanders which
> are resonant around 14,300 with an SWR over 2 to 1 in the CW portion
> of the band. I was told that the beams were assembled according to
> the provided dimensions, and both beams react the same. The beams
> were initially tried with the homebrew balun from the literature,
> but even when those were replaced with the KLM commercial baluns
> the problem persisted/persists.
>
> Has anyone else encountered this? Would appreciate any suggestions.
>
> Since the beams are already installed on an 110ft tower, I would like
> to find the simplist method of fixing this without (hopefully) having
> to take them down completely.
>
> Thanks in advance.
I only know about the tribanders first-hand, but I think KLM
used a similar dual-driven-element setup on their monobanders.
The rear driven element is the one that predominantly affects
swr on cw. It is connected to the front driven element, where
the feedpoint is, by phasing straps that have been problematic
in the past. The
straps can touch each other, can touch the boom, and can
develop high resistance connections where they fit over the
attaching screws. Maybe someone could take a long fiberglass tube
up there and poke the phasing straps, while someone else is
observing swr from down below, to see if it fluctuates. Also, maybe
you can see a problem through binoculars.
Dave Hachadorian, K6LL
Yuma, AZ
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