Darfug@aol.com wrote:
>Im taking down a 75ft rhon self supported tower.Dont know how old it
>is.Thinking of temperary guy wire to take down at least halve of the
tower.Just for
>feeling secure.Any ideas?It looks solid and very heavy duty.dar
Dar:
Taking down a tower is far more risky...make that dangerous
than putting one up. Considerable planning and caution is in order.
If you've never done it...you might want to leave it to people who have,
and are equipped to do it.
Saying it looks solid, based on ground level inspection,
is not adequate. You need to climb it and inspect carefully.
You also need to know how the sections come apart...and what
tools you will need to make that happen.
It may be quite solid...and solidly rusted/corroded together at the
joints, such that it won't easily come apart. Or, maybe not...
perhaps the joints were greased when assembled.
Without knowing the tower type specifically, it's
hard to give specific advice. The height, 75', seems
to rule out some types, unless that's approximate.
What is the length of each section? Does the tower taper,
or is it uniform cross-section going up? Size of tower
face, center-to-center on legs?
Are the tower legs tubular, with welded cross braces?
Is the brace pattern both horizontal and diagonal, or
horizontal only. Braces welded to tubes?
Or...is the tower made up of sheet material bolted together?
HBX type, for example, has formed legs made from sheet steel,
with bolted X braces.
What is the site like? Do you have clear access? A clear
fall radius? Nearby buildings or other structures? Any other
risks?
In my experience, which is far from professional, used towers
in the air are worth very little. Used tower sections on the
ground have fair market value based on their physical condition.
What's the difference? See what a crane will cost for a half
day, to safely take it down...then value your time to disassemble the thing,
once it's down. Compare that to what it'd cost you to simply buy
something ready to go...or new.
If you don't have a ginpole and tower jack, plus a minimum of 200'
of working line....you're not equipped to take the thing down. By
the time you acquire that stuff, you'd be better off just buying a
tower. There is probably as much invested in the foundation of a
self supporter, as there is in the air, so it may not be a bargain,
in any case.
An example of what can go wrong:
I bought a 100' rohn 25G in the Pocono mountains, some
years ago. Paid 25 bucks a section for it..in the air. A couple of
yagis came with it, as did a rotor...I think I paid $500, total.
Turned out, it was guyed with plastic coated .125" aircraft cable,
and didn't feel solid, when topside.
Turned out, the wind always blew at 30kts at 1800' asl. We went to
the site 4 times, hoping for reduced wind.
It cost 30 bucks in gas every time I went to the site.
We got the beams off and down in a day, but I tore my left shoulder,
wrestling the 20m 4 el onto the tram line, in the 30kt wind.
After struggling to get other experienced tower crew, I gave up.
We attached one set of guys to a pickup truck, cut one leg, and pulled
the tower over, letting it land in a flat spot...undamaged.
The truck acted as a brake, slowing the drop considerably,
as it was dragged 100' on locked wheels.
Total cost: 500 for tower, 240 for gas, $100 for crew meals, $1500 for
physical therapy on my shoulder(which still hurts, 20 years later),
and over 60 hours labor and transit time.
But I was doing a favor for a fellow club member's family, and we got it
down.
Later, some idiot told them that the stuff was worth far more than I paid
for it,
and suggested that I'd robbed them. The difference, of course, was the
value of the take-down.
My advice: Don't risk life and limb unnecessarily. There ARE no free
towers.
N2EA
jimjarvis@ieee.org
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|