Hi Steve,
The best way to check tower vertical aligment is with
a surveyer's transit level that is properly set up.
Another way is to hold up a plumb bob with a string,
arm extended. (Yeah, it's hard to hold it steady, but
maybe there's something you could use to hold the
string-bob steady.) Sight along the string to the tower.
Once "straight on" and then take the next sighting at 90 degrees
from that. It will be quite obvious which tower (or both) is grossly
not vertical, out of alignment, etc.
Again, the best way is with a transit and you'll be
able to check deviation right down to a fraction of an
inch with the telescopic sight and cross-hairs.
Don't have one? Get one, even if it's a class of level called a
"Dumpy Level". Also, you'll need a sturdy tripod.
BTW, the formula for maximum allowable deviation between guy points is
h/360 *or* W/20, whichever is less. h=length between guys on a tower,
W=the width across the face of a tower section.
The maximum overall deviation (of the entire tower), and true vertical,
bottom to top is H/360. H=total height of the tower.
Ref: Bell System Practices, Outside Plant Engineering, addendum
AG25.300 Issue 2. "Maintenance of Antenna Supporting Structures".
The Reference states that the W/20 formula doesn't apply to "System
Standard Towers" (I'm *guessing* the "Standard Towers" are towers that
are
generally self supporting and tapered.)
About tensioning...Equal tensioning does NOT guarantee a vertical or
perfectly
aligned tower!!!
73,
Charlie, N0TT
On Thu, 21 Mar 2013 13:00:27 -0700 "Steve K7AWB" <k7awbgoog@gmail.com>
writes:
>
> 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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