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Two towers

To: <>
Subject: Two towers
From: (
Date: Mon, 23 Dec 1996 23:05:08 -0500
In a message dated 96-12-23 17:02:27 EST, you write:

>Hy Gain 204BA
>Cushcraft 402CD
>Cushcraft A3WS with A103 (30 meter add on kit)
>Hy Gain Explorer 14
>(1)  US tower TX 455
>(2)  Rohn  HDBX 48 
>My questions are these:
>I have one Ham 3, modified to a ham IV by Cats, I plan to buy a Ham IV
>reconditioned from Cats.
>Are these two rotators  sufficient?

>I WOULD LIKE to put the 2 el 40 and the 4 el 20 on the TX455 as it is a
>little taller... with the Ham IV rotor.  What is your opinion?

>I will put the Explorer 14 and the WARC antenna on the Rohn HDBX 48 with the
>already owned Ham 3, upgraded inside to ham IV.. 
>How on that setup?
>What type of mast do you suggest.
>I prefer (for financial reasons) to not buy aluminum mast.
>How long mast for each tower?
>Any other suggestions or comments?
>I plan to dig two holes each 3 X 3  X 3.... wat about that?

Floyd --

    First things first.  You're in a 100 MPH wind speed zone and within 100
miles of a hurricane oceanline.  Every decision you make should take that
into consideration.  

       Neither of your towers are rated at 100 MPH.  The HDBX is rated at 18
sq. ft. at 70 MPH and the TX455 is 18 sq. ft. at 50 MPH.  You can interpolate
for loads at 100 MPH but by then, these towers will have little capacity
left; let alone the stacks of antennas that you're proposing.  In addition,
Rohn wants a maximum boom length of ten feet on the HDBX.  In other words,
you really can't do what you want to do without violating the Prime Tower
Directive, "do what the manufacturer says". 

       The wind forces that we're talking about are tremendous.  For example,
70 MPH has a wind pressure of 20 pounds per square foot; 100 MPH has a wind
pressure of 40 PSF.  Don't take any shortcuts in this area.

   You need to have the manufacturer's specifications in order to do any
planning and for specifications like what size base you need for each tower.
 TOWER TECH has Rohn catalogs for $5.00 and it has the Rohn info that you
need.  Get the TX455 info from US Towers.

    Masts and rotators are far down the line until you get these preliminary
wind speed/loading issues resolved.

    I'm going to post this to TowerTalk because of the nature of the
questions and issues.

73,  Steve  K7LXC

     TOWER TECH -- professional tower supplies and services for amateurs

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