|Subject:||Re: [TowerTalk] Tower costs|
|Date:||Tue, 24 Aug 2004 23:43:22 +0000|
NV8A asked after W4ZW described his roof tower installation:|
How do you (generic "you") know what loads your roof will stand? How can you be sure that a good strong wind -- 60mph, 80mph -- won't take the antenna and the tower and a section of roof -- or the whole roof -- with it?
Only one station went to any effort on the engineering side of things, in order to satisfy the building management.
Otherwise, what we all rely upon is taking the antenna down in advance of
inclement weather. The rule of thumb is 70 knots - I have one of those poxy
JA aluminum erector set bolt-together towers that is 6m tall, always uses a
gravity base & is guyed with Kevlar halyard into the roof parapet walls - now on
it's fourth, three story house.
These houses may be reinforced concrete, but are exempt from any building
regulations. Some may have poured walls, some might not have a single load
bearing wall & everything is bricked in between the columns. Some are slapped
together so quickly that the balconies fall off them. They all leak within a decade
of construction - not exactly what one would expect of a non-third world place
like Hong Kong.
I doubt we could do any valid calculations to satisfy anyone & we are obliged under license conditions to install antennas with "good engineering practice". It may be a pain, but taking the antenna down is the only way we can make it work.
73, HL1/VR2BrettGraham (watching a typhoon veer towards HK that luckily should have dissipated enough, as I didn't take the antenna down before leaving ;^)
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.
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