Re: Topband: Ends for older Phillystran
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:lloydb...@charter.net] Sent: Monday, January 13, 2014 5:15 PM To: Grant Saviers;topband@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-boun...@contesting.com]On Behalf Of Grant Saviers Sent: Monday, January 13, 2014 1:15 PM To:topband@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 _ Topband Reflector Archives -http://www.contesting.com/_topband _ Topband Reflector Archives -http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
I have been hesitant to talk about this, for fear of incurring the wrath of the purists, but since Lloyd went first... I obtained a quantity of new-old-stock of the old 15000 pound Phillystran a few years ago. I had the same issue - the ends. It dawned on me that in my application, the maximum force the Philly would ever be subjected to was 2000-3000 pounds. Thus, my ends only needed to handle that load, not the full 15000 pounds. I went with 3 Crosby clamps on each end. After 2 years, I don't see any sign of the inner strands being pulled inward. Your mileage may vary. 73, Steve, N2IC On 01/13/2014 04:15 PM, Lloyd Berg - N9LB wrote: 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 the 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-boun...@contesting.com]On Behalf Of Grant Saviers Sent: Monday, January 13, 2014 1:15 PM To: topband@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 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
On 01/13/2014 04:15 PM, Lloyd Berg - N9LB wrote: 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 the 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 Lloyd, Was this the Phillistran that did not have the inner strands in a rope configuration or were they just straight fibers? Thanks, Jim - KR9U _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
To clarify, it was the original straight fiber version of Philly-strand that we had problems with at WDAE AM 1250 KHz. We were able to successfully compensate for the inner strand slippage characteristic by adopting a greatly lengthened foldback, large thimbles, and lots of clamps. If you do use the original straight strand version Philly-strand, just be aware of the slippage issue, adopt a more thorough system of clamping, and inspect it frequently! -Original Message- From: Topband [mailto:topband-boun...@contesting.com]On Behalf Of James Wolf Sent: Tuesday, January 14, 2014 8:23 AM To: topband@contesting.com Subject: Re: Topband: Ends for older Phillystran On 01/13/2014 04:15 PM, Lloyd Berg - N9LB wrote: 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 the 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 Lloyd, Was this the Phillistran that did not have the inner strands in a rope configuration or were they just straight fibers? Thanks, Jim - KR9U _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
I would never design and especially never test for the maximum steady working load at a wind speed. The shock load of a bounce can strip the ends. I had a friend who lost a tower from a straight line wind in a normal thunderstorm because the outer layer stripped off. He used three saddle clamps. I told him he should have wrapped the insulator (he used insulators to transistion to steel) two or three turns before clamping. This is not much different than getting hold of copperweld twinlead, or anything else with a soft outside and hard core. Has anyone thought of a long rectangular bar with multiple champhered holes, with the Phillystran woven through from side-to-side? With enough weaves, this should self-tension with just a single clamp on the far end. Regardless, I would test pull and see what breaks first at what tension. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
The bar idea would probably significantly reduce the allowable tension on the cable, similar to what knotting does, due to the force at each bite point weakening the cable. I suppose if the cable was sufficiently oversized this wouldn't pose a problem, but I'd certainly expect such a clamping method to effectively reduce the allowable tension significantly below the normal rated load. I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. Those grips work by compression of the cable they are grabbing, and it's a fairly even pressure over the length of the gripped area. If one could be found that was the correct diameter for the cable being used it might be worth a shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL! He's also correct that dynamic loading is much worse than static loading. Wind causes vibration in towers and guys and that can cause your clamps to loosen over time, especially if they were marginal to begin with. -Bill Has anyone thought of a long rectangular bar with multiple champhered holes, with the Phillystran woven through from side-to-side? With enough weaves, this should self-tension with just a single clamp on the far end. Regardless, I would test pull and see what breaks first at what tension. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
We sailors would wrap a line twice around the eye and then leave a longer tail and clamp that with some space between each clamp. The increased friction of 2 wraps around an eye/block/winch substantially reduces the pull on a knot, cleats or (in this case) clamps. It could be that the phillystran needs to be wrapped around something with a larger radius than the eye however… not sure of the engineering on that point. So you might need a “thimble” in the set up. On Jan 14, 2014, at 10:04 AM, Bill Wichers bi...@waveform.net wrote: The bar idea would probably significantly reduce the allowable tension on the cable, similar to what knotting does, due to the force at each bite point weakening the cable. I suppose if the cable was sufficiently oversized this wouldn't pose a problem, but I'd certainly expect such a clamping method to effectively reduce the allowable tension significantly below the normal rated load. I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. Those grips work by compression of the cable they are grabbing, and it's a fairly even pressure over the length of the gripped area. If one could be found that was the correct diameter for the cable being used it might be worth a shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL! He's also correct that dynamic loading is much worse than static loading. Wind causes vibration in towers and guys and that can cause your clamps to loosen over time, especially if they were marginal to begin with. -Bill Has anyone thought of a long rectangular bar with multiple champhered holes, with the Phillystran woven through from side-to-side? With enough weaves, this should self-tension with just a single clamp on the far end. Regardless, I would test pull and see what breaks first at what tension. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
Thanks to all who provided info and suggestions. I plan to run some tests, starting with a modification to my 20T H frame press so I can tension test specimens up to 10k lbs or so and measure force with a simple Dillon mechanical 5k# force gauge I have. A lever arm will give me 2x and maybe 4x tension. I've also talked with West Coast Wire Rope and Rigging here in Seattle, they have a 5k to 500k# pull stand for up to 180' long cables that costs $150 per test hour. 6 to 8 tests can be run in that time for short/small cables (my home test samples will be 4 to 5' long). If I can't break a test specimen, then they will. With my press setup I can leave the tension on for a few days and check for slippage and cycle the test to some max tension value. It appears that one solution to be able to use old Phillystran is to use wire rope clips and HD thimbles at the right quantity and tightening torque. So, I plan an experiment with differing numbers of clips, 4 to 6, and tightening torques (5/8 clips) from 35 to 95 ft-lbs (95 is the recommended wire rope value). I think 3/4 heavy duty thimbles are the correct size for all experiments. So the plan is to test 3 corner conditions assemblies to 10k# then to 20k# (if I can), measuring the slippage or failure each time and then pull test whatever survives to failure at WCWR. (I hope I can watch!) Since new Phillystran (11.2k# vs what I have is 45k#) will set me back well over $4k for this tower (65G, 150'), this seems a reasonable way to find out if what I have can be made reliable for $200 of steel, clips, and some welding. So, if you know more about designing a such a test or clips on Phillystran let me know. Tom's multi-turn wrap termination is an interesting idea, it works for line and monofilament on fish-hooks. Any suggestions on what the thimble would look like? Kevlar is bend radius sensitive and fatigue prone. Grant KZ1W On 1/14/2014 7:54 AM, Tom W8JI wrote: I would never design and especially never test for the maximum steady working load at a wind speed. The shock load of a bounce can strip the ends. I had a friend who lost a tower from a straight line wind in a normal thunderstorm because the outer layer stripped off. He used three saddle clamps. I told him he should have wrapped the insulator (he used insulators to transistion to steel) two or three turns before clamping. This is not much different than getting hold of copperweld twinlead, or anything else with a soft outside and hard core. Has anyone thought of a long rectangular bar with multiple champhered holes, with the Phillystran woven through from side-to-side? With enough weaves, this should self-tension with just a single clamp on the far end. Regardless, I would test pull and see what breaks first at what tension. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
Large guy insulators may pass two turns of your Phillystran. They're always available on ebay for reasonable prices. If it would help, I have several guy insulators with one inch diameter holes that I never expect to use. 73 Frank W3LPL - Original Message - From: Grant Saviers gran...@pacbell.net To: Tom W8JI w...@w8ji.com, topband@contesting.com Sent: Tuesday, January 14, 2014 5:31:06 PM Subject: Re: Topband: Ends for older Phillystran Thanks to all who provided info and suggestions. I plan to run some tests, starting with a modification to my 20T H frame press so I can tension test specimens up to 10k lbs or so and measure force with a simple Dillon mechanical 5k# force gauge I have. A lever arm will give me 2x and maybe 4x tension. I've also talked with West Coast Wire Rope and Rigging here in Seattle, they have a 5k to 500k# pull stand for up to 180' long cables that costs $150 per test hour. 6 to 8 tests can be run in that time for short/small cables (my home test samples will be 4 to 5' long). If I can't break a test specimen, then they will. With my press setup I can leave the tension on for a few days and check for slippage and cycle the test to some max tension value. It appears that one solution to be able to use old Phillystran is to use wire rope clips and HD thimbles at the right quantity and tightening torque. So, I plan an experiment with differing numbers of clips, 4 to 6, and tightening torques (5/8 clips) from 35 to 95 ft-lbs (95 is the recommended wire rope value). I think 3/4 heavy duty thimbles are the correct size for all experiments. So the plan is to test 3 corner conditions assemblies to 10k# then to 20k# (if I can), measuring the slippage or failure each time and then pull test whatever survives to failure at WCWR. (I hope I can watch!) Since new Phillystran (11.2k# vs what I have is 45k#) will set me back well over $4k for this tower (65G, 150'), this seems a reasonable way to find out if what I have can be made reliable for $200 of steel, clips, and some welding. So, if you know more about designing a such a test or clips on Phillystran let me know. Tom's multi-turn wrap termination is an interesting idea, it works for line and monofilament on fish-hooks. Any suggestions on what the thimble would look like? Kevlar is bend radius sensitive and fatigue prone. Grant KZ1W On 1/14/2014 7:54 AM, Tom W8JI wrote: I would never design and especially never test for the maximum steady working load at a wind speed. The shock load of a bounce can strip the ends. I had a friend who lost a tower from a straight line wind in a normal thunderstorm because the outer layer stripped off. He used three saddle clamps. I told him he should have wrapped the insulator (he used insulators to transistion to steel) two or three turns before clamping. This is not much different than getting hold of copperweld twinlead, or anything else with a soft outside and hard core. Has anyone thought of a long rectangular bar with multiple champhered holes, with the Phillystran woven through from side-to-side? With enough weaves, this should self-tension with just a single clamp on the far end. Regardless, I would test pull and see what breaks first at what tension. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
The bar idea would probably significantly reduce the allowable tension on the cable, similar to what knotting does, due to the force at each bite point weakening the cable. I suppose if the cable was sufficiently oversized this wouldn't pose a problem, but I'd certainly expect such a clamping method to effectively reduce the allowable tension significantly below the normal rated load. I wouldn't do anything as tight as a knot, especially when both surfaces have significant yield. The holes would have to be chamfered to prevent cutting through the jacket. It wouldn't be much different than an insulator if done correctly. It is all about not making the short turn radius a knife. I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. Those grips work by compression of the cable they are grabbing, and it's a fairly even pressure over the length of the gripped area. If one could be found that was the correct diameter for the cable being used it might be worth a shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL! He's also correct that dynamic loading is much worse than static loading. Wind causes vibration in towers and guys and that can cause your clamps to loosen over time, especially if they were marginal to begin with. There has to be considerable pressure on the jacket squeezing it into the inner fiberglass. I'd be reluctant to use a grip on something that has a tendency to slide. I don't think it will squeeze hard enough. The newer Phillystran has much less tendency to have the jacket slide over the center. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
As a very crude analogy what you want to be able to do is use a steel cable from the anchor through the middle of something like an automobile wheel, Then the Phillystran wants to take a couple of lazy turns around the rim of the wheel and then get clamped to itself. While there are probably better engineered alternatives to the auto wheel the idea is that the turn be of a large smooth radius and have a high total friction such that the clamps don’t actually hold against much pull. If you look at old sailing ships that’s how they are rigged… with big wooden thimble blocks. On Jan 14, 2014, at 12:02 PM, Tom W8JI w...@w8ji.com wrote: The bar idea would probably significantly reduce the allowable tension on the cable, similar to what knotting does, due to the force at each bite point weakening the cable. I suppose if the cable was sufficiently oversized this wouldn't pose a problem, but I'd certainly expect such a clamping method to effectively reduce the allowable tension significantly below the normal rated load. I wouldn't do anything as tight as a knot, especially when both surfaces have significant yield. The holes would have to be chamfered to prevent cutting through the jacket. It wouldn't be much different than an insulator if done correctly. It is all about not making the short turn radius a knife. I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. Those grips work by compression of the cable they are grabbing, and it's a fairly even pressure over the length of the gripped area. If one could be found that was the correct diameter for the cable being used it might be worth a shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL! He's also correct that dynamic loading is much worse than static loading. Wind causes vibration in towers and guys and that can cause your clamps to loosen over time, especially if they were marginal to begin with. There has to be considerable pressure on the jacket squeezing it into the inner fiberglass. I'd be reluctant to use a grip on something that has a tendency to slide. I don't think it will squeeze hard enough. The newer Phillystran has much less tendency to have the jacket slide over the center. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
Another alternative is to wrap two turns of the Phillystran around a short length of three inch diameter steel pipe or tubing. Then pass a large shackle through the tubing to fasten it to the steel cable. Cut the tubing to fit the shackle, so that the Phillystran can't slip off the end of the tubing. 73 Frank W3LPL - Original Message - From: Ashton Lee ashton.r@hotmail.com To: Tom W8JI w...@w8ji.com Cc: n...@arrl.net, Bill Wichers bi...@waveform.net, Group Topband topband@contesting.com Sent: Tuesday, January 14, 2014 7:11:06 PM Subject: Re: Topband: Ends for older Phillystran As a very crude analogy what you want to be able to do is use a steel cable from the anchor through the middle of something like an automobile wheel, Then the Phillystran wants to take a couple of lazy turns around the rim of the wheel and then get clamped to itself. While there are probably better engineered alternatives to the auto wheel the idea is that the turn be of a large smooth radius and have a high total friction such that the clamps don’t actually hold against much pull. If you look at old sailing ships that’s how they are rigged… with big wooden thimble blocks. On Jan 14, 2014, at 12:02 PM, Tom W8JI w...@w8ji.com wrote: The bar idea would probably significantly reduce the allowable tension on the cable, similar to what knotting does, due to the force at each bite point weakening the cable. I suppose if the cable was sufficiently oversized this wouldn't pose a problem, but I'd certainly expect such a clamping method to effectively reduce the allowable tension significantly below the normal rated load. I wouldn't do anything as tight as a knot, especially when both surfaces have significant yield. The holes would have to be chamfered to prevent cutting through the jacket. It wouldn't be much different than an insulator if done correctly. It is all about not making the short turn radius a knife. I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. Those grips work by compression of the cable they are grabbing, and it's a fairly even pressure over the length of the gripped area. If one could be found that was the correct diameter for the cable being used it might be worth a shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL! He's also correct that dynamic loading is much worse than static loading. Wind causes vibration in towers and guys and that can cause your clamps to loosen over time, especially if they were marginal to begin with. There has to be considerable pressure on the jacket squeezing it into the inner fiberglass. I'd be reluctant to use a grip on something that has a tendency to slide. I don't think it will squeeze hard enough. The newer Phillystran has much less tendency to have the jacket slide over the center. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
I'm actually a little surprised a dead end / preform isn't supposed to be used with the straight-strand version of the cable. This discussion really belongs on TowerTalk, but If the straight-strand cable is bent around something, be it an insulator, guy grips, woven in and out of holes, etc, the fibers within the cable will not share the load equally. Not having equal loads within the Phillystran cable derates its designed strength, probably by more than 50%. The older, straight-strand, cables made use of a cone-shaped aluminum basket at each end. IIRC, the cable is inserted into the pointed end (tip) of the basket and pulled out the open end. Tape is wrapped around the cable a few inches from the end, then the sheath is removed down to the tape. The individual fibers are then combed and fanned out. The cable is pulled back into the basket, wedging the tape into the tip. That makes a liquid-tight seal. A homebrew jig is used to hold the basket upright while a potting compound is poured into the basket and allowed to harden. 73, Charlie, N0TT _ Topband Reflector Archives - http://www.contesting.com/_topband
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 the 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-boun...@contesting.com]On Behalf Of Grant Saviers Sent: Monday, January 13, 2014 1:15 PM To: topband@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 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ends for older Phillystran
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:lloydb...@charter.net] Sent: Monday, January 13, 2014 5:15 PM To: Grant Saviers; topband@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 the 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-boun...@contesting.com]On Behalf Of Grant Saviers Sent: Monday, January 13, 2014 1:15 PM To: topband@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 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
