KILL MY POLE

How to break a Spiderbeam Fiberglass Pole

(without even trying):

Spiderbeam has sold over 15,000 lightweight telescoping poles, ranging in size from 12m (40 ft.) to 26m (85 ft.).   Most have survived without breakage, but a few users have experienced broken poles.

 

Obviously the taller poles break more often than the 12m pole, because they are exposed to stronger winds.

 

I have said for many years now that the 12m pole has proven to be a very robust pole and rarely breaks unless the user does something stupid with it.  

 

I was recently asked to explain some of the stupid things that a user should not do with his/her fiberglass pole.   The list is shown below:

 

Something Stupid:  Attaching the dipole feedpoint too high onto the fiberglass pole.  Lightweight dipoles should be attached down one segment (junction of segments 11 and 12); the clamp may be used to prevent the thin rope attaching the balun to the pole from slipping down the pole.  (i.e., tie it just above the clamp).  CONFUSSING:  THE EYELET on some of our poles.  This eyelet was added to the pole for a special non-ham radio application.  NEVER attach the antenna feedpoint here.   The eyelet may also be used for attaching the end of a wire vertical to, but actually a wire-tie accomplishes the same thing (and is cheaper). 

 

Something REAL Stupid:  Running RG-213 or LMR-400 coax up the pole. 

Instead, always use RG-58/LMR-240/Aircell5/Airborne5 (etc.).

In fact I use RG-174 A/U for most of my portable operations.

 

Something Stupid:  Stringing a dipole or other wire antenna between two Spiderbeam fiberglass poles.  In other words, using these poles for end-supports.  They were never intended to be used for that purpose.  Exception:  an 18m fg pole, with 5 sections removed, can be used as a HD 10m end pole, if you counter-guy it to oppose the force of the antenna pulling on the pole.  (That was just one example, but you get the picture.)

 

Something Stupid:  Using thick wire for the top-hat wires of a top-loaded vertical.  We use #26-AWG, and extend with either 1mm Kevlar rope or our PVDF Monofil line.  We also use tiny, ultra-light insulators between the wires and the extension lines.

 

 

Something Stupid:  (Well in my own case), I tied the 2mm Kevlar guy rope directly to my 18m pole, without using the guy belts. This was erected before we had guy belts in our portfolio.   In a severe ice storm, a large branch of a tree broke off and fell into the guy line.  The point pressure snapped segment 7 at the point the rope was attached. 

Would it have survived if I had used a guy belt?  Who knows?  The guy belt spreads the force over a broader area, greatly reducing the point pressure.

 

Something Stupid:  Most people are more accustomed to working with aluminum or steel masts than fiberglass masts.  They typically extend the mast on the ground, mount the antenna (i.e., dipole with balun and coax running down the pole), then once attached, try to pivot the pole from the horizontal into the vertical by walking it up.   Works fine with metal masts; not with fg poles. 

If the antenna and coax is too heavy, this may break the fg pole.  Instead, stand it up collapsed, pull out one or more segments and attach the antenna at its intended position, then push/telescope the pole up to its full height.

 

Something Stupid:  When I look at the ARRL HANDBOOK, I see the same instructions for building antennas that I saw when I was studying for my license using the 1958 HANDBOOK (in 1960) – bucket of cement and all!   All components:  antenna wire, insulators, ropes, pulleys, etc. were WAY TOO HEAVY for using with today’s lightweight telescoping fiberglass poles. Following these directions when building an antenna to be supported by a lightweight telescoping fiberglass pole is Very Stupid.

 

Instead:  You don’t need and you defenately should NOT use #12-AWG wire for dipoles to be used with fiberglass poles.  #18-AWG, such as our CQ-532 works just fine at any ‘legal’ power limit.

In fact our 404-UL and 807-L work just fine using a wire that is about #26-AWG.

The loss due to the additional D.C. resistance of the thinner wire is peanuts compared to the gain obtained by being able to erect the antenna wire 8 to 10 ft. higher on the pole without breaking it.  A dipole erected higher has a lower take-off angle and less pattern distortion from nearby objects, than low hanging dipoles.

So Another Stupid Thing is: building an antenna as if you were preparing for WW II, as described in many ancient antenna manuals that have not been updated for 60 years . . .  and then mounting them high on a lightweight fg pole.  They can easily break a pole in an ice storm with a bit of wind.  In fact if you don’t erect it properly (i.e., telescope it upwards with the antenna attached), it can easily break the pole when erecting the antenna.

 

Something Stupid:  Over-tightening of the guy ropes, especially with rope attached directly to the pole without use of the guy belts, can place too much point pressure on the pole.   Guy lines should be just barely snug.  They do stretch slightly; yes, even the Kevlar or Dyneema lines stretch slightly.  My lines are usually drooping a little.  They do nothing until the wind starts blowing the pole around.  Then the guy lines limit the amount of travel of the pole.

 

You’ll find more information about building modern antennas on my web site, here:

https://www.dj0ip.de/modern-antennas/

Sorry, its not yet complete.  “Time is my worst enemy.”