Posted by
Tim McDonough N9PUZ on
Oct 10, 2019; 6:59pm
URL: http://elecraft.85.s1.nabble.com/KX2-Antenna-Curiosity-tp7655612p7655618.html
If you are talking about a single band dipole then any half wave dipole cut
to the standard formula and fed with good quality coax should work well. If
you want a "multi band" dipole then I would recommend cutting it for the
lowest frequency you plan to operate and feeding it with balanced line.
Even the best coax can have a lot of loss under high SWR conditions
(between your tuner and the antenna feedpoint) whereas even at 1 10:1 SWR
balanced line does not have much loss. The radiation pattern of a multi
band configuration can vary a lot from band to band.
The end fed wire you describe is not specific to the KX2. You typically
want the longest wire possible that is NOT a half wavelength or even
multiple on any band you want to operate. The main reason for this is when
a wire is a half wave or an even multiple the impedance at the end of the
wire can be very high and it is more difficult for most tuners to obtain a
match there. By it NOT being a half wave, the impedance is lower and a wide
range tuner like the one in your KX2 can match it more easily and present
the proper impedance to the radio.
Here is an article that suggests good lengths for a "random wire" antenna.
The lengths aren't really very random, they are specifically chosen to be
easier to match. At 58.5 feet you arrived at one of the good lengths.
<
https://udel.edu/~mm/ham/randomWire/>
Tim N9PUZ
On Thu, Oct 10, 2019 at 11:03 AM Joseph Shuman via Elecraft <
[hidden email]> wrote:
> I have had my KX2 with the ATU for about 10 months and operate on 40m QRP
> SSB from various locations. Experimenting with different antennas I have
> experienced best results with a 58.5’ wire tossed about 25’ up a tree with
> a 16.5’ counterpoise. I ran the same length wire from my house to the
> workshop, grounded the shield side of the cable, and have seen similar
> results to the field setup.
>
> Is there some engineering/design factor of the KX2 for this type of
> antenna setup? I am planning to setup a Dipole at home, but as a newbie am
> wondering if the “ideal” Ham Dipole can be expected to improve performance.
>
> Keeping Watch-
> shu
>
> Joe Shuman
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