[TowerTalk] Wire size for 800 meter long wire

[David Robbins K1TTT]

Run these specs through your nomographs...
12 ga insulated copperweld at 22 lbs per 1000' with a breaking strength of
900lbs
or
10 ga insulated copperweld at 35 lbs per 1000' with a breaking strength of
1231lbs
both available from Clifford of Vt under imsa spec 28-3.  insulation is
really tough black hdpe.  Standard reel length is 5000', but they will cut
to length.


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
 

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Barry Merrill
> Sent: Monday, October 10, 2005 21:14
> To: TOWERTALK at contesting.com
> Subject: [TowerTalk] Wire size for 800 meter long wire
> 
> Using the nomograph in the ARRL Antenna Book,
> which only goes up to a SPAN of 1000 feet
> (and only after an hour did I see that "SPAN" is
>  one HALF the distance between end points),
> I can't find any wire that can survive that SPAN,
> when you've only got 50 feet for sag.
> 
> I've got a distance of 2400 feet for the long wire
> between two 70 foot high bluffs on opposite sides
> of a saltwater inlet that is shoaled and un-navigable.
> 
> I plan on 100 watts, and I'd like to use small wire to
> make the wire less visable, but using the maximum
> SPAN of 1000 feet with #12 wire, the chart says that
> to keep the sag less than 50 feet, I need 400 pounds
> of tension (as if I could every supply that force!),
> but the recommended #12 tension is only 75 pounds.
> 
> using something as large as #12 wire,
> for the maximum table SPAN of 1000 feet,
>   (my actual SPAN is 400 meters)
> the chart says that to keep the sag to less
> than 50 feet, I'd have 400 pounds of tension;
> unfortunately, the recommmended tension is
> only 75 pounds (at 10% of breaking strength).
> 
> Or, my tension would be 400/750= 53% of breaking
> strength of #12 wire.
> 
> So, what can I do?  Is there a strong, light wire that
> will work for 800 meters with 50 foot sag?
> 
> 73
> 
> Barry, W5GN
> 
> 
> 
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