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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