[TowerTalk] tower base concrete or not

[roy.thistle at utoronto.ca]

I am installing a 40 foot tower. It will not be self supporting. It will
be bracketed to the roof/wall, and I will use guy wires. The tower is in
10 foot sections, and is about 50 pounds per section. It looks similar to
TV type tower; but, it is more reinforced with cross-braces, and is
heavier.

I have dug a 3 foot by 3 foot by 6 foot hole. The hole has been there for
about a month, and shows little sign of collapse. The soil seems firm and
compacts well.

I was wondering the following, after having read many of the posts on
installing towers, and visiting some web sites.

Do I need to use concrete? Can I just drop 4 to 5 feet of the bottom
section of the tower in the hole and back-fill with gravel. I am asking
because I have seen many TV type towers (some over 30 feet high) installed
with a roof or wall bracket, and the bottom section buried only about 18
to 24 inches down in the ground. Some of these towers are holding a 12
foot steel mast, and a yagi...some are holding a couple yagis and rotors.
I have climbed many of them, until I realized how flimsy the installation
was. Never the less, some of them have been up for almost 50 years. 

I think that there was a previous thread wondering about the amount of
concrete that is required?

r.