Saturday, September 28, 2019

nanoVNA vs. Keysight N9913A at HF

I made a few side-by-side measurements today comparing the $50 nanoVNA with a Keysight N9913A unit at my work QTH. These comparisons covered 400 kHz to 30 MHz using a Pacific Antenna 41dB step attenuator (built from a kit) and RTL SDR's AM-broadcast band reject filter.

Although my purpose was not so much to test the attenuator or filter, I found both of them to be excellent performers, especially given their price.



The main purpose of the comparison was to see if I can trust the data from the inexpensive nanoVNA. It gives a pretty picture which is completely meaningless if the presentation is not valid.

Prior to all measurements I calibrated each VNA according to instructions for that particular unit. Both were allowed to warm up for an hour before the first calibration.

The nanoVNA was operated via my PC with NanoVNA Saver from Rune Broberg 5Q5R and was calibrated via the software (the nanoVNA may be calibrated stand-alone as well).

I am quite happy with the results of the test. They show that - at least at HF frequencies - the small nanoVNA is dead-on accurate.

Tomorrow I'll be comparing the two at higher frequencies: a 2/440 antenna and a 1.03 GHz band-pass filter. The upper limit for the nanoVNA is 900 MHz (the Keysight's is 4 GHz) so it'll make for an interesting test to see if the nanoVNA's accuracy deteriorates at higher frequencies.

The photos and graphs of today's HF tests speak for themselves:
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The Bypass switch accounts for .25dB to .5dB of attenuation with none dialed in via the switches
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And now on to the band-reject filter:



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In summary:


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2 comments:

Unknown said...

Thanks for the comparison. Good to know. Measuring a second instance of the RTL BCB filter here I get same result. Hopefully now I can get all of the filters projects tuned properly.

John AE5X said...

Yep, it's a good use for the nano. I'm building a little jig that I can plug all of my LP filters from QRP Labs (G0UPL) into and measure.