Date: Tue, 11 Apr 2017 17:29:22 -0400
From: "john@kk9a.com" <john@kk9a.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Dacron rope
The water is conductive, probably the rope is not that conductive. I
always use Phillystran on elements and insulators at the end of dipoles
where it connects to rope. My 40m OptiBeam uses rope for an element truss
but it has a plastic insulator where it attaches to the element. If your
rope was attached near the tip of the element and you were running a KW it
would likely be destroyed.
John KK9A
## Most 40 + 80 els that are trussed, will only be attached part way out the
ele.
But still, if the dacron is soaking wet, it could conduct just enough so the
ele now
thinks it has a high resistance leg, hanging off to one side...sorta like
adding one half
of a high resistance T bar capacity hat, which will of course electrically
lengthen
the ele, and de tune it to a lower freq. So if an insulator is installed, it
should
be at the dacron to ele interface..and not at the other end of the dacron, at
the
ele to boom riser.
## The dacron is a lot stronger than the typ insulators. On those plastic
insulators, the ones that are aprx 5-7 inches long, with the serrations to
increase
V stand off, they typ come with steel inserts in each hole. I have had to
drill those out
on most of them, so I could use stuff like 8ga RW-90. I could see also having
to
drill them out for darcon rope, depending on size used. They are typ just
500 lb
rated, which is way less than .1875 or .3125 dacron.
## perhaps solid fiberglass rod, like what is sold by max gain systems, might
be the
ticket. They have it up to 1.5 inch solid. Then u could make your own
insulators, any
length, and any hole size on each end. You could also cut some serrations into
it, if you wanted
increased V stand off. I have tried using a single uhmw disc, aprx 2 inch OD,
with a 1 inch ID hole,
which slid over a solid 1 inch fiberglass insulator, then rtv into place.
That alone will increase V
stand off through the roof. Problem was, the uhmw I used was white, and .125
thick.... turned
brittle after 2 years in the sun...junk. Grey PVC or abs would do the trick.
## dunno what the tensile... aka stretch strength is with the mgs solid
fiberglass rods ? I think as
long as the rod was big enough diam..and holes away from the extreme ends, it
will suffice. Last thing
anybody wants is a busted insulator on a 40m yagi...after a heavy wet snow or
ice load.
Jim VE7RF
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