At 03:23 PM 9/23/98 -0400, w2xx@cloud9.net wrote:
>
>Ooooppsss.....
>
>I just realized I may have led NO6X astray. I recall from a
>recent thread on Towertalk that mixing Phillstran with EHS at
>different guy levels is a no-no!
>
>You can use EHS and Philly in series, i.e., with a lower portion
>of EHS for anti-vandalism etc., but it might not be smart to
>use them in "parallel," due to the different elasticity and the
>possible effect on tower motion.
I hope that the emphasis is properly on the "might." But maybe I can smoke
out the mechanical engineers with the following question:
I have 100 ft of Rohn 25, currently guyed, per the catalogue, with 3/16
EHS. My upper guys use 21-foot fibreglass power pole insulators to get the
metal away from the yagi, then EHS the rest of the way to the anchors where
they are grounded. The other 2 guy sets are rounded EHS, insulated from
the tower at the tower, grounded at the anchors, and otherwise unbroken.
I'm planning to stack a second tribander below the first, and modeling
suggests that I must get rid of the metallic portion of the top guy. I'm
planning to replace the top guys with Phillystran (transitioning to EHS
near the bottom for the usual reasons) and move my current top guys to the
middle, insulators and all.
My intuition tells me that Phillystran, properly tensioned, should be fine
for the top guys, even though the bottom two sets are much more stretchy.
Seems as if it could be more problematical if you had steel above and
Phillystran in the middle so that the thing could do a hula in the wind.
Am I listening to the wrong little voices?
73, Pete Smith N4ZR
In wild, wonderful, only middlin' rare WEST Virginia
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