[TowerTalk] [Tower Talk] Hazer and mast

[K7LXC@aol.com]

In a message dated 05/23/2000 8:34:03 AM Pacific Daylight Time, 
w8tts@gwis.com writes:

> I currently have a Glen-Martin hazer on a tower with a Mosley
>  TA33-JR-N-WARC mounted just above a thrust bearing, which is about 3'
>  above the 
>  G-8000S rotor.  What I would like to do is add a mast to this, so that
>  there is 
>  an additional 10 feet above the top of the hazer thrust bearing, and
>  mount the 
>  TA-33 at the top of the mast.  This would do a number of things for me 
>  including being able to adjust the height of the antenna a little,
>  getting the
>  antenna 10' higher without adding tower, and as I do now being able to
>  lower the antenna if there is a high wind warning.  Yes I know, the wind
>  load on the antenna (96lbs at 80MPH) isn't much, but better safe than
>  sorry.
>  
>  Now my questions.  Is it safe to go that high above the thrust bearing,
>  which is a Glen-Martin, with a mast and antenna?  And, I'm looking at
>  using 1-1/4" Schedule 80 pipe for the mast, is this over kill?

      Overkill? Not even.

     First of all, Summit County is a 70 MPH windspeed zone, the lowest they 
give, so no big deal wind-wise.

     The MARC (Mast, Antenna and Rotator Calculator ) Program says that 
you'll have 12,056 in-lbs of bending moment on the mast and you'll need a 2" 
mast with a yield strength of 39,000 psi and .120" wall. The best you can 
hope for with a pipe is about 35,000 psi yield but if you go with 1.5" 
Schedule 80 or so pipe (about 1.9" OD) that has more wall, you'll probably 
get away with it.

     Someone (N1LO?) posted some excellent info recently about pipe strength 
so you should check the archives for more info. 

     As for the suitability for use with a Hazer, you need to check with the 
manufacturer. 

Cheers,   Steve    K7LXC

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