nanoVNA - Alligator Clip Leads vs. VNA Test Fixture Kit - Measuring Inductors & Capacitors

Does using a more formal test fixture with the nanoVNA result in better measurements when testing inductors and capacitors to confirm their nominal values?

0:00 Introduction
3:58 Full calibration of the nanoVNA
6:13 Hooking up the test fixture
6:37 Measuring the inductor value
8:40 Why measure at + and - 90 degrees on the smith chart?
10:40 Measuring the capacitor value
12:38 Testing the measurement accuracy
14:32 Building the parallel resonant circuit
15:10 Setting up the nanoVNA to measure the resonant frequency
16:29 Measuring the resonant frequency
18:34 Examining the results
20:29 Hooking up the alligator test leads and calibrating the nanoVNA
22:39 Measuring the inductor value using alligator leads
23:49 Measuring the capacitor value using alligator leads
24:56 Comparison of results and conclusion

VE6WGM (VE6WO)

[acestudioscouk-Ace-GACE]

As a beginner in electronics, I found this fascinating and was able to to follow due to your clear and relaxed presentation style. Thank-you.

[rfburns]

Very nice demo. I was about to do the same test. One thing I noticed, and it may be minor, is that you held onto the back allegator lead which may have induced some hand capacity in the measurement. Even though it was the black shielded allegator clip it still could have some effect.

[JimSky]

Seems like the test fixture should be used in the calibration of the VNA.

[danboy]

Just got my first nanoVNA and came across your video… great information and easy to follow. Thank you.

[intotheblue]

A lovely clear presentation style, showing your comparison project which is informative and very enjoyable, thank you.

[keyboarderror]

I soldered a couple of SMA connectors to Dupont pin headers for an easy way to use them with a breadboard. It works pretty well, and you can use the split sides of the board for through connections. If you don't have a dedicated test fixture handy.

[kapbo]

That was fantastic! Great explanation the whole way. I agree; for ham radio and electronics experiment stuff, the clip leads are just fine. I have a test fixture but always go to the clip leads .As long as you calibrate each and every time, you're good to go. 73 and Thanks

[enriquea.wembagher]

Gregg ...Excellent work and demostration !!!! Vy 73

[ernestb.]

Great experiments. And of course we would need a test fix for smd as well...

[TheSmokinApe]

Well done, I really enjoyed this video 👍

[DmitryAvsioukov]

When solving back for L you've actually solved it from calculated frequency, not measured one. No surprise you've got your 14.8uH back :)

[julianperry]

Hi Gregg, very useful video. How can one connect larger diameter items, like a coil made from 2mm dia wire, to the test board kit? Such a coil would seem to only be measurable using alligator clips. Is there some other connection option for the test board method? Thanks

[majedkharouf]

Nice video, one of a kind :)
If I have a parallel RLC circuit with a resonance frequency of ~300 MHz, is this board still suitable? Are there better alternatives for such high frequencies?

[MichaelPechner]

frm what I can tell the only pins connected to out si column 7 rowsc, d, e. B ut you connected the inductor to row A. i assume you modified your board?

[lemonkey]

What if the frequency of the application happens to be above the self-resonant frequency of the inductor or capacitor?

A challenge I’m facing is finding the correct capacitor and inductor to use in an LC match circuit given values solved for by SimNec (SimSmith). Particularly when winding my own coils for inductance and using variable capacitors.

I’ve been measuring the components by themselves AT the frequency of the application, but the results aren’t as good as expected and I’m starting to think it may be related to the self-resonant frequencies of the components.

The frequency in question is the 2m band.

Thanks for the idea to confirm the measures values using a parallel tank circuit. I’m going to try that today with my vna test board kit.

[JPEE]

I would have thought that the calibration for the alligator clip would be more accurate, because you calibrated it to the tip of those. With the test board, you did not calibrate it inline with calibration procedure- it was left out. That board could affect the capacitance and inductance, right?

[galileo_rs]

You are measuring the fixture and the DUT, calibrate using the fixture connected. When you adjusted the stimulus you forced the VNA to do interpolation, not that important in this case but generally a bad practice.

[IKXOO--Paolo]

The reason you find difference using the alligator clips cable probably is due his characteristic impedance, bnc connector included. Check starting from there: does it use a 75 ohm bnc version?

[BobMellor]

Thanks for this, very interesting, just subscribed 73 Bob

[ivolol]

I really don't see the point of your segment at 18:34. You essentially only re-did your same previous calculation backwards, except with a bit of rounding error stemming from initial truncation of the result. I speculate that maybe you got confused, and actually wanted to find the value of what L should be if inserting the measured tank frequency, 1.344Mhz, rather than the calculated, 1.358. Doing that, I got a calculated L of 15.11uH.

Otherwise, cool video on using nanovna to inspect component values and resonances. And I solved the above using the exact same calculator :)

Funny enough your alligator readings got 2000khz closer to the tank measured frequency.