Jim,
You did not mention before that the installation of a vane becomes necessary
when you mount the boom at it´s center!
With that vane I agree that the antenna is torque balanced but you need more
counter weight.
With the boom just mounted at it´s center, the wind pressure on the boom will
be much higher on the side with the longer elements whatever counter weight you
place on the side with the shorter elements and cause turning force on the
antenna..
To prevent that I mount the antennas on a temporary mast on the ground and
shift the mounting point until the antenna is not turned anymore by wind.
If that is finished I counter weight the boom at the director ends until the
boom is straight when hung on my overhead rope so mechanically balanced.
Therefore none of my 8 long boom yagis is mounted at the boom center and even
the 40m yagi is mounted 1m off center.
73
Peter
-----Original-Nachricht-----
Von: "Jim Thomson" <jim.thom@telus.net>
An: "towertalk@contesting.com" <towertalk@contesting.com>
From: "dj7ww@t-online.de" <dj7ww@t-online.de>
To: Jim Thomson <jim.thom@telus.net>
<That is a bad idea, the torque force on the rotor under high winds will become
much larger.
<73
<Peter
## Nope. It will reduce torque down to virtually zero. In his case,
it gets even better, the LPDA
is mounted ABOVE the mast, instead of the SIDE of the mast. Tq will
be zero.
## Two ways to tq balance a yagi. 1- mount at center of boom, and
use a counterweight at far end of boom, the light end.
2- mount boom at CG, then use a sail / vane at far end .....short
end of boom.
## I have used both methods with great success. Both designed with
software from DXE + also K7NV.
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