[Elecraft] KX1 - We need to develop the ideal antenna

[Geoffrey Mackenzie-Kennedy]

Hi Dale,

K1TD made some measurements back in 1979 on a transmission line made from
dry Zip Cord, and reported that its nominal characteristic impedance at HF
was 105 ohms and its velocity factor was 0.69.

He also measured the loss per 100ft at various frequencies when the line was
terminated by a 105 ohm load (105 +j0).

F MHz     Loss db per 100ft

  3.5                0.7
  7.0                1.8
14.1                4.0
28.1                7.5

Maybe modern ZIP Cord is different, but I hope that this helps.

73,
Geoff
GM4ESD


On Monday, May 16, 2011 at 5:02 PM, Dale Putnam WC7S wrote:


 > Zip cord, at 50 - 72 ohm or so impedance, is a whole lot closer to the
center fed impedance of a "close to the ground" dipole.
> Makes a fair amount of sense, to use it for feedline, clear down to the
> rig, when the rig has a balanced output.. or to the balanced to
> unbalanced, 1 to 1 ratio apparatus. And with a stranded, larger than RG-58
> or RG-59 coax center, it won't have any additional I-R loss than that
> coax, and our HF freq. And of course, making the distinction that we are
> talking about a single band dipole... not a multiband, center fed with
> what ever the tx is dialed to balanced antenna.
>
> --... ...-- Dale - WC7S in Wy