Rys want to use this twested military telephone line for a two wire beverage
, I agree Jim, on one direction the impedance between the two wires and the
ground will be more or less the same as with any other type of wire but Rys
want to use also the 150 ohms twisted line to return the signal from the far
end to make a reversible beverage.
Like Rys I tend to believe this is the best way to make a two wire beverage
, at least very simple to set up , very reliable , very cheap! the problem
is that I have never seen any description , article etc (except RA6LBS),
most papers are showing two wires home made lines , 450 ladder lines ,
sometimes coaxial cable are we missing something ??.
I bought a roll for almost nothing, first I thought it was from the French
army but now it think this US military surplus, it is probably easy to find
also in the US. I measured 150 ohms impedance. I do not know what
the attenuation of this type of transmission line is ?
Like Rys I would appreciate any comments.
73
jacques F6BKI
----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: <topband@contesting.com>
Sent: Tuesday, July 27, 2004 2:49 PM
Subject: Re: Topband: two wires Beverage
> On Tue, 27 Jul 2004 07:33:53 +0200, Ryszard Tymkiewicz wrote:
>
> >The similar line used in French Army has Jacques F6BKI and in
> > both cases the impedance was about 150 ohm.
>
> When you're thinking about the impedance, remember that this is the
> impedance of that line when used as a twisted pair transmission line. That
> will NOT be the impedance of a Beverage antenna that you build using
> that wire -- in fact, the impedance of the Beverage will likely be pretty
close
> to what it would have been if you had used a single conductor of the same
> electrical size (that is, something on the order of 400-600 ohms,
> depending on how you rig it with respect to earth). The beauty of using
the
> wire you suggest is that it has robust construction.
>
> One other point, and maybe others can comment. If the cable is a twisted
> pair, the twisting may cause the electrical length to differ from that of
an un-
> twisted wire.
>
> Jim Brown K9YC
>
>
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