Re: [TowerTalk] misaligned vertical towers

[K8RI <K8RI-on-TowerTalk@tm.net>]

On 3/22/2013 1:55 PM, David Gilbert wrote:

Dave has a point.  Plumb bobs are rarely hung on a line over 5 or 6 feet 
long. They are too susceptible to air currents.
In all the years I've worked on towers I can count the days where it was 
calm enough to even use one on a 10' arm.
Use one about 5' long and sight along the line  Two at 90 degrees to the 
tower will give far more precision than is necessary.
The easiest and quickest is to use a laser transit or level.  Of course 
then the challenge is getting the measuring instrument properly set up
Typical big box stores laser levels and transits are good for about 
1/8th to 1/16" in 20 feet which is less than an inch on a 100' tower.
73,

Roger (K8RI)


> I truly do not see the quandary here.   You don't need a plumb bob
> hanging off the tower ... just hold a plumb bob out in front of you as
> high as you can hold it and line the string up with the towers one at a
> time from various vantage points.
>
> Dave   AB7E
>
>
>
> > -----Original Message-----
> > From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> > Steve
> > K7AWB
> > Sent: Thursday, March 21, 2013 3:00 PM
> > To:towertalk@contesting.com
> > Subject: [TowerTalk] misaligned vertical towers
> >
> >
> > I have two towers up.  A 90 foot Rohn 45 with a 6-el 20 meter beam on
> > it and
> > a 102 foot Rohn 25 without anything on it yet.  Both are guyed.  In
> > putting
> > them up, a group of us used a Loos tension meter and our eyesight at the
> > bottom of each tower to make them vertical.
> >
> > But when I look and align the two towers next to each other by walking
> > around until they are "next" to each other, one or both are off
> > vertically
> > with respect to each other.
> >
> > How do I figure which is straight and which is off or maybe both are
> > slight
> > off?
> > I really don't want to climb them now in the bad weather and drop a plumb
> > bob and do not have a survey level.  They are really 135 feet apart.
> >
> > 73
> > Steve Sala
> > K7AWB
> > DN17es
> > Nine Mile Falls, WA
> >
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