In a message dated 96-02-07 23:22:43 EST, you write:
>I am in seriously contemplating putting up a tower here at my QTH in
>Florida, and was wondering were I could get information on how to make wind
>survival versus tower size tradeoffs, guy selection, etc. I am considering a
>60 to 70 foot guyed tower with a something like a Force-12 C-3 Tribander
>stacked under a Cushcraft 402CD. Being in Hurricane country, I would like to
>be able to do wind survival comparisons between Rohn 25, 45 and 55 to see if
>the heavier tower sections are worth the added expense.
Hello, Michael,
Yikes, what a challenge! According to my Atlas, you are in Brevard County
which is a 105 MPH TIA-222-E wind zone. The first thing you have to do is
get the Rohn catalog. The consumer products catalog has EVERYTHING up to 55G
including drawings and specs for 110 MPH installations. If you follow their
specifications and build it for 110 MPH, there is virtually no problem with
the tower withstanding those winds. BTW, 100 feet of 25G will take 7.4
sq.ft., 45G will take 7.9 sq.ft. and the 55G will take 15 sq.ft.at 110 MPH.
That's pretty interesting in itself. The catalog can be obtained through
most Rohn dealers or direct (309-697-4400, ask for Dana Lemmerman.)
Antennas are another story. Physically robust antennas such as the TH7DX
are rated from the factory at 100 MPH. The decision is "do I put up
something strong enough (and expensive) or do I put up anything and let it
blow apart and replace it periodically?" Either way, your homeowners
insurance should cover it as personal property (you may need an additional
rider.) A local ham has a "Big Bertha" that was designed to withstand 150
MPH winds at which point the antennas would "shed" off the tower.
Masts are pretty well documented so the crux decision would probably be
antennas. Cushcraft's are not physically strong at all (you get what you pay
for.) I'd probably get something suitable to begin with knowing that you may
be making changes in the future!
I have extensive experience in amateur and commercial tower construction
and would be happy to provide you with my experiences. Give me a call if
interested (206-485-7913). Good luck!
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