The AM Forum
March 28, 2024, 02:25:06 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Antenna rope  (Read 17002 times)
0 Members and 1 Guest are viewing this topic.
K6JEK
Contributing
Member
*
Offline Offline

Posts: 1189


RF in the shack


« on: July 05, 2011, 02:44:39 AM »

The dipole is down.  The Dacron UV resistant 3/16" antenna rope from Wireman broke.  It looks like something sharp got it, maybe a critter (*).  I've been using this stuff for awhile.  It does seem to last, or did, anyway.

Anyone have a different favorite?   Anything tougher?

* This rope was looped through a pulley at 50' up in a redwood tree to support one end of the 75M dipole.  The other end reached nearly to the ground where it was tied to counterweights. I climbed that tree to put it up and am not relishing doing that again.
Logged
K3ZS
Member

Offline Offline

Posts: 1037



« Reply #1 on: July 05, 2011, 09:38:16 AM »

I have been using 3/8' double braided dacron for 10 years without breakage.  Where it is tight, there has been no wear,  where the excess is coiled up, the critters have been eating it.   Cut ends of the rope should be burned with a lighter  to keep it from fraying.   I moved one section of the antenna and cut off the excess rope so it could be used again without being critter food.   If I have to lower that end I will tie another section to it to lower it and remove it again after raising it.
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #2 on: July 05, 2011, 10:42:44 AM »

ooops!! I better start checking my stuff out cuz another installation had the 3/16 and it became brittle and broke recently. About 5yrs old also.
The 5/16 stuff is still manageable,,, a little more scrote.
3/8 gets into serious rope!!!!
Logged

Fred KC4MOP
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #3 on: July 05, 2011, 11:51:47 AM »

http://www.synthetictextilesinc.com/supportham.html

This is the stuff I've used for 25 years.   I have some that has been up since 1986 and still looks good. It can be untied and reused easily, even with ice, snow or rain on it. No UV problems.  Double braided Polyester. [Dacron]


Polyester (PET)
"Polyethylene terephthalate, the most common type of polyester, is the most common fiber used in sailcloth; it is also commonly referred to by the brand name Dacron. PET has excellent resiliency, high abrasion resistance, high UV resistance, high flex strength and low cost. Low absorbency allows the fiber to dry quickly."  -  WikiPedia


Get the 3/16" stuff for most jobs, [supported in the center]  but use the 5/16" or larger for bigger jobs. [no center support]

I think the "Rope Man"  sells it too.  The manufacturer is in CA and will sell directly.

** For the tree supports, use 3/16" galvanized aircraft cable or even 7 strand steel guy cable to go thru the limbs. It will never chaff and break. Then use a pulley for the rope on the end of the wire cable.   The guy cable is smoother and will not saw itself into the limb like the aircraft cable will. Any type of rope will eventually chaff and break when rubbing a tree limb in the wind. [and critters]

T
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10057



« Reply #4 on: July 05, 2011, 12:22:17 PM »

I used about 900 ft. of this running to the wooden poles to hold up the ends of my dipole, installed about 25 years ago after lightning had wiped out ceramic strain insulators installed on copperweld. Still in service.
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
K6JEK
Contributing
Member
*
Offline Offline

Posts: 1189


RF in the shack


« Reply #5 on: July 05, 2011, 01:39:48 PM »

I used about 900 ft. of this running to the wooden poles to hold up the ends of my dipole, installed about 25 years ago after lightning had wiped out ceramic strain insulators installed on copperweld. Still in service.
Which one, Don?  There seem to be several different ones on that website unless I'm misunderstanding it.
Logged
KM1H
Contributing
Member
*
Offline Offline

Posts: 3519



« Reply #6 on: July 05, 2011, 02:31:17 PM »

Ive been using the same as JJ since about as long when it was first brought to the attention of the ham community in the YCCC newsletter.

Unless it was rubbed on a branch it doesnt look any different than when I bought it and a lot has been at 2 different QTH's.

The current price is higher than necessary IMHO and for the new 160/80/75 inverted vee at 170' I put up last fall I used what I needed from 1000' of double braided black Dacron 5/16 from Fleabay
Logged
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10057



« Reply #7 on: July 05, 2011, 03:21:10 PM »

I used about 900 ft. of this running to the wooden poles to hold up the ends of my dipole, installed about 25 years ago after lightning had wiped out ceramic strain insulators installed on copperweld. Still in service.
Which one, Don?  There seem to be several different ones on that website unless I'm misunderstanding it.

I would use the one designed to replace metallic guy  wires  for towers.  Looks like they make a much wider variety of products than when I bought mine. They have also improved (?) the product.  Mine consist of a bundle of fibres enclosed in a jacket that resembles RG-58. The fibre strands at the ends were  fanned out like a paint brush and potted in a hollow assembly using some kind of two-part epoxy compound. Nowadays, they are still enclosed in a similar jacket, but the strands are braided similar to wire rope, just like regular 7-strand guy cable, and cable clamps or special pre-form Guy Grips are used to terminate the ends, just like with metallic guy cable.

The stuff isn't cheap, but I wanted something that would last a long time.  The metal guy wires on my tower are now getting rusty, and I may have to replace them before I ever need to replace that plastic cable.

I had to use the next size larger than what I really needed, because even though they manufactured a lighter 1200 lb. strength variety, none of their dealers that I could find carried it in stock.  The heavier stuff was more expensive, but still very light in weight, and I have always liked to use overkill on my projects anyway. That whole 900 ft. roll probably weighed less than 10 lbs.
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
KM1H
Contributing
Member
*
Offline Offline

Posts: 3519



« Reply #8 on: July 05, 2011, 04:19:48 PM »

I almost lost a 100' tower due to Phillystran around 86-87 and it was the early version Don mentioned.

The problem was that I used the tower as a 160M shunt fed vertical with a 10/15/20 Christmas tree of 4 el yagis on top.

Well silly me cut out several pine tree branches to give a clear shot to the anchor but didnt figure on snow load and winds. It was pure luck I saw the cuts during a rotator swap/repair trip up the tower and quickly changed over to steel after cutting back the PS to about 10' long at the top of the tower.

The towers are in the woods here also so all guying is 1/4" EHS with Johnny Ball insulators, no more fooling around.

Carl
Logged
K5UJ
Contributing
Member
*
Offline Offline

Posts: 2845



WWW
« Reply #9 on: July 05, 2011, 08:03:04 PM »

At the last hamfest I went to one of the guys from one of our 1-A AM outlets here and I started talking about guying (I have no idea how we got on that topic but it was one of those anything and everything morning gab fests) and he said he never felt comfortable using phillystran for the station tower.   Always has gone with steel broken up with insulators.   

But dacron.  I have always used the 3/16" stuff no probs, but I don't have heavy duty loads here--there's a long period of stretching during which you have to retension everything but once it stretches out and gets weathered it seems tough as nails. 

I'd avoid any "dacron" or supposedly UV treated rope at hamfests.  I've seen this off-brand rope and cable for sale at the fests and that old saying about, if it seems too good to be true....came to mind.  Whatever you wind up with, I'd get material from an established vendor who says in no uncertain terms that it is what it is, and save money on other things.
Logged

"Not taking crap or giving it is a pretty good lifestyle."--Frank
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10057



« Reply #10 on: July 05, 2011, 11:51:00 PM »

I almost lost a 100' tower due to Phillystran around 86-87 and it was the early version Don mentioned.

The problem was that I used the tower as a 160M shunt fed vertical with a 10/15/20 Christmas tree of 4 el yagis on top.

Well silly me cut out several pine tree branches to give a clear shot to the anchor but didnt figure on snow load and winds. It was pure luck I saw the cuts during a rotator swap/repair trip up the tower and quickly changed over to steel after cutting back the PS to about 10' long at the top of the tower.

The towers are in the woods here also so all guying is 1/4" EHS with Johnny Ball insulators, no more fooling around.

You don't want anything to abrade the Phillystran jacket. At least on the old stuff like I used, it is very fragile.  They recommend using a length of steel guy cable at the bottom ends to avoid damage from grass  fires, and to make the plastic cable inaccessible to animals and vandals. When I got mine, it was coiled up in about a 3' diameter roll.  While uncoiling it, I accidentally let a kink develop, and when I pulled it tight to measure out the length for each of the two pieces, the jacket split right at the kink along about a one-inch length where I could see exposed yellow fibre. I was ready to put it up right then and didn't feel like stopping the project to order more hardware to make a complete splice at the damaged spot, so I wrapped the split in the jacket with Coax-Seal, put it up and hoped for the best. The Coax-Seal seemed to adhere to the Phillystran just like it adheres to coax, and after 25 years it has not come in two, so evidently my fix worked.

Of course, if it breaks, the only thing that will happen is that one leg of the dipole will come down.  The tower is securely guyed with EHS steel guy cable broken up with johnny-balls.
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
K5UJ
Contributing
Member
*
Offline Offline

Posts: 2845



WWW
« Reply #11 on: July 06, 2011, 05:59:32 AM »

The guy at the radio station told me that the way the transfer from ps to steel near the anchor is done is critical.  If it isn't done just right --- ooops, goodbye tower.   They were trying ps and that union wasn't done right and they found it during tension testing and that ended the ps experiment.
Logged

"Not taking crap or giving it is a pretty good lifestyle."--Frank
W3SLK
Member

Offline Offline

Posts: 2651

Just another member member.


« Reply #12 on: July 06, 2011, 09:06:20 AM »

Well now. I have been using the stuff that came with the support bag of my mil-spec antenna support. Its the olive drab green stuff and has been up in the sun for over 5 years with no noticable degradation. I also have used braided poly to support the ends in the trees. This has been in use for close to 20 years. I've checked it at each QTH change and it still looks like the day I placed it there.
Logged

Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
W0BTU
Member

Offline Offline

Posts: 230



WWW
« Reply #13 on: July 06, 2011, 10:43:54 AM »

I have been using 3/8' double braided dacron for 10 years without breakage.  Where it is tight, there has been no wear,  where the excess is coiled up, the critters have been eating it.  

As K3ZS pointed out, critters are attracted to Dacron and chew on it.

I personally would never use Dacron rope. I have simply heard too many stories of squirrels bringing down dipoles (and worse) by chewing through Dacron rope, and we have lots of squirrels here.

EDIT: I've never heard of an animal chewing through nylon rope, which is all I use for supporting wire antennas. For a tower, I would only use 3/16" EHS.

Logged

73 Mike 
www.w0btu.com
WD8BIL
Contributing
Member
*
Offline Offline

Posts: 4409


« Reply #14 on: July 06, 2011, 11:09:45 AM »

Quote
I've never heard of an animal chewing through nylon rope, which is all I use.

They don't chew thru 1/8" and 3/16" aircraft cable either!
Only problem I've had with it is it sawing through the limbs! Undecided
Logged
WA1GFZ
Member

Offline Offline

Posts: 11152



« Reply #15 on: July 06, 2011, 11:31:41 AM »

Mikey,
I also like the OD green much better. I have some in the woods behind the yard up since '83. I also ran into some black stuff even better. A little stiffer but it will saw itself through a tree without breaking.
Logged
k4kyv
Contributing Member
Don
Member

Offline Offline

Posts: 10057



« Reply #16 on: July 06, 2011, 11:41:13 AM »

The guy at the radio station told me that the way the transfer from ps to steel near the anchor is done is critical.  If it isn't done just right --- ooops, goodbye tower.   They were trying ps and that union wasn't done right and they found it during tension testing and that ended the ps experiment.

I would use a regular johnny-ball guy insulator, terminate the ps through one hole, and terminate the steel section through the other, in normal strain insulator fashion. I would trust the braided stuff with clamps more than I would the older style potted end terminations for holding up a tower. Someone told me some time ago that's the reason they changed over; there  had been several reported failures of the potted terminations.

I suspect at the tower he was talking about, someone did something stupid like using the johnny ball in the same fashion as a regular antenna insulator so that if it broke, the guy cable would just fall apart, or by merely looping the cables together with nothing in between.

Another no-no is to use oversize metallic guy cable. The problem with that is that if the heavier guy wire is tightened to recommended tension, it may put too much downward thrust on the tower, causing it to overload and collapse in heavy wind. You can probably get away with using 1/4" cable where 3/16" is called for, but I wouldn't go any heavier than that. Probably the reason most  people would use heavier cable is that they already have it on hand, since the larger cable is more expensive. It would not be a good idea to purchase oversize cable brand new for the purpose of "overkill".

I didn't even tension my guys to the full recommended 10% of breaking strength, since that made them seem awfully tight.  I put up the tower in hot weather, so in the dead of winter on cold nights, the tension would have been still greater.  I used the intuitive approach and tensioned them to what felt right and appeared to have the right amount of sag. In cold wx they still seem very tight.

I had one of my OWL termination insulators to break during a cold snap (no pun intended). I had tightened them too much during the summer and the insulator (an ordinary dog-bone ceramic antenna insulator) pulled in two.  Luckily it was at the bottom end and not the top end 119' up.  I immediately loosened the other one, and after repairing the broken one, maintained less tension than before.

I suppose to be technically correct, one would go out and re-set the guy wire tension twice a year, in the spring and fall, but that would be a lot of extra work, and even a worse nuisance than fiddling with the clocks and having vehicles inspected twice a year. They might actually do that at some larger installations like the Blaw-Knox towers at WLW and WSM. (The guy anchor assemblies at WLW are quite interesting.  I wish I had brought along my camera the day we visited.)
Logged

Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

- - -
This message was typed using the DVORAK keyboard layout.
http://www.mwbrooks.com/dvorak
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #17 on: July 06, 2011, 11:43:10 AM »

Quote
I've never heard of an animal chewing through nylon rope, which is all I use.

They don't chew thru 1/8" and 3/16" aircraft cable either!
Only problem I've had with it is it sawing through the limbs! Undecided


Yes, I've seen critter damage on Dacron rope coiled on or near the ground too.  The idea is to use the Dacron rope only for the mid-air support. If it goes thru a pulley, then when it comes to the ground add a post and hang the rope hank there.  I've never had an isolated hank on a post critter-chewed. Worst case, add a squirrel guard plate.

As for the aircraft cable - I use it a lot when going to a tower, but it does saw thru tree limbs. A much better choice is the smooth, 7-strand EHS guy cable thru a tree limb. That stuff is smooth and slides easily. I use left over 3/16" or 1/4" stuff.   I use a bow and arrow to get it thru a high limb, then add a pulley at the end of the cable for the rope to pull thru.  The only risk is the pulley chaffing the rope.  If the load is heavy, then a direct tie to the 1/4" steel cable is in order and the dipole is lowered by slacking the steel cable from the ground thru the tree limb.

A dipole installation can be made bullet proof for ice, wind or critters using these techniques.  Hanging the dipole at the center is the key to longevity while the ends are relatively loose.  

But with no dipole center support using trees takes a lot of planning and thought if expected to stay up for years.  We have to work with what we have available.

T
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
W4AAB
Member

Offline Offline

Posts: 314


« Reply #18 on: July 06, 2011, 07:30:57 PM »

I am planning to use parachute cord, which I bought at a military surplus store.
Logged
K5UJ
Contributing
Member
*
Offline Offline

Posts: 2845



WWW
« Reply #19 on: July 06, 2011, 07:51:13 PM »

The guy at the radio station told me that the way the transfer from ps to steel near the anchor is done is critical.  If it isn't done just right --- ooops, goodbye tower.   They were trying ps and that union wasn't done right and they found it during tension testing and that ended the ps experiment.

I would use a regular johnny-ball guy insulator, terminate the ps through one hole, and terminate the steel section through the other, in normal strain insulator fashion. I would trust the braided stuff with clamps more than I would the older style potted end terminations for holding up a tower. Someone told me some time ago that's the reason they changed over; there  had been several reported failures of the potted terminations.

I suspect at the tower he was talking about, someone did something stupid like using the johnny ball in the same fashion as a regular antenna insulator so that if it broke, the guy cable would just fall apart, or by merely looping the cables together with nothing in between.


It wasn't real clear to me how the ps to steel transition was done, but I got the impression it was some sort of specialized hardware made for ps and not what you describe Don.   It seemed that it was tricky to get right and the station engineer decided to not risk a 190 degree hot tower.    To me although no where near any tower expert, it seems that if steel broken up with johnny balls gets the job done without distorting the pattern, then why fix it if it's not broken.   Where I have seen ps put to good use is on side mounted FMs where they go to ps a bit below the bays, and past them up to the top of the tower.  Steel below and ps in the RF where steel would cause all kinds of probs.   
Logged

"Not taking crap or giving it is a pretty good lifestyle."--Frank
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #20 on: July 06, 2011, 08:56:12 PM »

The older Phillystran required potted ends.  The Philly strands were spread out thin and put into a metal "cup" and the epoxy was poured in. The other end of the cup held a place for a steel pin to interface to the EHS guy cable.  The epoxy was a rather barbaric and expensive method and was later replaced by Philly that could be tied into a knot. I don't know what the recommended simpler interface is for the newer Philly but epoxy and cups are no longer needed.  I have used newer style Philly simply tied to a large johny-ball as the interface to the steel EHS cable. With a huge strain as a 75M wire Yagi boom cable, it held up for years like this.

In the end, I like towers constructed with ALL steel - this means EHS guy cable thruout. I don't like the idea of someone with a step ladder being able to drop the tower with a pair of sissors - or a lighter.  Or lets say a big microburst came along and carried sharp scrap metal into the Philly. These are remote possibilities, granted, but all steel makes me more confident.  

To the credit of the Philly, considering the expense of a complete EHS guy and johnny-ball assembly, the medium rated Phillystran is probably close in price - plus it is surely superior when it comes to RF antenna influences.  

T

Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
KM1H
Contributing
Member
*
Offline Offline

Posts: 3519



« Reply #21 on: July 06, 2011, 09:13:03 PM »

Ive been using 1/4" EHS on 25G and 45G since the CATV installers came thru the area in 83 and dropped of whatever hardline, guy wire and fittings which were left over; that was the good old days. Rohn blessed the 1/4". There is at least one more full reel remaining and part will be used for some reguying of all towers soon.

On the 180' 45G tower the concrete base plate sits on a Rohn pier pin and the guys and torque arms do all the work. When I had that loaded with 4/4 on 40 and 4/4/4/4 on 20 a good blow would move the whole tower around like a big torque tube with the least effect at the base. Ive been on top many times in a 40-50mph gusts and it was an interesting feeling.
Logged
K6JEK
Contributing
Member
*
Offline Offline

Posts: 1189


RF in the shack


« Reply #22 on: July 07, 2011, 11:12:39 AM »

What do you think, guys?  Will the Kevlar core, Dacron sheath stuff be better or worse under attack?  All the failures I've had with the Dacron stuff have been when it got nicked.  That's curtains, as near as I can tell.  If a squirrel or some other sharp toothed vandal chomps on it,  I'd better spot it and replace it while it's easy or I'll be fiddling around with an antenna on the ground.

The Kevlar stuff, from what I've read, has just the same Dacron sheath.  The core is stronger under tension but how about under chomping?  More delicate or less?

http://www.radioworks.com/crope.html

BTW.  None of this is over the branch stuff.  I climbed the darned tree and installed a marine pulley up there with a wide Dacron ribbon thinking, that's the ticket.  That's the weak point in the arrangement and I've really taken care of it.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.1 seconds with 19 queries.