From:
Fred Hopengarten K1VR 781/259-0088
Six Willarch Road
Lincoln, MA 01773-5105
permanent e-mail address: fhopengarten@mba1972.hbs.edu
On Mon, 22 Jun 1998 12:53:07 -0500 Thomas Johnson <K9KJ@qsl.net> writes:
>At this point I will need to guy it. Would you recommend Kevlar
>(Phillystran) or Galv Steel Cable? and what thickness?
K1VR: I use and love Phillystran, but it may not be right for you.
The advantage is that it is non-conductive. This permits you to (1) load
the tower on 80 or 160 -- I load mine on 160, (2) stack Yagi-Uda
antennas without concern as to whether a metallic guy wire may be
resonant on a frequency of interest, and (3) hang wire antennas (or wire
reflectors, directors, verticals, and so forth) without concern about
interaction with the Phillystran guy set.
In your case, you tower is against your house, so you may not want to
load it and use it as a transmitting antenna.
Disadvantages of Phillystran are: (1) additional initial cost, especially
when compared with used insulators or guy wire and (2) the fact that
Phillstran requires protection (try engine hose impregnated with
fiberglass) if it rubs against a tree branch.
I enclose below three other significant Phillystran posts from the past:
At 04:37 PM 3/25/96 -0500, you wrote:
>
>I have some of the older (potted ends) phillystran. I
>havn't called the company yet, but thought I read here that
the ends were not available any more. Is this true? Hard
to believe this stuff is worthless.
>
>Bill, KM9P
Yep, it is worthless! So just box it up and send it out
here and I will dispose of it for you!
The last time I checked the original heads Philadelphia
Resin supplied were no longer available. But it is possible
to use a Spelter Socket (both open and closed are available
from Crosby and from other companies). The socketfast blus
was still available the last time I checked.
The Spelter sockets are more expensive than one would
believe but at least they require less of the potting
compound. Ones for 11,000 pound rated Philly were pushing
$20 each a couple of years ago. Probably somewhat less for
smaller material. There are foreign made ones available at
a small discount.
I have some 3/8 EHS equivalent Philly on my rotating tower.
The guys were made of the original material and were used on
a broadcast tower before I picked them up. They used
Spelter Sockets and they have been in use with my big
antennas for a number of years.
You can get Crosby products through local distribution or
the address I have is in Tulsa, OK. 918-834-4611 (from an
old catalog--hope it is still current)
John Brosnahan W0UN
La Salle Research Corp 24115 WCR 40 La Salle, CO 80645
voice 970-284-6602 fax 970-284-0979 email broz@csn.net
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In a message dated 96-04-19 03:08:44 EDT, you write:
>The last time we visited this subject, three camps arose:
>(1) Why bother breaking up guys? If you put a monetary
>value on your time, buy and install Phillystran to a height
>of 12 feet above ground. If you want to save some money,
>use Philly on the top two sets and go with solid steel
>below.
>(2) Break 'em up. If you keep your eyes open you can find
>good deals on grips, insulators, clips, whatever. Why
>bother valuing time? The construction is part of the
hobby.
I bought my stuff from CATV supplier.
The 1/4 inch EHS was about five cents a foot, 1/4 inch guy
grips were $0.79 each, and insulators were $2.50.
I had $453 in guying a 130 foot tower at four levels with
non-resonant guys (over 70 insulators).
I did a cost analysis, and the EHS steel system was ~$200
cheaper than Phillystran.
Tom W8JI
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Darn it, I said in the orig Summary that the
K4VX article on guying was in August QST,
which is true. I just forgot to say which yaer !!
Its Aug 1993. Sri bout dat. Ed KG4W
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On Wed, 5 May 1993 16:50:34 +0000, "Steve Fraasch"
<Steve_Fraasch@ATK.COM> wrote:
> 1.) Has anyone lost a potting end, snapped a guy, or cut a
guy by accident?
K1VR: I've seen two guys abraded by branches until they
popped. Solution: As you pass by trees, slip 'stran
through some gasoline hose of correct size (i.d. just barely
larger than 'stran o.d.). The gas line (source: any auto
parts store, on rolls and sold by the foot) has wonderful
strength properties because of an interwoven fabric within
it, designed to avoid failure due to abrasion.
> 2.) Can large antennas be put up safely ? If a sharp piece
of hdwe catches the guy, can the guy be cut?
K1VR: Not readily. But a knife and a lot of effort will
cut it.
> 3.) Does weather or ultra-violet limit guy life?
K1VR: Doubt it. 'Stran specified as UV resistant.
> 4.) Do tower vibrations dampen out? [K1VR: Dunno what
you mean.] Does the elasticity of 'stran cause the tower to
sway more than it otherwise would w/ steel guys? [K1VR:
YES.]
> 5.) I assume that one would follow the same guy schedule
given in the Rohn book. Do any mods to those drawings apply
for 'stran? [K1VR: No.]
These remarks do not come from a civil or mechanical
engineer. I'm just a humble lawyer, but I climb my own
towers.
====================
From: "David L. Thompson" <thompson@mindspring.com>
To: <towertalk@contesting.com>
Date: Mon, 18 May 1998
Subject: [TowerTalk] Another source for Kevlar cable
While looking through the Glen Martin Engineering web page I came across
the
fact that they sell Kevlar cable. The Phillystran name is nowhere to be
found. Kevlar is made from an aramid fiber produced by E. I. Dupont.
They sell 2100, 4000, and 6700 lb breaking strength versions that run
quite
a bit higher than Phillystran (I have 1997 prices maybe its gone higher).
HP-2100 60 cents/ft
HP-4000 98 cents/ft
HP-6700 $1.36/ft
no mention of volume pricing.
Unlike Phillystran they recommend heavy duty thimbles, U-bolt cable
clamps
(4 per end) and an end cap to keep the kevlar from unravelling. This is
for
all sizes not just 2100.
Refer to http://www.glenmartin.com/catalog/page18.html for the full info.
No relationship with Glen martin just information I though towertalkers
would want the info.
Dave K4JRB
and
From: K7LXC <K7LXC@aol.com>
To: <towertalk@contesting.com>
Date: 18 May 1998
Subject: Re: [TowerTalk] Another source for Kevlar cable
In a message dated 98-05-18 12:59:54 EDT, thompson@mindspring.com writes:
<< While looking through the Glen Martin Engineering web page I came
across
the
fact that they sell Kevlar cable. The Phillystran name is nowhere to be
found. Kevlar is made from an aramid fiber produced by E. I. Dupont.
They sell 2100, 4000, and 6700 lb breaking strength versions that run
quite
a bit higher than Phillystran (I have 1997 prices maybe its gone
higher).
HP-2100 60 cents/ft
HP-4000 98 cents/ft
HP-6700 $1.36/ft
no mention of volume pricing.
Unlike Phillystran they recommend heavy duty thimbles, U-bolt cable
clamps
(4 per end) and an end cap to keep the kevlar from unravelling. This is
for
all sizes not just 2100. >>
This is Phillystran which is a Kevlar aramid fiber strand product.
The
fact that GME is still recommending cable clamps a couple of years after
the
factory introduced the Preformed grips and told people NOT to use cable
clamps
shows that they're behind the curve in their information.
Steve K7LXC
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