[Elecraft] AX-1 -- with and without counterpoise

[Richard Hill]

It would be interesting to see the results of a fully double blind
scientifically reproducible test done with traceable engineering quality
test equipment on a closed pedestrian mobile track.

NU6T

On Sun, Sep 25, 2022, 12:19 PM David Gilbert <ab7echo at gmail.com> wrote:

>
> To be a proper comparison, the AX1 needs to be out it the clear away
> from anything else, preferable at a height that allows the counterpoise
> to be hanging straight down with the end maybe a foot or two off the
> ground.  Measurements should be with the AX1 at the same height above
> the ground without and without the counterpoise. Ideally a KX2 or
> similar rig should used, be battery powered (with very short leads if
> external), no coax, and no body contact to the source of RF.  Signal
> reports should be in microvolts ... the number of contacts isn't really
> useful and neither is SNR if the readings are taken over a lengthy
> period of time.
>
> If I can get my hands on an AX1, I plan to either climb a tree or set up
> a tall fiberglass step ladder for the AX1 as far away line of sight from
> my home as practical.  I'd use my KX2 for the signal source, using the
> Tune function to put out RF without touching the KX2.  Near my home I'd
> set up the portable vertical antenna I described in an earlier post, and
> feed that to my K3 set to read microvolts.  I'd operate the AX1 (with
> and without counterpoise wire) and any other antenna for comparison, and
> have a friend record the microvolts from the K3 as a blind test.
>
> I would use the tuner in the KX2 to simulate actual use, but that would
> of course introduce a variable for possibly different amounts of loss in
> the tuner depending upon the load.  I don't see a good way to avoid that.
>
> 73,
> Dave   AB7E
>
>
>
> On 9/25/2022 7:06 AM, Ron Gruner wrote:
> > I've just run two tests of my WSPR/AX-1 set-up with and without a
> > counterpoise. Each test ran 24 hours over the last couple of days. Here
> are
> > the results:
> >
> >                                                      COUNTERPOISE?
> >                                YES       NO
> >                            -------  -------
> > Total Contacts                152      129
> > Maximum Distance (km)      15,720   17,276
> > Median Distance             2,137    1,823
> > Median SpotQ                  446      398
> >
> > Where SpotQ = Kilometers / [(2 Watts x (SNR in DB + 36))/36) ]
> >
> > The WSPR circuit's ground and SMA connectors are apparently providing
> > enough of a counterpoise to propagate a respectable signal.
> >
> > Here's a close-up of the rig with no counterpoise:
> > https://gruner.com/k4rhg/wspr_ax-1_nocounterpoise.png
> >
> > 73,
> > Ron Gruner
> > K4RHG
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