Topband: Ends for older Phillystran

[Grant Saviers]

Thanks to all who provided info and suggestions.

It appears that a practical solution to be able to use "old" Phillystran 
might be to use wire rope saddle clamps at the right quantity and 
tightening torque.  So, based on  posts, I am experimenting with 4 
clamps with nut tightening torques (5/8" clamps for the nominal 5/8" 
diameter PS I have 1800' of) at values of 25, 40, 55, and perhaps 70 
ft-lbs (95 ft-lbs are recommended for 5/8" diameter wire rope).

I've talked with West Coast Wire Rope and Rigging here in Seattle, they 
have a 5k to 500k lb pull stand for up to 180' long cables that costs 
$150 per hour.  However, this test cost would be prohibitive to test for 
creep, so I've (reversibly) modified my H frame arbor press to be able 
to do tensile testing up to about 20,000 lbs.  This way I can test the 
sample configuration under tension for days.

So I am now testing  a 4' double ended section of old PS with 4 clips 
each end to determine what loads and what torque values cause what 
behavior.  I've also done a limited literature search about Kevlar fiber 
properties, and have not discovered any "show stoppers" for a saddle 
clamp termination.

So far a test configuration has been adequately stable at 5000# 
continuous load for 10 days.  I will post more detailed results of the 
testing after I am further along with the tests.

Grant KZ1W


On 1/13/2014 6:00 PM, Lloyd Berg - N9LB wrote:
> Sorry, I meant to send this follow-up to the entire reflector.
>
> The newer version Philly-strand is excellent - it has become the standard
> for guying insulated AM broadcast towers, and is also used on some FM & TV
> broadcast towers when guy lines have to pass thru the aperture of side-mount
> VHF and UHF antennas.
>
> 73
>
> Lloyd - N9LB
>
> -----Original Message-----
> From: Lloyd Berg - N9LB [mailto:lloydberg at charter.net]
> Sent: Monday, January 13, 2014 5:15 PM
> To: Grant Saviers;topband at contesting.com
> Subject: RE: Topband: Ends for older Phillystran
>
>
> Hi Grant!
>
> I worked at WDAE Radio in Tampa, FL back in the 80's and 90's.  The engineer
> before me decided to try the new technology Philly-strand guy lines on th
>   AM directional towers because they had constant problems with the original
> segmented steel guy wires/egg insulators constantly arcing over whenever
> there was a thunderstorm in the area.  To attach the Philly-strand, they
> used traditional metal saddle clamps on this early ( somewhat experimental )
> Philly-strand installation.  It was a real neat looking job with 3 clamps 3
> inches apart and all within 8 inches of the ends of the Philly Strand.  Just
> like you see on steel guy lines.
>
> It was written up in Broadcast Engineering Magazine with lots of pictures as
> the wave of the future for AM broadcast guyed towers.
>
> In reality, it didn't work well because we were constantly having to
> re-attach the lines because the inner strands pulled short inside the outer
> sheath, leaving just the outer sheath holding the tower up!  ( nude towers,
> no antennas on top ).    It didn't take long before we realized that we had
> to use a lot more foldback length and a lot more clamps!  We went with 36"
> foldbacks with six clamps evenly spaced to keep things from pulling apart!
> That worked and stayed together for the remaining 10 years I worked there.
> Yes, we had to insert 6 feet of steel line at the anchor points to make up
> for the lost length at each end of each guy lines.
>
> No guarantees, but that was my experience with the original Philly-strand.
> If you decide to keep it, be very careful and inspect it frequently!  They
> don't make that original Philly-strand for a good reason.
>
> 73
>
> Lloyd - N9LB
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces at contesting.com]On Behalf Of Grant
> Saviers
> Sent: Monday, January 13, 2014 1:15 PM
> To:topband at contesting.com
> Subject: Topband: Ends for older Phillystran
>
>
> Hoping for some help to be able to use some older Philly.  The factory
> tells me their grips won't work on "parallel strand" construction which
> is what I have, epoxy potted sockets are required.  However, they only
> pot at the factory (liability etc etc) which means tossing 6 x 300' of
> 5/8" 45klb ultimate strength.  Newer Philly (post 1991) is constructed
> of 7 twisted strands, something like 7x19 wire rope (not exactly the
> same, but similar) and the PVC sheath transfers the load effectively
> with the Philly guy grips.
>
> Any reports of success with field potting, materials, how to do it, and
> where ends can be obtained (or a drawing, I will machine them) would be
> appreciated.  I would have a load test done on each guy post potting.
>
> Grant KZ1W
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