There *is* no such thing as simple trig, if your last brush with a
cosine was 56 years ago! Fortunately, you can back this one out with
the old hypotenuse formula. Even I remember how to do that.
73, Pete N4ZR
The Reverse Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000
On 11/1/2012 3:35 AM, K8RI wrote:
On 10/31/2012 11:00 PM, Hans Hammarquist wrote:
I was wondering if someone has experience with a 43 foot vertical,
mounted on top of a
tower. I used one before on top of my roof, but that one was
supported with simple guy wires.
Needless to say that is not easy to do if I put it on top of my
tower (85 feet tall).
Any suggestion? Maybe it is a very stupid idea?
Guying at 80 feet is almost as simple as guying when on the roof. I
assume the tower is solid so use the same anchor points on the
vertical as you would on the roof. It's just the ground guy anchor
points have to be farther out.
It only takes some simple trig to calculate the length of the guys
assuming the yard is farily close to level. Use single or doubly
braid poly. 1/8" is strong enough to anchor about 3/4 the way up the
antenna.
If the tower is 80 feet and the antenna is 43 then 2/3rds of 43 is
roughly 28.6 feet (give or take a foot or two) So the height is 80 +
28.8 is 108 feet. If the distance from the tower to the guy anchor
is 80 feet then sqrt(108^2 + 80^2) and I don't have a calculator in
there to run that last square root.
I'd use double braided poly on the vertical and probably Phyllistran
on the tower. However I think the 43 foot vertical is going to need
radials so I'd use steel for those. I've done that with a 40 tower
and 33 foot vertical and it worked just fine. I only used 4 radials
but was pleased with the results. Course that was back in the late
60's until about 1980.
73
Roger (K8RI)
Hans - N2JFS
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