You will probably be okay at 75 to 80 feet with standard guy tension and
modest antenna (<10 sq feet). The only problem would be an extremely high
wind (70-90 mph) from east or west against the widest spacing. To view guy
details, visit the Rohn web site:
http://www.rohnnet.com/ROHNNET/rohnnet2004/html2004/index.html
Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Cliff
Sent: Wednesday, December 08, 2004 5:12 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Tower anchor placement question.
Hi all,
I'm in the process of putting up a Rohn 25 tower, but have some concerns
about placement of the anchors. I would like to have some qualified opinions
on this layout. There are a number of reasons that led to where I have
placed my tower, which I'll not bore everyone with, but instead I'll
describe the placement.
The tower height is not exactly set, but will be a maximum of 95 feet above
ground, including a tapered top section. It may be one or two sections
shorter, depending on how tall the forest around me really is
(can't exactly determine from ground level.) The terrain is a ridge
with the tower placed near the ridgeline. The tower base is a full
straight section set in 4'6" of concrete (with 6" of gravel below for
drainage of the tower legs that stick out the bottom of the concrete.)
My questions center around the placement of the guy anchors. I am
using AB Chance 816 anchors - 66" long, 8" diameter auger, 1" shaft, 12,000
lbs pull strength in local soil, so they should be adequate.
There are to be 3 guys at 3 different levels. At present, I am planning
for 31', 63' and 90'. The 31' is necessary for one set of wires to
clear the roof of my house.
Anchor #1 is placed at 180 degrees, 79.5 ft from tower and 56 inches above
tower base height.
Anchor #2 is placed at 300 degrees, 90 ft. from tower and 52 inches below
tower base height.
Anchor #3 is placed at 60 degrees, 52.33 ft from tower and 7 inches below
tower base height.
This seems to be the optimum placement for the terrain. #1 is placed in the
front yard forest, and is movable. #2 is placed to allow sufficient
clearance to drive a vehicle under the lowest guy wire.
Here's the real question. Anchor #3 is placed as close to the property line
as possible, but only 52.33 feet from the tower. This distance is only
about 55% of the height of the top guy wire. What is the opinion
of the knowledgeable on this location? Can/should I compensate for
this by varying guy wire tension around the tower? Any other suggestions?
I do have a tension gage to use on the 3/16" EHS guy wire that I am using.
73,
Cliff, AG4XR
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
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