AW: [Elecraft] PlugIn Balun for K2/Kat1 ATU

[Peter Zenker]

George,
the KAT 2 handles abt 8 to 800 Ohm as far as I know. The feed point
Impedance of a Lambda 1/2 Dipole is abt 72 Ohm, used on the next
harmonic I assume its higher then 800 Ohm. That=92s the reason for me to
use a step up balun. The impedance transformed to the ATU depends on
length of the feed line, and frequency. You can bring it up to either
higher or lower impedances. In my experience, it was very seldom, that
the impedance at the ATU side was less then 30 Ohm, this happened only
with extreme short antennas. ( With my ZM-2 I never ever needed the
extra capacitor at the input side which is needed, if you have extra low
impedance.)

BTW,=20
If I am outdoor with a twin wire feeder (my normal Antennas :-) I carry
with me an extra length of 3 Meter feeder line with 2 Banana jacks at
one side and 2 Banana plugs at the other side. If a given Antenna has a
"bad" impedance at the ATU end, I add this extra line and, bingo, its
easy to tune now.

I will think about adding a switch and will test it. Actually there is
definitely no place for such a swich, I have to use a bigger enclosure,
and I am not sure if I get the same excellent results if I use the
switch.
But I will try it.


73 de Peter,=A0 DL2FI
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DV Berlin DARC e.V.
German QRP Group DL-QRP-AG http://www.dl-qrp-ag.de
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> And, Peter, could you comment on the reasons for your choice of a 4:1
> balun? I note that the addition of a switch could readily change it to
a
> 1:1 current balun.