Hi Bob,
Please don't take this comment too hard, but your questions all strike me as
the kind that should have answers before the first purchase is made and the
ground broken. Getting information in dribs and drabs as the project
proceeds is a great way to find yourself halfway done and realizing you need
a few more parts. Which isn't a disaster when everything's on the ground,
but if you're 40 feet up and wondering what to attach the first set of
permanent guys to, can be problematic.
Be that as it may: I think the answer to your levelling question is that no,
a plumb bob or spirit level will not suffice. You need the entire tower to
be as plumb as can be, not just the base. From 80 feet, the probability of
wind affecting the plumb bob is pretty high.
At 80 feet, you're going to use at least two guying levels. While the spirit
level is OK for making sure the first section is reasonably plumb, you're
going to need a transit for adjusting the guys to keep the upper parts of
the tower plumb.
I'd also look hard at K3LR's suggestion of a pier pin.
I'd also do a Google search to see if I couldn't find a comprehensive guide
to installing guyed towers. Some of the things you may be overlooking:
1. proper guy stations that distribute the force of the guying across the
entire cross-section of tower (some just loop a thimble over a brace, but
the weld isn't designed for that kind of stress); 2. EHS or phillystran
guys; 3. Insulators if using EHS. 3.5: EHS for the top and bottom portions
if using Phillystran (Phillystran has high tensile strength, but can shatter
if struck by a falling tool or vandals); 4. Concrete for guy anchors; 5.
Equalization plates for the lower ends of the guys; 6. Turbuckles; 7.
Tension gauge (to properly tension the guys). 8. Preform grips for the guys
(highly recommended if using EHS, proper terminations mandatory for
phillystran.) 9. EHS for temporary guys. There's probably stuff I'm
forgetting, as well.
Also, consider now how the antenna will be raised once the tower is up. Will
you tram it over the guys or try to manoeuvre it up through the guys? If you
plan on tramming, you also need to plan the backstay.
I would strongly suggest that before you place the first order for concrete,
you plan the installation down to the letter. Know that you have everything
you need on hand and plan out the course of events.
73
Kelly
Ve4xt
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of AD5VJ Bob
Sent: December-30-07 9:31 AM
To: k1ttt@arrl.net; towertalk@contesting.com
Subject: Re: [TowerTalk] Tower Update
Hi David and all:
Thanks for the information I was not aware of that, but am now.
I will make some phone calls and see what I can get done on delivery.
I guess another question would be, since I was thinking of leveling it with
a bubble level, but I dont have one that is over around
a 6" long. Will a plumb bob through the center of the first section be
accurate enough to make the tower straight as I go up in
height to say 80 feet or so?
I was rethinking the vertical leveling and thought I might just tie a string
at the center of the top of the section (ten foot
bottom section) I am going to cement in -
tie a rock or something to it
eyeball it to be in the center of the section
at the end of the string at ground level
then cement it in
But then remembered the higher I go
the more off center it will get if I am off at all at the bottom.
So would a three or four foot bubble level be the way to go instead?
Or would the plumb bob be accurate enough?
Bob AD5VJ
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of David
> Robbins K1TTT
> Sent: Sunday, December 30, 2007 9:03 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Tower Update
>
> That is the real reason to get concrete delivered... rohn
> specs call for 3000# mix, this is easy if you tell the
> company that is what you need. They will have a standard mix
> that will give you the required strength. Hand mixing I
> wouldn't trust to be able to duplicate that, or to be
> consistent throughout the pour.
>
>
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>
>
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com [mailto:towertalk-
> > bounces@contesting.com] On Behalf Of AD5VJ Bob
> > Sent: Sunday, December 30, 2007 14:50
> > To: towertalk@contesting.com
> > Subject: Re: [TowerTalk] Tower Update
> >
> > Thanks guys for all the answers.
> >
> > I sent a similar email to my local contest group (NTCC) and
> they are
> > coming back with very much the same answers you guys are as
> well. So
> > there is allot of confirmation to what everyone is saying.
> >
> > Looks like its nix on the inside box, just put her in the
> ground and
> > make the top attractive.
> >
> > Looks like around 60 bags of concrete (just a *little* off
> of my guess
> > of
> > 10) would give me the 10% over that many of the
> experienced guys are
> > talking about.
> >
> > Now I am not sure where to rent a cement mixer.
> > I will make some phone calls today.
> >
> > Everyone is telling me that I really dont want to mix the
> cement one
> > bag at a time.
> > Especially not 60 or so - 80 lb bags.
> >
> > One guy locally said after you get the bags of cement
> stacked at the
> > tower location that it seems to be some law of physics that
> the weight
> > of the bags at the top seems to drain into the bags at the bottom
> > especially over night Hi Hi Hi so I might want to have some
> other way
> > to do this rather than one bag at a time by myself.
> >
> > Which brings up another good question, what kind of
> concrete do I get,
> > I just found out from a reply that there is more than one kind of
> > concrete.
> >
> > Someone just told me there are different mixes and
> therefore different
> > hardness's to concrete mix.
> >
> > What kind of concrete do we buy for our tower purposes in
> Ham Radio?
> >
> > Tnx Bob AD5VJ
> >
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> _______________________________________________
>
>
>
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