From:
Fred Hopengarten, K1VR
Six Willarch Road * Lincoln, MA 01773-5105 * 617/259-0088
e-mail: k1vr@juno.com
Big antennas, high in the sky, are better than small ones, low.
N4SI wrote:
>Water pipe, whatever schedule, is not a structural device; it is
>designed as a transportation medium. You will not find structural
>data (i.e. tensile strength) anywhere for it.
>
>In the folly of my youth, I, too, installed water pipe masts in a
>number of local installations (there wasn't much tower stuff
>available then, and I was the local "expert"). Some were not
>particularly stressed with hardware, but some were.
>
>One bent about 30 degrees and had to be removed with a crane.
>Fortunately, the owner is still a friend of mine. Mine developed a
>slight bend before I replaced it with real mast. I consider myself
>very lucky, as are you.
>
>There are only two kinds of water pipe masts: those that have failed,
>and those that are going to.
>
>Do yourself a favor and start budgeting and designing for replacement
>masts.
>
>73, Rod N4SI
> The DXer formerly known as N9AKE
K1VR opines: Rod's words should be included in the towertalk FAQ (big
hint to K7LXC).
In my youth, I tried to operate the W1AF station. It had a Classic 33
and a Moseley 2 el. "shorty forty" mounted on water pipe. Located in
downtown Cambridge, it was lower than most buildings surrounding it, but
the water pipe still bent. Trying to cut the water pipe to permit
removal was awkward. We couldn't get a hack saw into the Rohn 25, so we
wore gloves and took turns cutting the water pipe with a hack saw blade
held in gloved hands. It must have taken two hours.
There are only two kinds of water pipe masts: Those that have failed and
those that are going to fail.
Having said that, if I found myself on a desert island and had no choice,
I'd put a smaller water pipe inside a bigger one to resist bending. But
I'd keep even that as short as possible.
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