Antenna Suspension

[Unifiedtx]

I am using a Carolina Windom 80 suspended with 3/16" nylon rope through
stainless steel eyehooks up 50' between two large oak trees.  These trees are
approx 123 feet apart.  Because I am located in hurricane alley and subject to high
winds, I would like to remove the permanent tiedown on one of the trees and
tie a weight to the rope.  I would like to know how much weight should be used.
 What kind of weight (how many bricks or what-have-you).  Thanks.  Roy Morris
 W4WFB  
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[Ron D'Eau Claire-2]

There may be some power line people here who can give you're a very specific
answer. It has to do with allowing the right amount of "sag". Consider that
it takes infinite "pull" to hold a flexible wire exactly horizontal between
two supports. That is, it's impossible. The other extreme is zero pull
needed if it's allowed to lay on the ground.

What I've always done is to "eyeball" it. As you pull harder you notice that
there's a point at which pulling a LOT harder, hardly makes a difference in
the droop. At that point I back up and let it droop just below the point
where I notice the amount of pull needed escalates quickly to make it any
"tighter".

With rocks/bricks in a bucket, you can see that you reach a point where
you'd need to add 50% more bricks to make the wire visibly any straighter.
Don't do that, of course. Let it droop.

As I said, the power line and telephone people have specific rules that they
use based on the wire, span, etc. If no one here turns up and you really
want to measure the strain that is optimum for a specific situation, I'd
suggesting searching the 'net or a technical library for information of
stringing phone and power lines.

Ron AC7AC

-----Original Message-----
I am using a Carolina Windom 80 suspended with 3/16" nylon rope through
stainless steel eyehooks up 50' between two large oak trees.  These trees
are
approx 123 feet apart.  Because I am located in hurricane alley and subject
to high
winds, I would like to remove the permanent tiedown on one of the trees and
tie a weight to the rope.  I would like to know how much weight should be
used.
 What kind of weight (how many bricks or what-have-you).  Thanks.  Roy
Morris
 W4WFB  


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[Bruce Rattray]

Hi Roy - I had that set up when my QTH was in New Hampshire...I tied 2
window sashe weights to one end and it seemed to do the job riding up
and down in the wind...course we never had any hurricanes...72 Bruce.

72/73 - Bruce ve5rc/ve5qrp - I believe in the KIS principle.
         ** Enter QRP-Canada's "RUN with RAC" contest -            
            details at http://www.qrp-canada.com  ***

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Thursday, September 09, 2004 1:21 PM
To: [hidden email]
Subject: [Elecraft] Antenna Suspension

I am using a Carolina Windom 80 suspended with 3/16" nylon rope through
stainless steel eyehooks up 50' between two large oak trees.  These
trees are
approx 123 feet apart.  Because I am located in hurricane alley and
subject to high
winds, I would like to remove the permanent tiedown on one of the trees
and
tie a weight to the rope.  I would like to know how much weight should
be used.
 What kind of weight (how many bricks or what-have-you).  Thanks.  Roy
Morris
 W4WFB  
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[Stuart Rohre]

You can find the breaking strength vs. gauge of wire for copper in wire
tables from the manufacturers.

You can also find in some catalogs what the safe tension in pounds is, and
the weight should not exceed the working tension rating.

A wire is going to assume a natural sag of a centenary, and as has been
stated by Ron, you can pretty well tell when you have reached the safe point
on tension in straight pull on the antenna wire.

You can get gauges to measure exactly, but after some experience of breaking
an antenna wire, you will know the right touch and when to stop without
needing a gauge.
73,
Stuart
K5KVH


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[Rich Ardolino]

Here is another tip. I live in NJ where slingshots are classified as
"firearms" in same catagory as handguns (crazy law, I know!.... but you have
to be crazy to live here in the 1st place) , so I need to minimize how often
I use my slingshot launcher since I have cops living in my neighborhood.
Also, I try to keep my wire antennas "low profile" (no pulleys and buckets
of rocks or springs). So after getting the support rope up I use it to pull
up a second support line, tied in parallel with the first, but only put
tension on one line. When it eventually chafes and breaks the load will
automatically transfer to the 2nd line, which is now ready to pull up a new
2nd  support line, thus eliminating the need to use the slingshot launcher
again. Works for me, your milage may vary.

Rich  K2CPE
K2 #1102

>Subject: [Elecraft] Antenna Suspension


> I am using a Carolina Windom 80 suspended with 3/16" nylon rope through
> stainless steel eyehooks up 50' between two large oak trees.  These trees
are
> approx 123 feet apart.  Because I am located in hurricane alley and
subject to high
> winds, I would like to remove the permanent tiedown on one of the trees
and
> tie a weight to the rope.  I would like to know how much weight should be
used.
>  What kind of weight (how many bricks or what-have-you).  Thanks.  Roy
Morris
>  W4WFB


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[Charles Greene]

W4WFB,

I have two antennas supported by one tree each.  On one I use a 1 gallon
chlorox bottle which I fill with water to get the desired weight and a
large pulley.  The pulley is supported by another rope going around a
limb.  However, I noticed that the weight did not respond fast enough to
relieve the strain imposed by the tree swaying, and it broke a #22 wire.  I
replaced the wire with a #14 insulated wire and installed rubber tie down
straps about 3' long with steel hooks at the fixed end of the antenna.  I
used 4 of them in parallel.  On the other tree the antenna was longer, 90'
and the weight on the antenna, #14 insulated stranded antenna wire helped
some, so I just used the tie down straps and no weight.  It was a bigger
tree and didn't sway as much in the wind.  Both been up for over three
years.  You have to replace the rubber tie down straps periodically.

GL,

Chas, W1CG

At 03:20 PM 9/9/2004, [hidden email] wrote:

>I am using a Carolina Windom 80 suspended with 3/16" nylon rope through
>stainless steel eyehooks up 50' between two large oak trees.  These trees are
>approx 123 feet apart.  Because I am located in hurricane alley and
>subject to high
>winds, I would like to remove the permanent tiedown on one of the trees and
>tie a weight to the rope.  I would like to know how much weight should be
>used.
>  What kind of weight (how many bricks or what-have-you).  Thanks.  Roy
> Morris
>  W4WFB
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

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[G3VVT]

 
Use a basically similar method of rubber tie down straps here. Sent  this in
reply off the reflector:
 
I use some heavy duty luggage elastic ties to provide for the movement of  
the supporting 50ft fir tree on my 40/80 trap dipole. Have the antenna centred  
over the house with a fiberglass pole on one of the chimney stacks to support  
the dipole centre. OK at the rear of the house with the garage as a support,
but  had to use a tree as the support at the front. Took the antenna end  
supports down after two years for inspection and were still OK. Will recheck  
after another couple of years.
 
Presume the same type of ties are available in the USA. These are three  feet
long with a plastic covered steel hook on each end. I closed the hooks to  
form an eyelet at each end. Works for me though we do not get much in the  
hurricane line in the UK normally.
 
Regards,
Bob, G3VVT
K2 #4168

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