In a message dated 96-08-08 01:55:14 EDT, you write:
>A friend here locally had a similar problem with his G1000 rotor on a
>Sommer beam( quite large, has coverage from 7 to 30 mhz) and it failed
>very soon in its' career. Well within the wind spec too, but possibly not
>within the "flywheel" spec. Why bother to specify a wind area when it's
>such a vague spec anyway?
Hi, Don --
None of the rotator manufacturers uses a simple square footage rating
anymore. You can see the disparity between antennas having the same wind
load but vastly different stresses on the rotator; i.e. a 10 meter antenna on
a 40 foot boom vs. a 2 element 40 meter yagi on a 19 foot boom. Nowadays a
calculation that takes weight and turning radius into account is the way to
calculate the appropriateness of a particular rotator. Hy-Gain calls it
Effective Moment that is the product of the weight and turning radius. Yaesu
calls it "K-Factor" and Emoto uses GD2.
>I never seem to hear much about the old Wilson 1000's.....I have one
>turning a 3el 40m at 145' (40' boom, weighs over 300 lbs) and it handles
>it effortlessly, even in high winds. I had it turning a 4-30 Sabre log
>that weighs 1300lbs and it turned it fine but it was only a temporary
>situation until I built my own unit (worm drive, etc). The problem there
>was the log kept turning and would often go another 90 deg or more before
>stopping and I hated to drop the brake on it at full steam like that. But
>I did a few times w/no problems but that's too much like gambling. And
>-40C weather has no slowing effect either. Wish I had a barn full of
>them....
>
The Wilson WR-1000s were one of the few rotators capable of turning big
loads reliably. The Sabre is a commercial rotator that isn't economically
viable for most hams. We all wish we had a barn full of them.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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