[TowerTalk] Temporary guy anchors.

[Roger (K8RI) on TT]

For temporary guying, you "must" know the expected force on the anchor, 
both vertical and horizontal.
The taller the mast the higher the force, just as in the larger the 
antenna wind load the larger the force.  With guys, the lower the angle 
(farther the anchor is from the mast) the lower the vertical force, but 
the horizontal force goes up.

These forces can be easily figured using Trigonometry.  Forgot your trig 
functions? (I have to look them up every time)  You could purchase a 
trig book, but for a lot less money, they are available on the net with 
simple "insert the numbers" formulas that will do the work and you may 
not need to remember the specific trig function.

"That gives the forces, BUT you need to know what will hold those 
forces!   A big concrete block sounds good, maybe.  We would generally 
use one on an asphalt parking lot, but the holding force can go from 
great to nil on the same size block.  A little sand, or just a little 
gravel will turn that solid anchor into a useless block, you can easily 
push, so make sure the surface it sets on is absolutely clean as is the 
bottom surface of the block. Usually a block, heavy enough to be useful 
is too big to be easily handled by one or even two men. It takes a lot 
of force to start the block sliding, but much less to keep it moving.  
If the angle is too steep, the force will lift on the block, greatly 
reducing its resistance to sliding.  That is not a simple 
problem/calculation for most amateurs. It's in first year, calc based 
physics.

If you only go 30 to 40 feet with a small tower (25G), or mast topped 
with a small to modest sized tribander, or UHF/VHF antennas, the screw 
in anchors like the ones for temporary tied-owns for aircraft will 
usually work quite well in solid soil. By solid soil, I mean the type 
that you need to use a 2 or 3' long pipe through the top of the anchors 
to make the last two turns. Do not lean the anchor to be in line with 
the guy line. Screw it in vertically. These are typically made of 3/8ths 
or 1/2" steel rod.  Don't settle for the little ones made of 1/4" rod. 
You can drive a 3' Welded "T" into the ground with a 1 or 2 ft  "T" on 
top. The longer T is to help twist and pull the rod to remove it. The 
Welded "T" needs to be at least twice to 3 times the length of the 
screw-in anchor.  It helps to use at least a half inch rod, although 1" 
is better.  1" stands up well to being driven in with a 10, or 12# 
sledge hammer. Harder to get out too<:-)  1/2" bends too easy.  BTW that 
weld needs to be a good one that won't fail with the first blow from the 
sledge hammer.  A straight rod driven in far enough to be a useful guy 
anchor is likely going to take work to remove.  It can be driven in at 
an angle, 90 degrees to the top guy

PS:  Don't forget to grind a point on the end of the rod.  It really 
helps with a 1" steel rod.  BTW, a 3', 1" steel rod with a 2", 1" steel 
rod welded on top is surprisingly heavy!

An added note: you can use trailer hitches on pickups, or SUVs.  2 
important things to remember park the SUVs or Pickups far enough away 
from the tower that they can not be hit be the tower, or antennas if a 
guy fails.  Additionally: Place the SUV, or truck and set the brake 
BEFORE attaching the guy.  I've seen the local club use a tower base 
with a steel plate extension, that they parked a car or truck with a 
tire on the plate to hold the tower base in a parking lot.

  73

  Roger (K8RI)

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