[Top] [All Lists]

Pushup pole questions

To: <>
Subject: Pushup pole questions
From: (Stan Griffiths)
Date: Tue, 17 Dec 1996 23:30:09 -0800 (PST)
>Hello towerphiles,
>I am going to be erecting a cushcraft 10-3cd on a 40 ft. pushup pole (extended
>only to 30ft.).  I will be guying it at 2 levels with 5/16 dacron, equally
>120 degrees apart. Two of the guy points will be to my house (eyebolts through
>the eaves at each end of the house - the position of the guys will be
pulling 'in'
>and 'up' over the eave), and the other guy point will be to a pole cemented
in the
>ground about 25 ft. from the mast.

I already have a coment.  Be sure to use eye bolts that are strong enough.
Hardware store eye bolts that are simply bent into shape are probably not
good enough.  They tend to come unbent under stress.  Forged eye bolts would
be best.

I have a question of my own, first.  Tell us about the "pole cemented in the
ground".  How high above ground will the guy be attached to the pole?  What
material and what are the dimensions of the pole?  Are you sure it won't
bend or rotate in the ground as the guy wire pulls on it?

>A few questions:
>1) Guy tensioning - One of the guy points will make for a fairly steep
guying angle.
>The other 2 guy points will be relatively shallow (I'm guessing about 25 deg.).
>I have no tensioning tool (yet).  Should the tension be fairly equal?

Assuming you have three guys attached to the same level on the mast and they
are coing down at various angles to the ground, there is no way you can
equalize the tension in the individual guy wires and still have a plumb
mast.  The steeper guy will have to have the most tension in it to hold the
mast plumb.  This is because the mast will move to seek a position such that
the horizontal forces applied to it by all the guy wires are equal.  I would
be careful not to get the steepest guy too tight and tighten the others to
make the mast plumb.

  How much
>stretch should I expect from 30-35 ft. of 5/16 dacron/poly?  Should I clamp,
>or just tie a big ugly knot?

I can't help you here.  I never use the stuff.

>2) Since I'm only going to use 30 of the 40 ft., which 10ft should I leave
>retracted... the top, or bottom? Which method would provide the best

I would be concerned about the mast bending so I would use the three largest
sections extended which are the bottom three.  I would leave the top section
retracted and I might leave it out totally.

>3) What should the bottom of the mast sit on? It cannot be anchored to
>the house, so what should I use to keep it from rotating?

I would proably set it on a 18" square of 3/4 inch plywood with some two by
fours  nailed to the plywood forming a square to keep the mast from moving
horizontally.  I guess you will have to put a pin through the bottom of the
mast and figure a way to keep it from moving to prevent rotation.

>4) Would it be safe to add an 11 el. 2m (or even a 4el end mount) a couple
>ft above the 10-3cd?

Probably, but you have not told us how big the top of the mast is, ie:
diameter and wall thickness.

>5)  Does this sound like a sturdy enough setup?  My qth is on a hill in a new
>subdivision with few trees to block the prevailing winds.  There is always
>at least a steady breeze blowing.

It sounds marginal to me, as do all small masts with an HF beam mounted on them.

>All hardware is new, btw.  And a new rotor will be mounted as well.
>I know this may come off sounding like a lot of worry for such a relatively
>project, but I want it to be as safe and trouble-free as possible.  And
when I'm
>in bed listening to the wind howl,  I don't want to worry about it (too much).
>Thanks for your help... rich

Hey, Rich, better to be safe than sorry and I bet you have heard that
before.  I am sure you will get some other opinions here.


FAQ on WWW:     
Administrative requests:
Sponsored by Akorn Access, Inc & KM9P

<Prev in Thread] Current Thread [Next in Thread>