[TowerTalk] Recommendation for mast on bottom mount rotator

K8RI on TowerTalk K8RI-on-TowerTalk at tm.net
Tue Sep 19 23:47:21 EDT 2006


Theoretically it means that if both are subjected to the same velocity wind, 
one will attempt to turn the mast CW while the other will attempt to turn it 
CCW with the same force if they are both pointed directly into the wind. 
However in the real world The wind rarely blows at the same velocity even 
with an elevation difference of only 10 feet.  Add to that gusting, element 
elasticity, and mast elasticity and the results are far from being as 
predictable as the math says they would be in a steady state.   Even though 
they are mounted on opposite sides of the mast they are just as likely to 
end up at times trying to turn in the same direction.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com (Use return address from home page)


> Ok, thanks Mike. I now know what alternately means but I don't see how 
> that
> will alleviate any torque issues on the mast. What am I missing?
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com [mailto:towertalk-
>> bounces at contesting.com] On Behalf Of Mike Fatchett
>> Sent: Tuesday, September 19, 2006 9:54 PM
>> To: 'Gary Schafer'; K7LXC at aol.com; towertalk at contesting.com; K8RI-on-
>> TowerTalk at tm.net
>> Subject: Re: [TowerTalk] Recommendation for mast on bottom mount rotator
>>
>> Mounting one antenna on one side of the mast and the next on the opposite
>> side etc so the boom to mast clamps alternate.
>>
>> Mike W0MU
>>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com
>> [mailto:towertalk-bounces at contesting.com] On Behalf Of Gary Schafer
>> Sent: Tuesday, September 19, 2006 8:50 PM
>> To: K7LXC at aol.com; towertalk at contesting.com; K8RI-on-TowerTalk at tm.net
>> Subject: Re: [TowerTalk] Recommendation for mast on bottom mount rotator
>>
>>
>>
>> > >  Remember this mast has to do basically what  the top mast does. It
>> > > is
>> > one
>> > long torsion bar.
>> > That and with a thrust  bearing at the top the tower will end up
>> > supporting all the extra weight  of the masting.
>> >
>> >
>> >         Umm, I'll go with the long  torsion bar. BTW, mounting
>> > antennas alternately up a mast goes a long ways to  minimizing torque
>> > since they'll cancel each other out. (Article in QEX or QST by  Dick
>> > Weber, K5IU, PE.)
>> >
>> > Cheers,
>> > Steve    K7LXC
>> > TOWER TECH
>>
>> What do you mean by "mounting antennas alternately up a mast"? Pointing
>> them
>> at 90 degrees to each other?
>>
>> 73
>> Gary  K4FMX
>>
>>
>>
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