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

[Gerry leary]

I have used my AX2 both ways, and I have never found it to be advantageous to use that antenna without a counterpoise.

Gerry Leary Wb6ivf

On Sep 25, 2022, at 1:31 PM, Julia Tuttle <julia at juliatuttle.net> wrote:

Hi Dave,

I think that's a proper comparison in a physics sense, but I don't think it
fully represents how the AX1 is deployed in practice.

I would run both an ideal scenario -- the one you described -- amd a
practical scenario -- something like a KX3 + internal batteries on a picnic
table, AX1 on the bipod, and the counterpoise trailing down to and across
the ground.

73,

Julie

On Sun, Sep 25, 2022, 15:19 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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