[Elecraft] Baluns and 450 ohm line

[Charles Greene]

At 11:15 AM 6/4/2002 -0700, Ron D'Eau Claire wrote:
>Bill wrote:
>
> > Uh, Ron, I'd like to point out that at HF, the vast majority of the loss
> > in open wire or coaxial lines is resistive in nature.

I made have some home made transmission line using #26 silver plated 
wire.  It's characteristic impedance is about 200 ohms.  We planned to use 
37' for field day.  KC1SD calculated that it had a RF resistance (different 
from DC resistance due to skin effect) of 5 ohms for 74' at 7 Mhz.  He said 
he used Terman's.  That's not much loss, but the dielectric losses are low 
too, so it is possible for that piece of transmission line, the ohmic 
losses might be more than the dielectric losses.  Not so for coax where the 
wires are larger giving less RF resistance and more dielectric 
loss.  Anyway, the RF resistance loss can be estimated and subtracted from 
the total loss which is listed in the specifications for a particular coax.


73, Chas, W1CG