[amsat-bb] Re: springtime project

[John B. Stephensen]

I did something similar when I lived in Los Angeles. I mounted a 5-element 
10-meter beam under the satellite antennas on the tower in the attached 
photo. This required increasing the length and wall thickess of the mast and 
changing the azimuth rotator to a more powerful version. Note that the tower 
is the heavy-duty model and has an extension to accomodate a thrust bearing. 
The tower was not fully extended in that configuration so that the top of 
the new mast didn't exceed the original height of 45 feet.

However, I reread a mechanical engineering textbook from college and did the 
necessary calculations to prove that it wouldn't blow over before trying it. 
The wind load has to be kept close to the tower. CP yagis have a much lower 
wind load than a 3 foot dish so this my not work in your case.

The 6 m beam or the 3 foot dish could be mounted separately as I did in the 
photo.

73,

John
KD6OZH

----- Original Message ----- 
From: <w7lrd at comcast.net>
To: "AMSAT-BB" <AMSAT-BB at amsat.org>
Cc: "NW VHF" <PNWVHFS at googlegroups.com>
Sent: Tuesday, January 20, 2009 08:42 UTC
Subject: [amsat-bb] springtime project


> Hello
> Before I reinvent the wheel I want to run this project by you.  My current
> satellite antenna system is on a 15 foot tripod using a G5400  az/el
> rotors.  Consists of  14 el cp 2M yagi, 40 el cp 70 cm yagi, 3 foot dish
> for S band 16 turn helix for L band.  I want to change the tripod to a 30
> foot tower and add a 5 el 6 M beam.  Question- put the satellite antennas
> just above the top of tower and the 6M beam above the satellite ants. high
> enough as not to interfere with the sat. antennas when rotated in
> elevation.  Then if possible have the whole thing being able to tip over.
> Has anyone come close to doing something like this?  Or any ideas.
> 73 Bob W7LRD
> CN87
>
>
> --
> "if this were easy, everyone would be doing it"
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