[TowerTalk] Climbing crank-ups & guy points

[Peter Chadwick]

Adding to what Mike said:
My UK made crank up/ fold over is rated by the manufacturer for 9.9 square feet of antennas at 120mph when guyed. It is rated for 70mph with 9.2 square feet when not guyed. It's carrying a T2X rotator and a 4 ele Steppir at 62 feet now - it was loaded up with a 205BA at 62 feet and a 4ele for 15 interlaced with a 4 ele for 10 at 68 feet. It stays up except dor maintenance and the occasional predicted very high winds, although it was up in the storms of 1987 and 1992, both of which hit 120mph. When I have time, there's a very big heavy electric winch to go on it to save the trouble of hand winding. When I last looked, the manufacturer's electric winch  was over $1100 - and that's a good ten tears ago.
Interestingly, the concrete base called for is 5.5 by 5.5 feet by 4 feet deep, with no rebar. The tower has a  base mount that folds the tower (retracted, of course!) over from about 6 feet up, and  the whole lot weighs 1160 lbs, so when folded over, there's a fair bit of tension on the concrete, but apparently, not enough to worry about. The bolts holding the base plate in the concrete are 24mm diameter, about 24 inches long, with 3 inch square wash plates on them: this sort of installation is probably reasonably typical for those UK hams who have towers. Having said that, a number of people use a ground post to hold the tower, rather than a bigger base plate approach. I went for the base plate because it's easier to get a flat level concrete surface than a 6 inch diameter steel post exactly upright in the concrete!
At today's prices and exchange rate, it's also around the $5k mark, over rather than under, I suspect.....it's been up 20 years this month. (Suddenly realised that with inflation, it might be underinsured - need to look into that). I've changed the wire ropes once, not because they needed it, but they looked like they might. Similarly, the guys, which are prestretched UV resistant polyester rated for a breaking strain of 4000lbs. New ropes of this quality cost about $600, plus the effort in splicing the thimbles in. (I use Marlow brand marine ropes - they are well prized apparently in US yachting circles) When up, the first section sits on a hefty catch. Climbing has only been done in an emergency and then with lengths of 1 inch diameter BMS bar inserted so that each section is sitting on the BMS, not on a rope. (It needs about 10 tons to shear that much BMS) I use a spray wire rope dressing from Rocol, and touch up the galvanising when needed with spray on cold galvanising spray - not brilliant, but better than nothing.
I guess there's a lot of difference here between UK and US practice, while at today's prices the conccrete base alone would be the best part of $750. All in all, doing a tower installation isn't likely to be cheap, crank up or fixed.

73 es HNY
Peter G3RZP