[Elecraft] Random Wire???

[Mychael Morohovich AA3WF]

Hi, David-

A random wire is any non resonant length of wire that you choose to use.
Generally, it is helpful to shoot for a length at least 1/2 wl of the lowest
frequency of desired operation. The 35' wire you suggested would be a little
more than a 1/2 wl on the 20 meter band, and a little more than a full wl on
the 10 meter band.

Try to avoid odd multiples of 1/4 wl as they will result in reactance (low
impedance) that will be tough to tune out, or "match".

The method I use to attach my end fed wire to the rig is a male banana
connector to the center on the K2's BNC connector, the other end of the
lead-in terminated with another male banana connector attached to a jack
installed in my window sill. I have another jack leading to a
counterpoise/ground (more on that in a moment), and another pair that leads
to a loop fed with ladder line. Banana jacks work well.

There is another consideration when working with an EFW. In order to keep
the rig at RF ground, it is useful to arrange counterpoises equal to 1/4 wl,
preferable slightly shorter if I recall correctly, on the bands that you
will be using, attached to a common point on the K2's chassis. They can all
be attached at once, though it is best to fan out their ends somewhat as
they could tend to detune one another. Also, while it is not so important a
consideration at QRP levels, generally it is best to keep the ends of the
counterpoise wires up and out of the way and/or taped as considerable
voltage could develop here while they are in use. In lieu of this octopus
arrangement, I use an artificial ground by MFJ as a simple matching device
for my single counterpoise.

Do you need a tuner? I would be surprised if you could easily come up with a
good EFW arrangement that would not require one, particularly if you desire
multi-band operation. Maybe someone else can help with this part of your
question.

Hope that this helps,

Mychael AA3WF
K2# 1025
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 I have my K2 all built and ready to go.  Now the hard part, I have to
figure a way to run an antenna. David, KG6MTI