[TowerTalk] pushup mast source and other comments
Rob Atkinson, K5UJ
k5uj at hotmail.com
Tue Dec 28 20:38:03 EST 2004
Someone asked where to find Rohn 50 foot pushup masts.
If all else fails, try Majestic Communications, in Memphis TN.
http://www.majestic-comm.com/majesticcomm/rohn/index.htm
they have the H50 for $80.
Another correspondent writes:
<<<I am putting up a 40 foot mast for my GAP Titan and will be
using Probably 3/16 black Dacron rope and possibly guy grips unless I go
With rope to small to use with them.>>>
I hope you are not planning on putting a 25 pound 25 foot tall gap titan on
top of a 40 foot pushup mast. Firstly, that will be a heck of a job getting
that thing in the air; but more important, the gap will tear that mast up.
the gap needs a thicker wall steel pipe support; the typical galv.steel
pushup mast is not made to handle the weight and load and stress of such a
big antenna.
I advise anyone wanting to go up 40 feet with a pushup mast to spend the
extra 25 dollars and get the H50, and pull out the top section, throw it
away, and use the bottom four. The top is so skinny I do not think it is
secure except for holding up real small light broadcast rx antennas and
wires.
the three way guying is okay if you are an honest 120 deg. apart and each
section is guyed, and the anchors are at least 25 feet out for a 40' mast.
For a 1 year installation, go to a hardware store and get the painted 2 or 3
foot long earth screws that are about 5 bucks each (in the northern midwest,
Menards has them) and use dacron. Forget the clips and thimbles unless you
use wire but for a H50 that's overkill. Just tie the rope to the guy ring
using a bowline knot (see http://www.radioworks.com/ninstallant.html and
scroll down).
Get a bunch of cheap knockoff locking pliars for 3 to 5 bucks each (about
what a thimble and 3 clips would cost but don't get visegrips or you will go
broke) and pull the rope tight through the earth screw eye and clamp it with
the locking pliars. get the needlenose pliars as they can handle two ropes
each. These hold the rope fine and are a walk in the sun compared to
kneeling in the snow for a half hour with nut drivers, pliars, etc.
tightening clips.
The rope will stretch out a bit after a week--just pop the pliars off,
retension and put them back on. You will retension all your guys in a half
hour and be back inside drinking coffee, but this only works for a light
duty pole and dacron.
if you have to put all this up alone, it can be done: get out the mast and
extend it on the ground to make sure it is ready to go and does not bind
anywhere. mark out where the anchors are going and put them in and get a
post hole digger and dig a 3 to 5 foot hole where you want the pole. Drive
in a 8 foot metal fence post in the hole so it's in 2 or 3 feet into the
bottom of the hole, making sure it is vertical. dump in around 6" of
gravel, put the mast in and strap it to the post with hose clamps. guy off
the bottom section and make sure the mast is plumb. fill in the hole
with gravel. With it strapped and plumb and tightly guyed, you should be
able to push it up on a calm day and quickly guy it off with the pliars.
GL,
rob/k5uj
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