[TowerTalk] Mast slipping

[K7LXC at aol.com]

In a message dated 4/22/2007 9:15:57 P.M. Pacific Daylight Time,  
towertalk-request at contesting.com writes:

>  I don't think the problem is a design flaw with the  2800, I believe it 
not rated for very large 3 element 40 meter full sized  Yagis (including
the SteppIR MonstIR) in strong winds.

>   Orion 2800 rotators failed catastrophically in three different 
installations  in my local area when used with very large antennas
(full size 3 element  40M Yagis and SteppIR MonstIRs).  In each case it
was a result of  40-50 MPH winds typical for this area.  Each failure
occured soon  after installation of the rotator.


    Were the failures in the transmission or what?  While I'm sure it 
happens, I haven't personally been involved with an Orion  failure. And yes, they're 
not a prop pitch but better than most other rotators  available. 

>  "Square feet" is an inadequate rating for  rotator capacity.  Very large
antennas distribute wind loads over a  large structure, and considerable
energy is stored in the flexing of very  long elements in the wind. This
stored energy creates heavy torque loads  that overload all but the strongest 
rotators.
 
    Quite true which is why Hy-Gain and Yaesu both  went to Effective Moment 
and K-Factor which are both the antenna weight times  turning radius - a much 
more realistic measurement. 

Cheers,
Steve     K7LXC
TOWER TECH 



 



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