Ken Scharf wrote:
K7MEM wrote:

wrote:

I just purchased a tilt-over mast that I'd like to erect:

The base section begins with a 16"-square piece of 1/2" steel with four
holes on 12" centers and is welded (with four pieces of steel, sorta
like rocket fins) to a pipe which rises 17.5' to the pivot point.
The tilting part extends 16' further. All of the above pipe is 2 3/8"
in diameter, but a smaller-diameter pipe (for mounting a rotor?) sticks
out the top end of the tilting section another foot or two.

Can someone suggest how big a blob of concrete and how much rebar I'll
need at the bottom to erect this mast to be freestanding?



I have a Triex W-51 Crankup in my yard. Collapsed it is about 22 feet
high
and extended it is 51 feet. The manufacturers recommendation for the
"blob"
of concrete is 3 feet by 3 feet by 5 feet deep, roughly. This is about
1.5 Cubic Yards of concrete. I don't have the specs handy, but I believe
the rebar mount extended about 3 feet down and was centered so that it
is at least 6 inches from any side. To make sure that everything sits
where it is suppose to, and will be plumb when erected, the rebar mount
was bolted to a 2" x 6" wooden form, leveled properly, and then the
concrete was poured around it.

There is a reflector around called something like "Tower Talk" that would
be able to give you more details and advice. However, I don't remember
the
link. Maybe someone else can supply it.

It's a fairly big job and takes a bit of planning.

Keep in mind that some cities engineering departments are ultra
conservative and will double or triple(!) their requirements over
what the tower maker recommends. This happend to a friend of mine
who ended up with about 3-4 cubic yards being poured for a 20' crank up

Yes, I found that part very interesting. There are a lot of houses and
schools in my area, but there are no specific covenants on erecting
structures. I have a cul-de-sac lot and had the necessary room on
one side of my house.

So I thought I would check with the city. I was really prepared.
My documentation included the designers calculations and California
compliance certification. I live in the Phoenix area, but thought that
this would be sufficient for approval. California is usually
a little tighter on their requirements. Anyway, when I went downtown
to the city planners, it turned out that, because the tower and antenna
were not for commercial use, and there was no electrical wiring (I use
a battery powered electric drill to crank the tower), there were no
structural requirements or inspections. So I just followed the
manufactures recommendations.

When the tower is cranked down, my antenna nestles itself within a
group of trees, and is barely noticeable from the street. Most people
that come to my house, don't notice it. This also seems to keep the
neighbors happy, and, so far, I haven't had any complaints (knock on wood).

If you go to http://lists.contesting.com/archives/html/Towertalk/ and
do a search on "tower base recommendations" you will find some very
good discussions on things to consider when erecting a tower.

--
Martin E. Meserve - K7MEM
http://www.k7mem.com
(remove _nospam_ from my email to reply)