Jerry,
You are overlooking one important factor: the inertia of the
weight. Recall F=MA. First comes the force, then the acceleration, and
third the motion. If the M is considerable, enough Force is needed to
first accelerate the weight then move it that will break the wire. The
spring works on a slightly different principal. The M is that of the wire
which is insignificant. You only tension the wire with the spring so that
the catenary is the same as it would be without the spring. Then a sudden
pull will imedately stretch the spring, the tension is increased only a
very little, whereas a sudden tension will not move the weight fast enough,
the tension increases, and it enough, the wire breaks. My antenna with the
#22 wire broke with a weight on it. I added the spring first and it didn't
break any more, but after that I changed it to #14 wire. I say that to use
both is the best approach.
Chas, W1CG
At 03:33 PM 9/10/2004,
[hidden email] wrote:
>Weights and springs both work to tension wire antennas...Weights are said
>to have the disadvantage of "rebound", but I have never experienced that
>here in the northeast...Springs increase the tension on the wire
>tremendously as the tree sways and the further the tree sways, the
>greater the tension...This can stretch the wire and exceed the breaking
>point of some element of the antenna assembly...The tension will always
>be the same with a weight, no matter how far the tree sways...For the
>last 4 years I have had a 30 meter dipole up using a 2 gallon plastic
>orange juice container filled with water and anti-freeze...Works for
>me...
>
>Jerry, wa2dkg
>_______________________________________________
>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_______________________________________________
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.htmElecraft web page:
http://www.elecraft.com
Locked
