http://elecraft.85.s1.nabble.com/KX1-We-need-to-develop-the-ideal-antenna-tp6366906p6360601.html
I've had seemingly good results with my KX1 on 20, 30, and 40 just using the
25 ft wire thrown into a tree and a 16 ft counterpoise along the ground. The
KXAT1 found useable matches every time. It seems like I remember doing OK on
> Bob,
>
> Actually, a properly functioning KX1 has an MDS of better than -130 dBm,
> so it actually is a sensitive receiver.
>
> Some like the Carolina Windom, but I don't like any unbalanced antennas,
> and have a high preference for center fed antennas, they are easier to
> tame, and if the feedline leaves the antenna at right angles from the
> center, seldom do "RF-in-the-shack" problems emerge.
>
> The KXAT1 has a more limited range on 80 meters than the other bands
> just because the total inductance and capacitance is limited - only 3
> choices of each.
>
> I would suggest a trap antenna with traps for 40 and 20 meters. Feed it
> with balanced feedline cut a half wavelength (or multiple) on 80 meters
> - the tuner should be able to match it on 30 meters and the half
> wavelength of feedline on 80 meters should present a feedpoint impedance
> close to that at the antenna center (50 to 75 ohms) for 80, 40, and 20
> (assuming the traps are used).
> I have not actually built such an antenna, but the theory says it should
> work just fine. Keep the balanced feedline supported along its entire
> length and don't forget that there is a velocity factor to consider when
> determining a half wavelength - if you cannot do that, add a trap for 30
> meters and feed it with any length of coax. Coaxial traps are not
> difficult to build, and for QRP use, can even use RG174 on a piece of
> 1/2 inch PVC for a form. Doug DeMaw (SK) W1FB had information on
> building traps like that in QST a very long time ago (try in the
> 1980s). Also see the W1FB Antenna Notebook and/or the article in QST
> for Decenber 1984 page 37 by N4UU. Gary o'Neil N3GO also has some good
> information about coaxial traps on the web (use Google).
>
> I realize that a 135 foot long antenna is not "easy to deploy", so I
> would suggest an alternative - build a coax fed trap antenna for 40, 30
> and 20 meters (traps for 30 and 20), and carry along 2 33 foot lengths
> of wire - insulators on one end and an alligator clip on the other -
> when you want to operate 80 meters, add the wires to each end of the
> radiator. You could carry that concept a bit further, and build the
> antenna for 20 meters with no traps and then add a set wires for use on
> 30 meters, another set of wires for 40, and yet another set for 80.
> clip on the wires for whichever band you want to operate.
>
> That is my nickel's worth.
>
> 73,
> Don W3FPR
>
> On 5/13/2011 1:31 PM, AB5N wrote:
> > Hi Guys-
> >
> > Well, I'm in week two of enjoyment with my new KX-1. I did have a few
> > problems in assembling, but
> > that is history.
> >
> > This little rig has a simple receiver which has only half the sensitivity
> of
> > a usual radio. As well, we are dealing
> > with 3-4 watts TX out max. We have to have an excellent antenna. I've
> tried
> > the suggested 25 ft. long wire
> > with radials. Ah, it's not good enough. I even got some strange
> RX-feedback
> > internally at some frequencies using it. I believe the criteria for an
> > excellent antenna will be as follows:
> >
> > 1. Will match up well using the internal tuner on all four bands.
> >
> > 2. Has enough metal in the air to provide adequate microvolts to the RX -
> to
> > make it function well without
> > being overloaded.
> >
> > 3. Provides some gain - or at least a clean predictable pattern
> >
> > 4. Is light, compact and easy to deploy.
> >
> > My inkling is that a normal Carolina Windom may be the thing. I'll work
> on
> > developing a micro-QRP version.
> >
> > What doesn't work?
> >
> > Classic G5RV (102 Ft) - will not load on any band with tuner.
> > Offset-Zepp fed with Coax (75'x25')
> >
> > What say guys? Anybody have superb luck with an antenna yet?
> >
> > Bob-AB5N
> >
> ______________________________________________________________
> Elecraft mailing list
> Home:
http://mailman.qth.net/mailman/listinfo/elecraft> Help:
http://mailman.qth.net/mmfaq.htm> Post: mailto:
[hidden email]
>
> This list hosted by:
http://www.qsl.net> Please help support this email list:
http://www.qsl.net/donate.html>