Topband: Capacity Hat Wire Size
vk3hj_luke at barefoothorse.com.au
Wed Jan 3 01:00:13 EST 2018
In my station for the past several years I have run a top loaded vertical of
similar dimension to what you propose.
A Spider pole is something I would only use in a portable application, not a
permanent home station antenna.
My antenna uses telescopic aluminium tubing tapering from about 65 mm to 25
mm and is around 19 m in length. I originally used six top loading wires of
around 6 m each of Flexweave wire. This turned out to be too heavy and
unwieldy and made the antenna unstable, especially when erecting it. I
changed the top hat to three wires of about 9 m each using medium duty
hookup wire (14x0.32, 1.13 sq mm). Now what I did, I think is rather
ingenious if I may say so, in that I used 4 mm poly rope to guy the top (and
three levels below) and wove the top loading wire into the top guy rope, so
that the rope did the supporting as a guy, and also carried the top loading
wire. This has the advantage of holding up the top loading wires, which are
terminated in a lug onto a small stainless bolt at the top of the aluminium,
and also does not seem to attract the cockies with their bolt-cutter beaks.
The wire is light, and does not cause excessive sag. I secure the top guys
out about 20 m from the centre.
This has survived some decent storms, and bird attack.
Current at the top of the antenna should not be an issue. The main concerns
would be mechanical.
When I have used a Spider pole on DXpedition, medium duty hookup wire as
described above seems ok, even to the feed point, but I've only used a low
duty cycle mode like CW.
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