AT Measuring balun common mode impedance – #1 I gave an example of the use of a Rigexpert AA-600 to measure the common mode impedance of a current balun.
Above is a plot from that article. I cannot be sure what version of Antscope was used to create the graph, but it was no later than v4.2.57, as one of the ‘improvements’ of v4.2.62 and v4.2.63 was to reduce zooming of the Z scales to a maximum of 600Ω.
Above, the graph zoomed to the improved maximum of 600Ω. At this scale, you can also see one of the other defects of Antscope in that the graph is not properly windowed, eg X at the cursor is -1121Ω, not -600Ω as shown by the green plot line.
I did contact Rigexpert support regarding the disabled zoom but was summarily dismissed by Oleg with the advice to use the earlier versions.
So, if you want the convenience of zooming out to the extent available in v4.2.57, then you need to downgrade to it (note the old location for the cable data and ini files etc). I could not find disclosure of what changes were made in subsequent versions, so there is risk that an important fix or feature is lost in the quest to restore the old zoom capability.
The other option of course is to export the data and plot it in Excel or some other graphics package, but that denies the great utility of previewing the data immediately that a measurement is made and being able to conveniently and quickly redo the scan if changed parameters are needed.
In my experience, the software supplied with most ham grade analysers and VNAs is pretty shabby and lets the overall package down. Antscope is no exception.
To the proposition put to me that the AA-600 is not capable of measuring the common mode impedance of a broadband current balun (as described at Measuring balun common mode impedance – #1), I respond that it is capable of measuring R and X to several thousand ohms and of correctly measuring the sign of X, but the latest software (v4.2.63) has been changed to deny convenient and meaningful direct graphic presentation of the measured data and you need to export the data and use another tool for presentation and analysis.
One could obsess over the capacity to measure Z in the range 5,000 to 50,000Ω and the appropriateness of reflection measurement technique, but the key parameters for broadband baluns are not the maximum impedance components but the minimum impedance over the desired operating range and measurement to 5,000Ω is quite adequate for that task in most cases. Note that Rigexperts (or other analysers) with less ADC bits than the AA-600 (16) might be quite challenged for this application.