I agree with KK9A. I think the Philly will outlast EHS if installed and
treated properly. At least I plan so in re-using about 1200 ft
recovered with a 140' R65 AM radio tower I'll be erecting in a three
weeks. The tower needed to be regalvanized as it was just starting to
show surface rust. The Philly looks perfect. Since this was pre 1995
or so parallel strand Philly, I used Spelter sockets and epoxy to
terminate the ends (see my article in Nov/Dec 2014 NCJ about this).
Cable clamps will not work reliably on any Philly and current guy grips
also won't work on the old Philly. I suspect the galvanizing on the new
guy grips are the life limiting factor. A test section of my "old"
Philly with Spelter terminations was tensioned to destruction on a test
stand and failed right at original spec - 26,000 lbs.
Abrasion and water inside that freezes are the enemies of the PE cover.
The Kevlar doesn't have great fatigue life but is probably better than
EHS, so torque bars are likely a good idea on all towers that rotate or
have large antennas. It also has poor abrasion resistance, so a branch
that rubs thru the PE rapidly abrades the Kevlar.
EHS is often recommended as a bottom section as wild fire and vandalism
protection. However, any fire will anneal the heat treating of the EHS
and it should be replaced. Since the Spelter sockets are not field
adjustable, I use a short EHS bottom section so the guys can be "cut to
length" when the tower is erected.
Grant KZ1W
On 5/3/2015 19:00 PM, john@kk9a.com wrote:
I have never done the calculations but I would be surprised if EHS was that
much cheaper than Phillystran after you add in the cost of all of the Big
Grips and insulators. If you also add your time EHS is likely the most
costly option. In my experience the lifespan of Phillystran is more than
EHS, especially in a corrosive environment. Another non-conductive guy
option is Polygon Rod.
John KK9A
To: "<towertalk@contesting.com>" <towertalk@contesting.com>
Subject: [TowerTalk] Rotating tower guying question
From: Andre VanWyk via TowerTalk <towertalk@contesting.com>
Reply-to: Andre VanWyk <kr5dx@yahoo.com>
Date: Sun, 3 May 2015 18:07:48 -0500
I am about to start construction on my new 165ft Rohn 55G rotating tower. My
anchors are 180ft out from the base.
My question is: Just how much is using Phillystrand cable buying me versus
using EHS cable broken up with insulators?
I don't want to cut corners on this installation but the cost on the EHS is
far
lower than Philly and I am sure the lifespan is much longer too.
How about using Philly for 50% out from the tower bearings and then EHS for
the
remaining 50% down towards the anchors?
Any comments / thoughts would be appreciated.
73's
NJ0F
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