...snip...
>
> What are the practical issues with helical winding of a vertical with
> rain and/or snow relative to SWR?
...snip...
> Im thinking of a top loaded antenna - 60 ft vert, a 2 or 3 top wires.
>
> 73
>
> Pete W2PM
Pete,
I have experimented with the fiberglass poles you mention. More than likely
not the same but similar mil-spec canopy poles.
Fiberglass is an interesting material. The poles are quite thin, and have a
coupler to give them a profile similar to a swaged pole if made from aluminum.
They are designed to hold up the perimeter of a canvas tent (2 sections). The
6" - 8" connector that couples the poles is far too small to be useful. I have
heard it said that a good engineering approximation for the size of any
connector on any length (fiberglass or otherwise) is about 10% of the length.
A 48" length suggests 5" overlap (e.g. a 10" piece). Although these connectors
are approximately that length, they are completely inadequate for supporting
ANY weight. The connector does not fail, the tube will most certainly fail.
Although you propose simply using it as a vertical with no (or little) weight
on the pole, you forget the weight of the guys. The tighter you pull the guys,
the more "weight" on the mast. I would plan to guy every 3 sections. 60' (as
you suggest) is 15 sections of 4'. That's 5 levels of guys! At 120 degrees
(three directions) and only 10# of pull on each one, you are looking at roughly
75# of tension weight (to which you need to add the sag weight of all that
rope) with the maximum load being on the top guy. Even with 3 or 4 helpers
with 5 arms each, you will never get it to 60'. If you do, the dainty couplers
will most certainly shred the tubing at the very first incidence of flexing.
I even tried using band clamps to reinforce each glass section coupler and the
force was sufficient to not only shred the fiberglass, but it would snap the
band clamps too!
Save your money before you hurt yourself. 32'? Yes, with care, and patience,
and assistance. But 60'? I don't think so! Even if you could get it that
high, the first hint of a wind would render your acrobatic artwork a tangled
nest of scrap.
Ford-N0FP
ford@cmgate.com
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