Date: Sun, 1 Nov 2015 19:47:00 -0500 (EST)
From: "jcjacobsen@q.com" <jcjacobsen@q.com>
To: w8qwdave@casair.net
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Max antenna weight
Dave,
Google and the MFJ/Hy-Gain site are your friends. Hy-Gain recommends the
HDR-300, T2X, or the Ham IV for this antenna.
>From the T2X manual: Max Effective moment is 3400. You get this from the sum
>of turning radius and weight, so 22' times 88 lbs equals 1936, so that's in
>limits. Antenna weight is 88 lbs, so that shouldn't be a problem, given the
>triple bearing race of the T2X. T2X rated at 20 sq ft of area.......
In closing, I am neither an antenna Guru or an engineer, so you should only
consider what is in print, the MANUFACTURES print as in the
manuals.............. other wise, YMMV. OR you could spend the bucks and get a
REAL engineer to run the numbers.
Good luck with the project.
K9WN Jake
## IMO, rating any rotor in max effective moment and or square feet...or max
boom length is absurd. What you want to know is max rotating torque in FOOT
lbs...and max braking TQ, also in FOOT lbs, that’s it.
Any software will tell you asap how much rotating TQ you will have on any
given yagiS......and at any windspeed. Knowing that, its easy to then size a
given rotor for the job. Its also easy to properly torque compensate
the yagi, so it wont twist in a wind. That alone will take a huge load off the
rotor...whether you are trying to turn it in a wind, or hold it steady in a
wind. There really is no excuse these days to produce yagis that are not
tq compensated. Either a software designed plate is installed at the short
end of the boom...just in front of the REF..... OR.... you instead mount the
yagi at the dead center of the boom, then install a counterweight at the
lighter end of the boom, IE; DIR end.
Jim VE7RF
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