[TowerTalk] High VSWR

[dj7ww at t-online.de]

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 at telus.net>
An: "towertalk at contesting.com" <towertalk at contesting.com>

From: "dj7ww at t-online.de" <dj7ww at t-online.de>
To: Jim Thomson <jim.thom at 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.