You are to be commended for sharing your experiences and I
agree with your philosophy. A lot don't share their
experiences because they get chastised by people who throw
around words like 'unsafe'. Have these people ever heard of
'risk analysis'? Really...how much will your tower
withstand can only be determined by 'product testing to
destruction'. If your tower arrangement has survived for 25
years then IMO you have a safe installation. Great job!
Doug/VA5DX
Subject: Re: [TowerTalk] Mast wind loading
> Hi All,
I have been biting my tongue for years about the
theoretical load of Rohn
towers. It may be important for building code purposes and
surely is for
Rohn's litigation exposure, but in the real world it is
really unimportant.
A properly installed and guyed Rohn tower will hold MANY
times more than
indicated in the catalogs. I look at the pictures of Rohn
25 with a single
beam at the top because of "loading' and I laugh. Here in
the Northeast
there are dozens, if not hundreds of big contesters with
super-loaded towers
for years without any mishaps, except for the ocassional 2
inches of ice and
50 mph winds together. My 100 foot Rohn 45 tower has a 15
foot, 3 inch moly
mast with a 4 element homebrew 15 meter beam on a 35 foot
boom and a 4
element homebrew 20 meter beam on a 57 foot 3 inch boom.
At 80 feet I have
a 2 element Cushcraft 40 meter beam, at 68 feet I have a
TH7DXX, at 50 feet
I have a homebrew 6 element 10 meter beam on a 27 foot boom,
and 34 feet I
have another TH7DXX, and at 70 feet I have a Ringo Ranger II
vertical. You
calculate the wind loading!! It's been up for over 25 years
without any
problems. So, If you need official documentation, follow the
catalog values.
If you want to put up real antennas, just do it, but do it
right, no corner
cutting or compromises in materials. Just my opinion.
Perhaps you should have continued biting your tongue.
The aforementioned
anecdotal observations are interesting but have no basis in
fact or
engineering practice. Sure, hams overload towers and, sure,
most of them stay up but
that doesn't mean that they are safe and reliable
installations.
Ignore the LXC Prime Directive to "DO what the
manufacturer says" at
your potential peril.
Cheers,
Steve K7LXC
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.3.3/295 - Release
Date: 3/28/2006
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|