J.P. Kleinhaus wrote:
>
> Hi Jeff:
>
> It sounds to me like you're looking for the boom to element mounting
> system that KLM uses.
>
> In my opinion, this might be the worst thing you could possibly
> use for an antenna that needs to stay up longer than a year.
> I have owned various KLM antennas with this mounting system
> and have always needed to keep those things "in stock," as they
> break regularly. The black material is LEXAN (tm) and is quite
> brittle. If you overtighten the assembly the smallest bit, it will
> crack underneath, where you can't see it. One good gust of wind, and
> the element is now twisting in the breeze. Also, I don't think that
> LEXAN is too UV stable, and it tends to deteriorate in the weather.
>
> The easiest way to hang elements is with small plates and four u-bolts.
> Not the best, but the easiest. For a more elegant approach, try to
> replicate the Force-12 approach, with a piece of aluminum bent
> around the boom and riveted in place. The use two (or more) small
> u-bolts to hang the element from there. You can insulate the elements
> from the boom by encasing them in PVC where they go through the
> u-bolts. A picture would be worth at least as many words as the
> preceding paragraph, so you might look on the Force-12 web site.
> I don't have the URL handy, but any search engine will turn it up.
>
> 73, J.P. W2XX
> --
> ======================================================================
> J.P. Kleinhaus, W2XX (fdba AA2DU)
> E-mail: w2xx@cloud9.net
>
> As we say in the software business: "You are hosed."
> ======================================================================
I have always been of the understanding PVC has little resistance to UV,
so will your suggestion as an insulator have much service life?
I have not had experience with Force 12s, but do have the need to
overhaul a KLM 4el40 which is now missing one of the reflector halves.
It came off during a windstorm and probably looked pretty spectacular
during its descent - like a giant spear from the heavens, given that it
is 30 or so feet long with the usual KLM adjunct pieces which make it
look like an arrow head.
Anyway, the missing half of the reflector is on the ground now in one
piece, less the plastic boom to element block. I have new plastic blocks
ready to go, but kindly describe a better system in greater detail, and
I'll be happy to see about getting it attached. We may not be so lucky
the next time it falls off, since it's in a populated area.
Regards,
Madison
w5mj
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