[TowerTalk] Bad Breath?

[K7LXC@aol.com]

In a message dated 99-02-16 08:25:28 EST, k4oj@ij.net writes:

> every time I see those pictures of a Telex rotor on a pipe mount (that
>  piece attached to the bottom of the rotor grabbing a vertical pipe for
>  mounting) and then a mast with an antenna on it above the rotor I cringe...
>  
>  the only thing I do not like about out of tower (tree) rotors 
>  is that there is nothing to hold onto the mast if you don't have the rotor
>  there...on a tree this is extra crucial.
>  
>  the ongoing debates as to whether or not two thrust bearings on a tower all
>  point to the stability achieved by having two points of stability for your
>  mast far outweighing one certainly quantum leap when you have nothing
>  stabilizing a mast above rotor....if you mount to a tree in my opinion you
>  might as well marry a top section of tower to the top of the tree as a
>  means to obtain this stabilizing your mast really outta have!
>  
      The reason that you would have two thrust bearings is so that the mast
is held securely in the event that you have to do a rotator swap. This is
particularly handy with a big mast and a stack of antennas where the center of
gravity is above the top of the tower. 

      I mast-mount tree installations all the time and prefer the TailTwister
because of its added physical strength over the Ham IV. When I was at Hy-Gain,
we destruct tested a T2X with a lateral load to see what it would take. It
finally broke right at the neck just above the top bell housing at a force of
3,000 ft.lbs. That's magnitudes over what you would encounter with a typical
small to medium sized HF yagi mast mounting situation. It's plenty strong
enough for mast mounting.

       If anyone is interested in a write-up on this test along with lots of
other rotator information, my 3-part reprint from my "Up The Tower" column is
CQ Contest magazine is available for a buck from Tower Tech, Box 572,
Woodinville, WA, 98072. 

Cheers,  Steve    K7LXC
Tower Tech
Champion Radio Products


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