[TowerTalk] 4 square or yagi ??

[Joe Subich, W8IK]

At 04:06 PM 10/22/97 -0400, you wrote:
>
>Just out of curiosity, why should the 40M beam be mounted *above*  the
>tribander? I have two friends locally who have identical 100' Rohn 45 towers
>with stacked TH7 and Cushcraft 2-EL 40M beams. One has the TH7 on top and
>the other has the 40M beam on top. No reason from the former. The latter
>says he wanted the heavier beam on the bottom to reduce mast loading. Any
>other good reasons to stack one over the other?
>

Two reasons ... 

1) the Cushcraft 2-el 40 has significantly less windload than the TH7 
   and thus stacking it on the top will impose less stress on the mast. 

2) the added height is more important on 40 than on 10 ... relative to 
   wavelength.  On a 100' tower, the TH-7 may already be "too high" on 
   10 meters (ca. 3 wavelenghts) where the 2-el 40 is only 3/4 wave up. 





73, 

   ... Joe Subich, W8IK  ex-AD8I
       <w8ik@ibm.net>

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