[Elecraft] K2 external auto ATU

[Tony Estep]

Larry, I have had the same setup at two different QTHs. With some wrangling,
you can get the RF under control.

The place to put the balun is right at the window. Run coax from the balun
to the transceiver, and put a line isolator (available from
http://www.radioworks.com/) or some other version of choke, close to the 4:1
balun.

Make a counterpoise system. Ideally, you might have one wire of 1/4
wavelength for each band that you operate, but if you can't do that, at
least use several wires of different lengths. Tie them together at the shack
end and connect them to the ground side of the balun. If you model the whole
setup in EZNEC, you find that the least pattern distortion occurs if they
run under the antenna, although of course this may not be practical.

It helps if you have some sort of antenna analyzer, because the SWR and
reactance presented at the output of the balun will vary as you tweak your
counterpoise. But the end result is worth it.

With experimentation, you should be able to get the RF in the shack down to
where it's  unnoticeable. This setup sounds iffy, but I'm coming up on 300
countries with exactly what you describe.

Good luck!
Tony KT0NY




On Tue, Feb 1, 2011 at 12:11 PM, Larry Dodson <larrydod at googlemail.com>wrote:

> Advice/experience will be appreciated.
>
> I have an upstairs shack (ugh) with much RF.  Tried to earth without much
> luck.  Should use a balanced antenna, but.
>
> I have a windom antenna cut to 20%x80%, overall length 136 feet; used for
> 80-thru-10 meters. It is fed with vertical twin lead for approximately 20
> feet to a 4:1 balum and from there with coaxial to my rig. Whole antenna is
> 30 feet above the ground.
>
> Now my question.  I am using a K2, and have built a KPA100 and KAT100 in
> separate enclosure.  I would like to move the KPA100 and KAT100 in separate
> enclosure to the twin lead from antenna and use as an external auto ATU,
> then coaxial to shack, the distance being approximately 30 feet from the
> twin lead. I can locate external auto ATU inside of garage.
>
> What would be the problems? RF connection from K2 for 30 feet; control
> cable
> from K2 for 30 feet (maximum distance ?); 12v power?
>
> Thanks in advance -
> Larry (G0IKE) k2 - 2424
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