Hello Rudy,
Here's a simple and elegant method:
1. Use irrigation drain tubing to make a form for a sack-Crete base. Insert a
12" G10FR4 rod 4 inches deep into the center of the concrete pad and let it
cure. this g10 rod is machined to an OD that tightly fits into the ID of the
bottom aluminum member of the vertical.
2. Build the vertical elements starting at 2" x .125 wall x 24ft. Double bolt
the g10 6" into the bottom 2" member. That leaves you a 2" gap between the
concrete and the radiator.
3. Step down the 1.75 ID OF THE 2" OD member using an machined reducer that has
been machined to accept 1.25 OD aluminum. Telescope from 1.25 to 0.5 to obtain
your final needed length.
4. at the 2" to 1.25" articulation there is essentially a shelf. Use 3/8"
aluminum plate to make a simple guy adapter. Guy using phillystran to stakes.
5. You can make a second and third guy point higher on the vertical if desired.
6. Rent a man lift or bucket truck to install. Trying to upright this unit
using the Armstrong method would be dangerous.
7. As always take all safety precautions!!! Especially DO NOT INSTALL ANYWHERE
NEAR ELECTRIC UTILITY WIRES!!! Also make sure that the man lift operator
follows all safety precautions especially including setting the machine on good
footing and never working on windy days.
Best regards,
Scott w3tx
On Oct 13, 2012, at 6:35 PM, Rudy Bakalov <r_bakalov@yahoo.com> wrote:
Dave,
Your Rohn-25 verticals are indeed impressive, but unfortunately beyond my own
capability to build unless I hire a tower crew. Ditto for making my own
aluminum tower.
You reminded me that the other consideration is, if possible, to avoid guy
wires. And yes, I am considering using 24' sections to make the construction
even easier. I guess the design boils down to what size taper I should use. I
am also wondering how I am going to erect these 68' beasts, but my neighbors
have any and all earthmoving piece of equipment known to mankind so I am sure
we can figure it out.
Rudy N2WQ
________________________________
From: K1TTT <K1TTT@ARRL.NET>
To: 'Rudy Bakalov' <r_bakalov@yahoo.com>
Sent: Saturday, October 13, 2012 6:24 PM
Subject: RE: [TowerTalk] Choice of aluminum
My material of choice was rohn-25... you might ask k1ea what he used, he
made free standing 80m verticals. T6 vs t8 - you probably won't notice the
difference unless you had them side by side and were machining them. the t8
is a bit harder but has less shear strength. There are also very comparable
6063 versions if you can't find 6061 for some reason. I would go with .125
or maybe even .25 for the bottom section or two probably, but I'll bet there
is a design program out there that someone can provide that would give more
specific requirements. 12' has other advantages, like lots less joints!
20-24' would be even better, I know some tubing is available up to 20' at
least.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net
-----Original Message-----
From: Rudy Bakalov [mailto:r_bakalov@yahoo.com]
Sent: Saturday, October 13, 2012 21:09
To: towertalk@contesting.com
Subject: [TowerTalk] Choice of aluminum
I was wondering if anyone can help me select the right material for
full-size 80m verticals. My questions are as follows:
1) metalsupermarkets.com offers 6061-T6 aluminum, but not T8. Is there a
difference between T6 and T8 for my purpose?
2) Should go for the 0.125 or 0.065 wall thickness?
3) Is 1" tubing OK for the topmost segment? Too stiff for the wind at 70'?
Not strong enough?
I am aware that many ham stores offer 6061-T8 tubing, but I do want to buy
it local in VE3, close to my QTH, in 12' lengths (instead of 6') and avoid
shipping complications due to length or clearing customs.
73 Rudy N2WQ
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