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

[Gerry leary]

Do you think you would get the same results on receive as you would on transmit? I have found in my playing around that yes and 10 is likely a X one or a X to work best if the counterpoise is also hanging vertically below it, but I have never ever ever been in a situation where the antenna worked as well without a counterpoise.

Gerry Leary Wb6ivf

On Sep 25, 2022, at 1:19 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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