[Antennas] Optimal longwire for QRP

2002年5月13日 21:36:47 -0400

At 09:46 AM 5/13/2002 -0700, Chris BONDE wrote:
>Now, if what you are talking about is what some Americans call "bungie" 
>cords then I always have couple in the boot. But I do remember pictures 
>of some cars with belts on the hood running parallel to the win'screen.
>>Do you put the shock cords in parallel to give better weigth distrubution 
>or as a saftey precausion as the cords deteriate in the sun and rain?
>>Chris,

The more shock cords in parallel, the more force required to enlongate the 
cords a given amount. I started with one, applied enough force at the 
other end to keep the wire from drooping too low, and the cord stretched 
too much and the wire still drooped too much. Added one, it took twice the 
force to stretch the same amount, but it wasn't enough. Kept adding cords 
until I had six, in which case I could apply enough force to straighten the 
wire reasonably. I had a pulley and counter weight of about 20 pounds on 
the other end and it supports the counter weight. When the tree sways in 
the wind, the cords first stretch and finally the weight moves up a 
bit. But it has inertia, and the cords take up the shock of first 
movement. At least now the wire doesn't break.
73, Chas, W1CG