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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