[Elecraft] Baluns for KAT1

[Ron D' Eau Claire]

I'll second what Don said and add that it's not too hard to tell what you
have in the way of an impedance extreme at the end of your feeders where
they connect to a balun if you aren't sure... at least well enough to tell
whether or not you are really pushing the balun.

If the ATU acts like it has to retune constantly you can suspect you have a
high impedance at the rig end. Take a small (NE-51 type) neon bulb and hold
the leads in your fingers and place the glass bulb against the connection at
the end of your twin lead where it enters the balun. If the bulb lights when
you key the rig, you know that you have a fairly high impedance at that
point. (The bulb is lighting from the high r-f voltages that accompany a
high-impedance point).

You can check for current by putting small flashlight bulbs in series with
the feeders and seeing if they light, and if they light evenly. An even
lighting of similar bulbs indicates that your feedline is probably pretty
well balanced (and the balun is doing its job). If you are near a current
loop, only a watt or two will be enough to make common flashlight bulbs burn
brightly. IF you have a voltage loop at the balun, full 10 or 15 watts is
probably not enough to make the bulbs glow at all. I use some small screw-in
sockets from Radio Shack with banana plugs and jacks soldered to them so
they can be inserted easily and the bulbs can be changed easily. It's easy
to burn them out!

A high current point at the balun is not usually a problem, especially at
the power levels a K2 generates. If you have a voltage peak there and the
tuning seems 'touchy' you can try adding a few feet of feedline. Don't bunch
up open wire or twinlead - lay it out run it somewhere so it is not all
piled up on top of itself.

Of course, if things seem to tune nicely you don't need to add anything.
Just enjoy!

Ron AC7AC
K2 # 1289