[TowerTalk] Dacron rope

[Roger (K8RI) on TT]

Why not use the small, ceramic egg insulators?  They are quite strong.  
I do use phillystran though.

73, Roger (K8RI)


On 4/12/2017 2:07 AM, Jim Thomson wrote:
> Date: Tue, 11 Apr 2017 17:29:22 -0400
> From: "john at kk9a.com" <john at kk9a.com>
> To: towertalk at 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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-- 

73

Roger (K8RI)


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