Is there any way to _calculate_ proper number and heigth of guying
for such "Texas Tower" telescope?
I am going to build a 55' tall field-day style vertical for 160-80-40m.
The vertical gonna consist of 11 six-feet sections - it gonna be either:
- all 11 of them from 2" to 3/4 made of 6063 with 0.058" walls
- 10 of them from 1 3/4 to 5/8 of 6063 + 2" section with walls 0.125"
thick made of 6061, like Hy-Gain sells.
it is not suppose to stand in the backyard for all year around... the
purpose is to go to some vacation rental, set it up using one
man-hour, operate in a contest and go home.
i want it to last reasonably long, but surely dont want to have any
overkill like 3" pipes on concrete base with 5 levels of guy wires :)
Alex K2BB
> From: "Tom McAlee" <tom@klient.com>
> To: <towertalk@contesting.com>
> Subject: Re: [TowerTalk] 80m vertical: reality check
> Date: Sat, 28 Oct 2006 16:06:06 -0400
> List-post: <mailto:towertalk@contesting.com>
>
> I have 2 full-size 80m verticals using tubing from Texas Towers. The
> current versions have been up for 1.5 years with no problems. But, they are
> the third version. The first 2 attempts didn't go so well!
>
> As they are now, they start at 2.125" and telescope to 1.25". They are 6'
> sections with several of the first 3 sizes doubled up. They are guyed at 5
> levels (every 12') with Phyllistran to posts 43' out, guys attached to the
> top of the posts that extend 3' out of the ground (makes mowing the yard
> easier)
>
> These verticals cannot be "walked up" as you would do with a smaller
> vertical. I used a 60' bucket truck to build them 12' at a time. I found a
> local sign company that charges $55/hour and it took about 1/2 hour per
> vertical.
>
> Mistakes made in the first two versions that were destroyed on windy days:
> - telescoping up to too small a size that couldn't withstand the vibration
> in the wind and broke off
> - not having enough guy levels (without enough of them, you can't tighten
> them much because tightening them will buckle the tubing without more guys
> below to prevent that)
> - not having the guys out far enough (tried to be cheap on the Phyllistran,
> bad idea)
>
> 73,
> Tom, NI1N
>
> ----- Original Message ----- >
> From: towertalk-bounces@contesting.com on behalf of Yo3ctk
> > Sent: Fri 27/10/2006 12:40
> > To: towertalk@contesting.com
> > Subject: [TowerTalk] 80m vertical: reality check
> >
> >
> >
> > I am trying to design an 80m lambda/4 vertical for a 4-square. My plan is
> > to use 6 ft sections of AL tubing, 0.058" wall, as advertised on Texas
> > Tower website:
> > http://www.texastowers.com/aluminum.htm
> >
> > Starting with biggest O.D of 2.125", twelve (12) more 6 ft sections of
> > progressively smaller O.D. will be telescoping with 1 ft overlap at each
> > joint. Joints will be fastened with AL rivets. The entire vertical will
> > have an (adjustable) height of 66 ft (20m) and a total weight of about 22
> > pounds (10 kg).
> >
> > Unfortunately I have no expertise in calculating if such a structure is
> > mechanically sound, hence following questions for the experts on the list:
> >
> > 1. Is the vertical expected to break at the lower joints in stiff winds
> > (say no more than 65mi/100km/h)?
> > 2. Must the vertical be guyed? Where?
> > 3. Is it feasible to raise the vertical from the ground, by fixing the
> > largest section to the base and telescoping sections starting with the
> > smallest diameter, and riveting as we go?
> >
> > Thank you all for any comment.
> >
> > 73 de Mike, YO3CTK
> > YR7M stationmaster
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