I recently acquired a FA-VA5 antenna analyser.
Whilst preparing A first test of the FA-VA5 antenna analyser, issues were noticed with the user interface design / implementation.
This article started off as a video demonstration of measuring the Matched Line Loss (MLL) of a 6m length of old / budget grade RG58CU for comparison with the datasheet.
Using the instrument was such a frustration due to the user interface design / implementation, but more time was devoted to trying to understand it and experimenting with button press timing etc… but I must admit, to no avail. I persevered and made the measurements which are reported here, the matter of the interface issues will be dealt with separately.
So, the interpolated datasheet MLL for quality cable, Belden 8262 (RG58C/U), is 0.319dB.
The measurement technique is the measure the ReturnLoss of the DUT with o/c and s/c terminations, and estimate MLL=(RLo+RLs)/4.
Above, the o/c test.
Excuse the pics, there is a means of saving a screen shot in the FA-VA5, but I have not found a way of uploading them to a computer.
Above, the s/c test.
The astute reader will note that they are not equal, and a fairly good approximation of MLL is given by MLL=(RLo+RLs)/4=0.43dB, which is a little worse than specification of 0.32dB.
More on the method at On Witt’s calculation of Matched Line Loss from Return Loss.
As a reality check, measurements were performed with the AA-600 which yielded a result of MLL=0.4dB.
Conclusions
So the cable is poorer than spec, but not so bad as to be unusable.
The matter of the clumsy / unproductive user interface will be explored more at a later time.
Update: I find that the FA-VA5 was shipped with software that was superseded 8 weeks ago. Updating it invalidates all of the SOL calibrations I have done, wasting more than an hour’s work and about four hours of checkout needs to be redone.
The the defects apparent in the user interface, there might well be more updates, so be smarter that me, check for updates as they are shipped with stale firmware by my experience.
No, V1.08 does not address any of my identified issues, but hopefully it fixes some I had not tripped over yet.