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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