For anyone not familiar with them, they are a group that is dedicated to growing the knowledge of, and therefore use of CW.
For the course, we have an advisor and several of us learners who meet twice weekly and review our progress against their curriculum.
While I am just at the start of this journey, I cannot say enough good things about how this is organized and the time that is put in by those involved.
This week we ran through identifying our Instant Character Recognition weak points. It was instructive to see where I struggled, but it also confirmed my suspicions as well.
I’ll add more as I progress, but this is an amazing group and a beginning for me on getting from CW infancy to hopefully walking on my own.
Using a Rig Expert AA-35 Zoom and the antScope 2 software, I ran through a few scenarios that I’m posting here for my reference and yours.
The antenna was setup in my backyard in a vertical configuration. I unspooled exactly 25 feet of counterpoise per the manual (marked with electrical tape for repeatability), laying it on the ground.
The entire length of the included coax was also unrolled and laid out on the ground. I did note initial higher SWR readings with it coiled and with a shorter length between the antenna and the analyzer.
Let’s start with a full range reading. This is the end to end range that the AA-25 Zoom can handle, which is 60kHz to 35MHz.
The vertical bands represent the US amateur radio bands from 160m – 10m
We can then run through each band, one by one, zooming in on the SWR ranges that the analyzer reports. Note the wide portion of each band that is covered by the SWR regardless of it being >= 1.5. We do not see large dips that start and end with the band edges.
160m
The overlapping colors represent multiple runs that I did on this band, playing with the placement of the counterpoise wire
80m
40m
30m
20m
17m
15m
12m
10m
Confusion
Upon getting the band by band results, I started scratching my head because the SWR readings that I was getting was different than what Chameleon reports in their user manual.
In some cases better, in others worse.
I decided to then run the AA-35 Zoom against my Hustler 4BTV Vertical antenna which I have for my permanent antenna installation at home.
Hustler 4BTV analysis for comparison
Everything lines up exactly like I expected for the 40/20/15/10 meter portions, so I am chalking up my CHA MPAS Lite readings to one of two things; environmental factors such as location, etc., or difference in meters being used from Chameleon and myself.
In either case, Chameleon does state in their user manual that:
The CHA MPAS Lite requires a wide range antenna tuner or coupler on some bands…
Page 3 of User Manual
In other words, this is not a resonant dipole that you hang in a tree and then go – it is a toolbox sort of antenna that performs quite well across multiple amateur bands, but requires some tuning depending on what band you’re using.
Conclusion
For reference, here is what they published for SWRs in a vertical configuration vs what I got, with green and red representing better or worse than advertised respectively:
Frequency
Chameleon’s SWR
KD0HBU’s SWR
1.9
4.5
3.7
3.7
3.3
2.9
7.1
2.0
2.8
10.1
1.8
2.8
14.1
1.7
2.1
18.1
1.2
1.5
21.1
1.2
1.5
24.9
1.6
2.2
28.5
2.0
2.6
There are a lot of variables that can affect an antenna and this is just a snapshot of one deployment in one area using one analyzer. I do intend to try the same deployment with my nano-VNA to see how the two compare.
If anyone knows what I should try different to improve on the above, please let me know in the comments.
kd0hbu.com 