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

[Bill Mader]

Dave is getting closer to a valid test.  However, testing on two different
days (rig and antenna inventory) is not quite useful for obvious reasons,
mostly propagation conditions.

A better method is to use a "standard" dipole and two WSPR transmitters;
one on the dipole and another on the two different AX1 configurations.
Then, the numbers become comparisons against the "standard" dipole.  the
point is to spend 24 hours comparing one configuration against the dipole
and the next day the second configuration against the dipole.

Putting the results in a spreadsheet quickly makes antenna configurations'
difference apparent.  I have done something similar using the RBN, two
antennas, and two nearby frequencies on the same band.  This method
effectively identified which antenna was preferred in different directions
and distances.  Even so, the differences could change briefly at any time
so being able to switch antennas instantly was extremely helpful.

Anecdotes, even comparing configurations from one day to the next are not
very helpful unless done over many days.  WSPR is an excellent tool for
antenna and propagation study.  A pair of WSPRLite transmitters provide
accurate, useful data whereas "I worked..." can be interesting, but not
very useful although it is extremely popular.

73, Bill, K8TE


Date: Sun, 25 Sep 2022 12:19:03 -0700
From: David Gilbert <ab7echo at gmail.com>
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] AX-1 -- with and without counterpoise
Message-ID: <e217c2a2-fb72-ad8a-e4e2-e415914f1924 at gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed


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



73, Bill Mader, K8TE
ARRL New Mexico Section Manager
*ARRL - The national association for Amateur Radio**™*
Secretary/Treasurer and Past President, Albuquerque DX Association
W6H NM Coordinator, Route 66 On-the-Air 8-17 Sep 2023
New Mexico QSO Party 8 Apr 2023
Duke City Hamfest Chairman www.dukecityhamfest.org 15-17 Sep 2023