[Elecraft] Feeding a Random length wire with the KAT2 ATU

Thu Apr 3 22:34:10 2003

I was surprised at the range that the KAT2 ATU had. Actually since the
power levels are low, there is a large range that can be had with
physically small components.

I fed an 80 meter inverted vee out 200 feet of coax directly from the
K2. The KAT2 was able to match it 1.8:1 or better on ALL BANDS. Sure
the long coax run helped some.

The worst end-fed length to match directly would be one close to a
multiple of a half wave. The region around a half wave mult is
extremely high reactance and/or resistance. Without going into a huge
list, 38' should work for 40 and up, except possibly not on 12 meters.

You should feed this against some kind of ground, which could be as
minimal as a 38' insulated wire laid out along the ground, in a
direction opposite the predominant direction of the elevated wire. 78'
is needed for 80-20 meters, some possible issues with 17 and 12.

For the lowest band only, the best arrangement for a wire is to put up
something 5/16 to 7/16 wavelength, and let the KAT2 tune out the
reactance. The ground system is going to be such a loss issue that the
longer the wire the better. This is balanced by the need to avoid 1/2
wave.

You could determine experimentally just how close you can get to 1/2
wave and still have the KAT2 match it. This setting will also be the
point where the ground current sink resistance causes the least loss
in the antenna SYSTEM.

Good luck,
Guy K2AV

----- Original Message -----
From: "Leonard, David" <[email protected]>
To: <[email protected]>
Sent: Wednesday, April 02, 2003 11:11 AM
Subject: [Elecraft] Feeding a Random length wire with the KAT2 ATU

> Hey Fellow K2ers
>
> I am portable down here in the "wilds" of Tennessee. I have a
Buddipole that
> covers 40 meters and higher bands.
> I would like to put up a random length wire antenna to see if 80
meters
> might work better to sked back into Chicago at night.
>
> Does anybody have experience with random wire antennas and the KAT2?
>
> Any special "tricks"?
>
> I am in an apartment on the ground floor and all we have around here
are
> "saplings" (about 12' tall 8-(
>
> Any suggestions? (No I can't move 8-)
>
> Tnx in Advance
>
> de Dave K9FZJ (Formerly WB9SOG)
>
>
>
*********************************************************************
> This message and any attachments are solely for the intended
recipient. If you are not the intended recipient, disclosure, copying,
use or distribution of the information included in this message is
prohibited -- Please immediately and permanently delete.
>
>
>
> --- StripMime Report -- processed MIME parts ---
> multipart/alternative
>   text/plain (text body -- kept)
>   text/html
> The reason this message is shown is because the post was in HTML
> or had an attachment.  Attachments are not allowed.  To learn how
> to post in Plain-Text go to: http://www.expita.com/nomime.html  ---
> _______________________________________________
> Elecraft mailing list: [email protected]
> You must be a list member to post to the list.
> Postings must be plain text (no HTML or attachments).
> See: http://mailman.qth.net/mailman/listinfo/elecraft
> Elecraft Web Page: http://www.elecraft.com