[TowerTalk] phillystran vs lightning

[Pete Smith]

At 02:29 PM 2/13/00 -0500, w8zh@juno.com wrote:
>
>
>the guys on our 150ft tower are not broken with insulators. as part of
>the stacked tribander project we are planning to break the guys with
>insulators or replace the top 40 ft of each guy with phillystran. our
>tower is probably struck by lightning , due to our hilltop location, 3 or
>4 times a year.. the tower has an 8ft rod on each leg  connected with 2/0
>copper and a rod on each guy anchor as shown in the rohn catalogs. i
>guess my question is has anyone heard of damage to phillystran after a
>lightning strike.. i spoke with them last week and they were noncommital
>at best. i am kind of leaning toward the insulators, which will just
>flash over.  the phillystran would get  all of the metal out of the way
>of the antennas. 

The trouble is that the grounded portion of the upper guys will still be
inside the aperture of the lower tribanders in the stack.  I use 21-foot
fiberglass power pole insulators for the top section of my top guys, to get
them clear of the tribander at the top, but in modeling a second tribander
below it on a sidemount, it has become apparent that I need to replace the
upper guys with something nonconductive for a MUCH longer distance from the
tower.  I don't think 40 feet will begin to do it.

For a project of that size, you might want to consider Polygon pultruded
fiberglass rod guys -- significantly cheaper than Phillystran and a lot
stronger, if you can swing the medium purchase requirement and your
shipping problem is manageable (like go pick it up)...

73, Pete Smith N4ZR
n4zr@contesting.com 

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http://206.102.70.3/search.htm

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