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[TowerTalk] Antennas on a crank-up

To: <towertalk@contesting.com>
Subject: [TowerTalk] Antennas on a crank-up
From: rmaple@webspan.net (Rich Maple-N2YAP)
Date: Wed, 15 Apr 1998 20:29:06 -0400
K7LXC wrote:
> 
> In a message dated 98-04-15 08:59:59 EDT, MALEXANDER@HEALTHDYNE.com writes:
> 
> > I am getting set to put up a 100' aluminum crank-up tower.  On the top,
> >  at 100' I plan to put a Force 12 Magnum 620/340.  Up from that, about 8
> >  feet -- will go a Force 12 4BA.  I chose these antennas because of the
> >  decreased wind loading, as I am (still) a little nervous about having
> >  those up at the tippy top swayin' in the breeze with no guy
> >  wires....this is my first attempt with a crank-up tower.
> 
>      You should be nervous. What manufacturer and model number is the tower? I
> think Heights is the only aluminum crank-up manufacturer but I can't find a
> hundred-footer in their catalog. They have a 116 foot version (6 sq.ft.) and a
> 104 footer (8 sq.ft.) so I'm not sure which one you've got.
> 
>       Nevertheless in case it slipped past you, the 620/340 is a BIG antenna
> system (13.4 sq.ft. and over 100 pounds). So the only way you can mount ONE of
> your antennas is to crank it down significantly. You might want to read Roger
> Cox's and Bruce Horn's articles on crank-up loading and derating. They're a
> buck each from TOWER TECH. Mounting both antennas would mean cranking it down
> even more.
> 
>       BTW, Waukesha County is an 80 MPH wind speed zone. According to the
> Heights literature, they "are engineered to withstand an 80 MPH windload
> pressure". They also mention guying but I would certainly check with the
> factory (talk to Drake Dimitry) with your proposed installation.
> 
>       Aluminum towers are like noodles - they move and sway all over the
> place. If you want some real excitement in your life, try climbing a self-
> supporting aluminum tower. Yee-ha!
> 
>       Bottom line? Talk to the factory to get their recommendations and be
> real conservative with your installation. You've got way more antenna than
> tower at this point - reality strikes.
> 
> 73 and GL,  Steve  K7LXC
> 
> --
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Steve do you have a list of the articles you offer for sale?


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