GM3WOJ ZL1CT Lattice tower information pages December 2007
Tower problems page - click here to visit the main lattice tower page
Thanks to everyone listed below who sent me information and photos :
From Chris GM3WOJ :
One incident highlighted a design fault in the Fulton K2550 auto-brake winch - this was in year 2000 so the mechanism may have been modified/improved since then. The K2550 is a strong-looking winch, but the pawl of the ratchet mechanism is bolted to a single folded metal web which is pressed/bent at 90o from the metal sheet which is the rear of the winch - this folded web is inherently weak. One day when I turned the winch handle anti-clockwise to start lowering the tower, I was amazed that the metal web bent easily, allowing the pawl to move away from the ratchet completely - I was left holding the whole weight of the tower on the winch handle - if I let go the winch handle would have spun wildly (it was raining heavily and the winch brake pads were wet). I had to untie the catcher-plate rope and lower the tower slowly onto the catcher plate, then use a nearby rope to tie the winch handle until I could repair the problem.
I had another problem where the top section only of my BP80 bent slightly in a storm and could not telescope inside the next section - see photo below :
This meant lowering the tower, with a Hy-Gain 205CAS 5ele 20m yagi on the top, until the 3 lower sections were fully retracted, but the bent top section was still sticking out - scary stuff. I then cautiously tilted the tower slowly over, expecting the top section to buckle at any moment, but luckily it did not and I was able to remove the antenna undamaged and replace the damaged tower section safely.
My worst-ever experience with a Versatower was in 1996 - I learned the hard way that you must guy a tower properly - I had a P60 with a single set of rope guys at the top ('Seasteel' - which is serious rope but difficult to tie properly). One week before our Multi-Multi GM6V effort in CQ WW SSB i.e. late October, a sudden storm struck - the single guys, which were probably not tight enough, could not prevent the tower buckling just above the top of the lowest section. This happened at about 2a.m. - we woke when we heard the crash and I rushed outside in the rain and wind to view the scene of destruction. The worst part was that the head-unit had wedged in the fork of a pine tree - about 15 feet above ground level, and the element tips of the 20m yagi (which was surprisingly undamaged) were sticking out about 4 feet onto the (narrow) public road which borders my QTH ! None of this was anticipated in my planning ! I could not reach the head-unit to remove the antenna, so I had to get out my chain-saw and cut down the pine tree - which fell blocking the road of course - then chop it up into moveable sections, then finally remove the antenna from the head-unit. This took until 5a.m. in the dark, cold, wind and rain - amazingly not one vehicle came along the road in that 3 hours ! Being a determined bunch, the GM6V team rebuilt the tower on the Friday before the contest - we used a 5' section of the damaged middle section as a 'sleeve', which gave us a temporary 40 foot tower. Lots of lessons were learned by me !
From Steve GW4BLE :
The top left-hand photo (taken in 1983) shows the buckled section on a P60 at my old QTH in Risca. The other two photos (taken in 1993) show the aftermath of a storm when the stub mast sheared off - the tangled remains of a KLM KT34XA and other miscellaneous bits of hardware.
From Paul G6PZ :
This top section actually broke in an ice storm. The
aluminium stub-mast bent over so that the top loading was unbalanced and put too
much strain on the tower. I now use a steel pole, a lot heavier but doesn't bend
Two photos of the storm-damaged 2" steel stub-mast
Paul G6PZ working on the damaged tower
From Keith GM4YXI (GM7V) :
2 days before CQ WW SSB 2006, the winch rope on this BP80 broke - damaging the tower and completely destroying a 3-element 20m monobander and a 2-element 40m Moxon.
From Darren G0WCW - photos of M6T from G4PIQ:
4 different views of the same 40m system. What happened was that the wind 'lifted' the top tower section out during the Saturday night of CQ WW SSB 1998. This took with it the three element 40m beam (I think built by Chris G3VHB). Andy, G4PIQ took some of the closer pictures. Interestingly, the lower three sections were more or less untouched and are still in use today.
Andy also took a couple of pictures of the missing top part of the 160m vertical (also snapped the same weekend) :
Another M6T photo
From Alan G3XSV (Photos of EJ2MT IOTA 2006 by G3ZVW and G4CLA) :
I hope these pics cause a chuckle. It wasn't funny at
the time ! We had three Versatower mobile towers on Bere Island for EJ2MT
in the IOTA contest this year. Only the 60ft one survived intact.
Although they were well secured we didn't account for the hurricane force winds that came through just 3 hours before the contest started. Both towers failed in the same way bending the 4th section. The south tower bent at right angles and ejected the top section. It went clear over my car (the blue Jeep in the photo) and landed just a few feet in front of it on the steps of the Martello tower. Luckily nobody was hurt as everyone was taking cover in the Martello tower at the time. The wind was so strong we weren't able to stand up in it.
We believe they failed because we had put too long a pole in the top of the towers to mount the beams. Although the poles were not bent, having the extra leverage above the top guy we think caused the fourth section to bend just above the third section. The top section was bent by the impact.
The wind died down quickly and we actually managed to recover the south tower (remodelled to 60 ft) before the contest started.
The set up was pretty much the same as we had in previous years. There are some more photos on http://ej2mt.g6yb.com/
From Adrian MW1LCR :
A photo of the weld of a crack that formed on the bottom section of the lowest section of a BXI Tower I have.
Apparently, water gets inside the Tower Corner Sections, and freezes, creating cracks. I am considering cutting the bottom inch or so off the tower corner sections to allow water to escape.
(The legs of Versatower tower sections are open at the bottom
end to avoid this problem)
From Don G3BJ :
From Ian GM3SEK :
"We had an anemometer, but the wheel fell off"
Front page news from last week's "Stranraer &
Wigtownshire Free Press, price 60p", reporting on the Hogmanay 2006 storm:
Another storm casualty was a 70ft steel lattice tower which supported a radio-antennae [sic] at Glenamour, Newton Stewart. The mast was bent almost double by a freak gust, with the thick steel looking as though it had melted, and the large antennae on top were plunged into the ground. Repairs or replacements are estimated to cost almost £10,000.
Owner Robin Bellerby [GM3ZYE] said: "We experienced a mini-tornado, and the winds were whipped into circular patterns, rotating at very fast rates -- the mast was rated at well over 100mph"
"I had a wind vane on a nearby building which was bent in two, and a remotely mounted wind gauge which registered a peak gust of 107mph before the vanes blew off."
Robin's tower was a P60 or BP60 with a triband quad. It was guyed, and had survived the previous gales, so Robin left it up... and then the wind literally found a new angle. He is part-way up a valley (not far from Newton Stewart on the Galloway Forest road towards Clatteringshaws Loch) and there seems to have been some kind of wind funnelling effect.
The newspaper photo shows the tower folded at the bottom of the middle section, which is maybe a bit unusual. The bottom of the top section looks like it had remained quite straight, and only got bent when the antennas hit the deck.
A related point about the collapse of guyed towers came up on TowerTalk recently : guys only hold the tower up provided the tower itself remains straight. But K1TTT (who should know) pointed out that once it starts to buckle, the guys will then pull the tower DOWN.
From Steve GW0GEI :
Caption by Paul GW8IZR ( or alternatively "These months of peeing on the cable have paid off I see" )
Had some fun whilst lowering my Tennamast
today to take the log periodic off for repairs after the gales. Suffice to say I
was mighty peed off when the whole lot came tumbling down as I luffed it –
lesson learnt, change the cable more regularly. At least no-one was underneath
it when it failed!
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