[TowerTalk] RE: mast material

[K7LXC at aol.com]

In a message dated 1/21/04 7:33:43 AM Pacific Standard Time, 
kenneth.lowrey at wright.edu writes:

> I have a 15 foot piece of 1/4" thick aluminum mast.  I am considering using 
>  this to come out of 50 feet of Rohn 45.  I plan to put the Mosely CA-53 
beam 
>  on it along with an 11 element 2 meter beam.

     Sure - as long as the HF beam is right at the top of the tower. You can 
put the 2M antenna up the mast anywhere you want. 
>  
>  What is the group's experience/thinking about using aluminum mast?

     It's good for *some* mast applications. The problem is that 6061-T6 
aluminum only has 35,000 pounds of yield strength - good for light mast loading 
but not much else.

     A 6 sq.ft. antenna 10 feet up a mast can exert 50-60,000 pounds of 
bending moment depending on windspeed/pressure so aluminum is pretty wimpy for that 
kind of application. 

     I've got a mast calculator program available if you want to play some 
mast/antenna loading scenarios. The MARC (Mast, Antenna & Rotator Calculator) 
Program is available from  <A HREF="http://www.championradio.com">
www.championradio.com</A> for ten bucks. 

Cheers,
Steve       K7LXC
Champion Radio Products