[TowerTalk] AB-577/GRC Engineering Specs?

Jim Lux jimlux at earthlink.net
Sat Apr 15 13:51:53 EDT 2006

At 08:31 AM 4/15/2006, Michael Braun wrote:
>Dear TowerTalk subscribers,
>Hi - I'm Michael Braun, N3CA.  I am a 17 year old ham and enjoy
>contesting as my primary interest.
>About 3 months ago I was lucky enough to procure one of the AB/577 GRC
>Military masts from a good friend and we successfully installed it at
>48 feet, assuming that a permit would not be required because it is
>I am writing to ask if anyone knows any Professional Engineers that
>are familiar with the AB/577 GRC 48 foot mast and may have done some
>complete engineering studies on it related to wind loading and other
>factors, or anyone who has had such studies done for themselves..
>While I know that the 6 square feet of antenna I have at the top (48
>feet) can be adequality
>handled by the mast, I need to prove this to my county.

Inasmuch as that is a standard military design, have you checked to see if 
DoD did any analysis?  I'll bet that someone figured out what all the loads 
are, etc.

While you don't have a lot of cash, you might have a lot of time to go 
tracking down the documentation.
I'd start with looking for the official documentation for the mast: user 
guides, field manuals, procurement specifications, etc. There will be a 
sheet in there that describes which DoD facility originated the document, 
and that will give you a place to start calling.  Someone, somewhere did 
calculations to arrive at the procurement or manufacturing specifications.

You might start by tracking down TM 11-5820-538-12 which is the operator 
and organization maintenance manual.

This is a fairly old piece of gear (60s), so it's unlikely that what you 
need will be online.  You're probably going to have to find some 
documentation center or library and have them send you a copy.  Although, 
since a lot of hams are using them, someone might have scanned the documents.

Then, it will be up to you whether you can take those documents and 
analysis to the local permitting agency and see if they'll take the 
"official government specifications" in lieu of a new engineering analysis. 
($2000 is quite reasonable for that, by the way..  You can see that 
engineering isn't all that bad a profession)

Jim Lux, W6RMK 

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