[TowerTalk] MA-550 Questions- Part 1 Second Try

[Steven H. Sawyers n0yvy]

I apologize for the formatting of the previous message - have
had some problems switching between Email programs.

Reformatted message:

I have just finished telling a gentleman in the local club
that his MA-550 is useless as a free standing antenna
support in an 80 MPH wind district.

He is not real happy with me. 

I am not real happy with a manufacturer that sells a product 
optimistically rated at 50 MPH in country were the minimum 
design wind speed is 70 MPH or almost double the wind force.

I do not recommend the product.

Steven H. Sawyers PE

Additional information:

I gave up a day of vacation to try to solve this 
gentleman's problem with the local building department 
and did a complete analysis using EIA-222 Rev F and 
the AISC Steel Construction Manual.

I don't charge for my work for local club members.

The wind loads and the stresses don't stack up, so I was
unable to certify it meet the required standards.

We are currently planning on house bracketing the tower
at 18 feet and limiting it to 40 ft max height with a 6.7 sq ft 
antenna wind load. This will meet the 80 MPH wind zone.

The house will obviously have to be reinforced ala QST 
article.



>BillSavage,
>K3AN
>wrote:
>> 
>> I've been reading the posts for the past two months, and have read the
>> archives on contesting.com.  I am about to purchase my first ever tower,
>> and have a number of questions.  Thanks in advance for your opinions and
>> recommendations.
>> 
>> I have just moved to a country "estate" which consists of a house in the
>> middle of a 3 acre yard.  No trees except a 40' oak along the back edge of
>> the property, adjoining a cornfield.  Neighbors on both sides, on
>> equivalent size lots.  My property is 210 feet wide, and I have about 220
>> feet from the back of the house to the back of the lot.  There are no
>> antenna covenants; a few nearby neighbors have 8' satellite dishes and/or
>> 30' or 40' house-bracketed TV towers.
>> 
>> I'm planning to install a free-standing U.S. Tower MA-550 crank-up tower
>> with the manual crank option.  The MA-550 is the XYL's requirement.
>> 
>> 1.  I would like to use the '550 as a center support for an 80 Meter
>> dipole, so I guess I want the MAB instead of the MARB base.  The MARB base
>> puts the rotor at the bottom, and rotates the entire tower.  Is it feasible
>> to put some kind of loose-fit "collar" on the mast that's above the top
>> section, and tie the center of the dipole to some kind of arm extending
>> from the collar?
>> 
>> 2.  If I go with the MAB mount, and put the rotator atop the tower, what's
>> the maximum safe length of mast I can use and not overstress the rotator's
>> bearings and other parts when I crank the tower over for antenna
>> maintenance.  I'm planning on a Force 12 C3SS beam.  What would be your
>> recommendation for the minimum rotator for this installation?  Would I be
>> better off going to the next one up the capacity chain?
>> 
>> 3.  How do you go about ensuring that the base will be level, and the tower
>> plumb, as you are pouring the concrete and letting it set?  Can you shim
>> the base in some manner after the concrete has cured?  Will these questions
>> be answered in the U.S. Tower planning information packet?
>> 
>> 4.  If anyone has recently purchased a MA-series tower, how long did it
>> take from order to receipt.
>> 
>> 5.  Does U.S. Tower provide, or not provide, an installation instruction
>> manual?  I've seen both answers in prior posts.
>> 
>> Thanks to all respondents.
>> 
>> 73,
>> K3AN
>> 
>> --
>> FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
>> Submissions:              towertalk@contesting.com
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>> Problems:                 owner-towertalk@contesting.com

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>
>--
>FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
>Submissions:              towertalk@contesting.com
>Administrative requests:  towertalk-REQUEST@contesting.com
>Problems:                 owner-towertalk@contesting.com
>Search:                   http://www.contesting.com/km9p/search.htm
> 


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