[Elecraft] KAT100 with Ladder Line

[Don Wilhelm]

You are quite correct.  My favorite tuner of all is a link coupled 
balanced tuner, and it is L B Cebik's favorite too - low loss and can be 
configured to match just about anything - series tuning for low 
impedances or parallel for higher impedances.  I have built many over 
the years.  No balun required anywhere. If I were able to bring 
ladderline into the shack, I would have one of my old balanced tuners 
with the plug-in coils to match the transmitter to the ladderline - but 
I can't do that (don't ask!), so I use resonant antennas fed with coax 
and clean up any required additional tuning with a KAT100.

But, one must admit that the KAT100 does offer a lot of convenience to 
the operator, even though it has some drawbacks - it is not balanced, 
and for those who are fortunate enough to bring ladderline into the 
shack, it can be used with a balun.  It is a workable solution as long 
as some cautions are observed to minimize the loss.  One cannot defeat 
the laws of physics, but for those who must use an unbalanced tuner and 
a ladderline fed multiband antenna, the KAT100 followed by a balun may 
be an acceptable solution.  Adjust the feedline length so as to provide 
a decent feedpoint impedance at the balun without a lot of reactance, 
and use a current type balun (a voltage balun just will not work well in 
this application), and one can get on the air - it certainly is better 
than no antenna at all.

73,
Don W3FPR

Goody K3NG wrote:
> Using any balun with an unbalanced tuner to feed balanced line can be 
> bad news (your mileage may vary, standard disclaimers apply).  Under 
> highly reactive loads, a balun used like this can become quite lossy.  
> There's a couple articles in publications and on the Internet on this, 
> but Cebik's article is one that comes to mind ( 
> http://www.cebik.com/link/l-bal.html ).  It's better to run a real 
> balanced tuner like a Johnson Matchbox, the MFJ Balanced Line tuner, 
> or others, if you can.
>