The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50.
I purchased what appears to be a ‘genuine’ nanoVNA-H and it has firmware NanoVNA-H_20191018.dfu installed. During checkout of the delivered device, an issue became evident, an issue worth describing in its own article.
Glitches on the displayed data are occasional, but hardly rare, and are a concern.
The nanoVNA was OSL calibrated (is for reflection only) from 1 to 500MHz and the cal save in C4.
On repeated scans of the SC used for the cal, there are obvious occasional glitches evident on various PC clients.
Above is nanovnasharp v1.03. An expanded scale shows the observation, an occasional single measurement, always with a downwards glitch of |S11|dB of variable magnitude, but usually less than a couple of dB. Continue reading nanoVNA-H – occasional glitches in measured data
Last update: 2nd February, 2020, 7:11 AM
At Series match for a half wave dipole I mentioned that RG6/U may have a copper clad steel (CCS) centre conductor, and may have significantly more loss at HF than expected based on datasheets and calculators.
Above is a comparison of matched line loss based on measurement of a length of RG6/U Quad Shield CCS cable and prediction from Simsmith of Belden 8215 (also CCS). The ripple is due to measurement system error. Continue reading RG6/U with CCS centre conductor at HF
Last update: 8th June, 2020, 7:14 AM
An online poster was demonstrating the effect of varying line length on a half wave dipole on VSWR(50) and by mistake configured the line be of of Zo=75Ω.
He asked the question
In the general case, if you are trying to match 50 Ohms, would you be better off feeding a normal backyard dipole with 75 Ohm coax if you are willing to prune it to a specific length after the fact?
Continue reading Series match for a half wave dipole
Last update: 7th November, 2019, 11:48 AM