[Elecraft] 135ft flat-top with K2, KAT2, BL2, and 450 ohm feedline

[Don Wilhelm]

Zac,

Why guess?

You can find the antenna feedpoint impedance for various bands on L B
Cebik's website (at least it used to be there) www.cebik.com .
Armed with that information along with the known length of your feedline,
use TLW which you can download from the ARRL website
http://www.arrl.org/notes/9043/TLW3B.zip and feed the information into TLW
to find your shack end impedance for each band of interest.  A bit of cut
'n' try with TLW can find you the best compromise feedline length to ues
with your antenna.

73,
Don W3FPR


> -----Original Message-----
>
>     I'm sorry but I need to add this before Zac Brown does something
> real stupid. When using 450 ohm feed line you must use this EXACT
> length. The exact length is that which goes from the antenna to the
> balun in your shack.
>
>     Any talk about matching the 450 ohms is not correct. The feed line
> runs with a very high SWR and since it is low loss there is just a tiny
> loss. It will correct to a 1:1 SWR between your tuner and the radio.
>
>     And about the balun. Seems if you have a 4:1 or 1:1 to choose from I
> would choose the 1:1 because it does a better job of keeping the current
> balanced in the balanced feed line.
>
>     This is pretty complex stuff but you Zac do not need to do the math.
> Just put it up and use it. I have been using it for 8 years now. Had to
> get feed line. A hail storm just beat up my feed line :-)
>
>     I have done the math. It takes several Smith Charts to plot the
> current through the system.
>
> 73 Karl K5DI
>
>
>
>
> Zac Brown wrote:
> > So what's the best way to add some more line to the middle of my
> > feedline?  Is there a technique for joining two pieces of 450 ohm
> > ladder line that doesn't create an imbalance in the line?  Can I just
> > leave one "leg" straight and then wrap the corresponding "leg" (on the
> > other piece) other around it, then solder them together?  Or should I
> > just leave both legs straight and then solder them together?  Or how
> > about using those twist locks that you use for wiring up lights?
> >
> > This is probably a silly question, but I took great care to route the
> > line away from anything that would imbalance it, and would hate to
> > mess that up now.  This is my first experience with balanced line :)
> >
> > Thanks,
> >
> > Zac
> > KD5IEF
> > K2# 4907
>