---- Original Message -----
From: "Bruce Sawyer" <zf2nt@candw.ky>
> anybody knows anything about the alloy used in the
construction of this
> antenna and can determine why/how this break occurred from
that picture, I
> would very much appreciate hearing about it. While I
could splice this top
> section back onto the antenna fairly easily, I don't see
any reason why a
> similar failure wouldn't happen in another 12 days. Given
the cost of this
> antenna and the effort that went into installing it, that
doesn't leave me a
> very happy camper.
Bruce,
Even if the diameter is uniform, very little current flows
in those last ten or twenty percent of antenna length. If
the diameter tapers significantly, the current taper is much
worse. We have the mechanical grief of having thin tubing
waving in the air and that thin small tubing does virtually
nothing to enhance performance. With a good radial system,
there would be very little if not immeasurable difference
using a high Q coil to base load that antenna and eliminate
the top 30-40% or using the full Monty.
If you can't solve the breaking problem and are worried
about base impedance, maybe you can guy the mast and use
wire for the last 20 ft of guyline (or something) and
attach it to the vertical top. That would increase base
impedance and reduce loss if you use a less than ideal
ground system.
73 Tom
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