[TowerTalk] Re: First Tower questions

[Alan Beagley]

On 10/25/03 07:59 pm Paul Playford put fingers to keyboard and launched
the following message into cyberspace:

> I believe pipe is measured by ID.  Stay away from pipe.  I use a 2"o.d. x
> 20' mast in my LM470.  My T2X rotator is perhaps 4 feet from the top of the
> tower with a thrust bearing on top of the tower that supports the mast and
> monoband 4 element yagis for 10, 15 & 20.  I aligned the thrust bearing by
> rotating the mast (clamps loose on rotator) and adjusting the thrust bearing
> so there is no mast to tower binding.  I suggest you use the longest mast
> you can obtain because you will always wish you had.

But you have to take the length of the mast into account when 
calculating the wind loading (can't remember where I read this -- ARRL 
Antenna book??): the sq.ft. and force specs for the tower assume that 
the antenna is immediately at the top of the tower, not 10' or more above.

Alan AB2OS