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Sunday, 3 May 2020

NanoVNA - Test fixtures for measuring SMD's Summary

Well, I'm really impressed. I never expected such a low cost instrument to perform so well. Granted, as frequency increases you get some odd results, but nothing that detracts from this piece of test gear. Perhaps I'll buy a second unit and dedicate it to SMD measurements. Then I could recall calibrations like 0-30MHz, 0-100MHz, 0-300MHz and 0-900MHz with ease.

I can also recommend the test fixture I made. Simply a SMA connector onto a PCB. The track and pads allow for calibration ie

    Short - bridge the track with a piece of copper tape, perhaps like that shown in the picture which
                was there to short out some imperfections,

    Open - with nothing in place

    Load - a 50 ohm resistor bridging the gap. Could be two 100 ohm resistors soldered together but
                you can buy or recover 50R chip resistors. 

Once calibrated same your settings and if you need to recover a part or measure somehting it becomes very easy. It never appeared to be introducing errors which is a credit to the people behind the NanoVNA.

A few more pics just to whet your appetite to replicate this:

The 22nH Inductor



0201 12nH Inductor

Measured with ease

1 47nH
2 56nH
3 6.8pF
4 200 ohms
5 1.5pF
6 0 ohms

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