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Yep... I agree! I use a 24' piece of STRUCTURAL 6061-T6 (1/4" wall thickness,
2.5" OD) aluminum tubing for a mast and it has stood up to some god awful
stress... a LM KT34-XA, a quad (4) array of 2 mtr. horiz. (24' booms), a pair of
440 Mhz horiz. (15' booms) inside the 2M quad array, and a 12' vertical 144/440
Mhz on top! Been in some tornado winds and mine stood vertical (some damage to
antennas... none to mast) and many, many friends in area lost HIGH strength
steel masts with LESS wind loading and NOT as tall with recorded tornado winds
less than what was recorded near my QTH!
If your antenna/tower supplier does not have structural aluminum tubing...
contact a national outfit that goes by the name: Tube Sales (many, many
locations around USA and wholesale only but you can generally talk 'em into
selling you a standard 'stick' - 24'... they will NOT cut it or haul it for
small quantities... truck load, only.)
Pound for pound, etc., this structural grade (expensive $200 +) 'stick' is many,
many times stronger than steel! Also, to approach the capabilities of this
material, steel would be many times heavier and will bend to crimp/crease
easier... NO flex! Without flex, something gotta give!
I cannot imagine the weight of a 24' piece of steel in the air, on top of my
tower, with all the wind loading, that would weigh as much as it does. Scary!
d.dimitry wrote:
> Dear Mr. Hider and friends,
>
> I beg to differ with the opinion you expressed. It is not uncommon for my
> office to hear from many hams (yes, customers) who have had their aluminum
> towers up for well over 20 years, some even approaching 40 years. Crank-ups
> have an especially high survival rate, even in hurricanes, etc. It's not
> surprising to hear these testimonials anymore; that's how the towers were
> designed.
>
> Needless to say, most of these guys have aluminum masts with the towers. I
> think it is true that some aluminum masts are on the light side. However,
> several years ago we started offering HAMS heavier walled material. No
> doubt, many chrome-moly masts would still have a greater yield strength.
> The question is: Is it necessary, and are you willing to pay the extra
> change? Consider also, that you may be paying more for a nearly invincible
> mast, only to have your antenna torn to shreds in serious winds.
>
> Aluminum towers in general have stood the test of time. In addition to
> their strength, they offer the corrosion resistance and light-weight, that
> some owners both want and need. No one can reasonably argue that they fill
> a niche, but even that is a large understatement. One last comment: like in
> anything else, compare apples to apples. There are different manufacturers
> of aluminum towers, just as there are different car manufacturers,
> everything from Chevies to Cadillacs. Do your homework.
>
> I would be happy to provide thorough calculations to any interested HAMs
> about contemporary designs that meet strict up-to-date engineering codes.
>
> Drake Dimitry
> DDimitry@HeightsTowers.com
>
> You wrote:>
> >I can't help with ques #1, but for question #2> Throwaway the aluminum
> >mast. Don't use it. The only aluminum on a tower should be the
> >antennas and associated mounting plates but, no masts. Especially such a
> >l o n g one. Long masts need strength and aluminum can't hack it, even
> >6061-T6. Get yourself a 24 ft chromally mast. You ought to see my
> >118,000# yield strength, 18 ft chromolly mast, bearing at 134 ft, with
> >25 sqft of antenna moves in the 60-70 mph winds we get twice/year. Then
> >answer your question mathematically. Don't even think about aluminum.
> >Many many horror stories can be re-told about such masts. There will be
> >others on this reflector who will tell you how long their aluminum masts
> >have been up. Others will tell you how long their aluminum towers have
> >been up. I for one need to be able to sleep at night. (I even have
> >galvanized steel inserts in the aluminum booms of some of my antennas!
> >So do some of my friends!!)
> >
> >Visit my web site: http://www.erols.com/n3rr
> >
> >Bill, N3RR
> >
> >donald.s.tucker@exgate.tek.com wrote:
> >>
> >> Hi,
> >>
> >> Just subscribed and seeking some help.
> >>
> >> Question 1. I have acquired a like new Triex T-51 3-section motor driven
> >> crankup. I built the base and poured the cement according to Tri-ex
> >> instructions and even made it a little deeper and wider, both ways. I
> >> included and installed in the base a 20 foot 4x4 steel tube which I had
> and
> >> will use it as the tilt-over support and a wire antenna leg. What I am
> >> looking for is a 2-way locking hand winch that I can use to tilt the
> tower
> >> over on its hinge and pull back up knowing that I am doing so without the
> >> possibility of losing everything. All I can find is a 1-way hand winch
> such
> >> as used for boat trailers. Would appreciate any suggestions or pointers
> as
> >> to where I can locate such an animal or a work-around and the size and
> >> strength of steel cable to use.
> >>
> >> Question 2. I have a 2 inch 6061-T6 1/4 wall 24 foot piece of tubing
> which
> >> I acquired to use as a mast in the above tower. Want to mount my TH7DXX,
> my
> >> KLM 40M monopole, and a 12 ele 2M beam. My intention was to place a plate
> >> with a bearing where the original rotator goes, and put a new rotator
> plate
> >> further down the tower, to take any stress off the rotator. My concern
> is
> >> how much mast I could (should) leave out with the antennas noted and if I
>
> >> could sneak in a small 12/17M beam.
> >>
> >> Don W7WLL
> >>
> >> --
> >> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> >> Submissions: towertalk@contesting.com
> >> Administrative requests: towertalk-REQUEST@contesting.com
> >> Problems: owner-towertalk@contesting.com
> >> Search: http://www.contesting.com/km9p/search.htm
> >
> >--
> >FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> >Submissions: towertalk@contesting.com
> >Administrative requests: towertalk-REQUEST@contesting.com
> >Problems: owner-towertalk@contesting.com
> >Search: http://www.contesting.com/km9p/search.htm
> >
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
> Search: http://www.contesting.com/km9p/search.htm
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