Personally, I only care about a pure comparison test in as controlled
circumstances as possible. Any practical test like you describe will
have so many variables that it won't be useful for anything other than
as an anecdote. "Ground" is going to be wildly different depending upon
location. Propagation is highly variable for distant reports, and if
you instead use a nearby setup for reception, it will make a difference
which direction is it relative to the trailing counterpoise.
Besides, lots of people have already proven they can make contacts with
the scenario you describe, but nobody has a clue how efficient that
might be or not be.
73,
Dave AB7E
On 9/25/2022 12:30 PM, Julia Tuttle 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 <[email protected]> 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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