[TowerTalk] Re: Tower Base Hole?

[Bob Smith]

HI All,

Well , up to this point i've got you all beat on the hole situation.  I Dug 
my own
hole for the base of my LM-470D in 1984.  The spec said 3.5' x 3.5' x 
7'6".  Well
I'm 6'3" tall and I knew that I wouldn't fit in the hole while digging 
it.  So I figured
a 4.5 sq size would be better to work in and there were NO regulations for 
installation
of the tower in my 'city', I checked and got a letter from the city manager 
saying that
the regulations DIDN'T exist and a permit was needed.  (much to his 
amazement after
I installed the tower and antennas)

Well the ground was a little soft and I finished up with a hole about 5 x 5 
x 8.  A couple
of days later I found that there was a 'small underground stream' at the 
bottom and
the hole had grown to about 6'x 6' at the bottom after we pumped the water 
out to see
where the water was coming from.  I called a contractor friend of mine and 
he checked
the hole and said don't worry, just form it up, drop in the rebar and pour 
the concrete and
what water is in the hole will be displaced by the concrete.

I figured, a deeper hole? , add rebar to the base and take advantage of the 
'bigger hole',
away we go.

I then called another friend (who works at the quick mix plant) and had him 
tell me
how much concrete to order, he told me between 13-14 yards (two trucks) and 
left
to set up the delivery.

Well, we finished pouring and formed off and finished the top with a 5' x 
5' top above the
ground and a massive base below,,, yep,, all 14 yards went in the 
hole.  Two six packs
of beer and $500 to the batch plant,,,   The tower has KLM monobanders for 
10-20 (6ele
20) and dipoles for 40-160 with the 10m monobander at 85' (25' .25 wall 
monel tubing with
a 20' piece of .25 alum tubing sleeved into it for mounting the 160 
dipole)  20' out of the tower
and 5' inside with a thrust bearing at the top and another one at 4.5 feet 
from the top inside
the tower.  Why two??? well I can remove the orion 2800 rotor and not be 
worried about the
mast 'swaying in the wind' and there is NO down pressure on the 
rotor.  What did this cost?
1 extra thrust bearing and an extra rotor plate.  This is a little extra 
insurance for the price.

And the best thing is :::: NO PERMITS NEEDED,,, the downside of the 
installation is
if the tower ever tips over it's gonna take 1/2 the patio with it, but I 
really don't think this
is gonna happen with the 'small' counterweight on the bottom of the tower...

Bob
NA6T

Bob Smith
A.R.S NA6T
ARRL Life Member
Fort Bragg, California   95437

"On The Air-Conditioned Mendocino Coast, In REAL Northern California"
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