开云体育

Version 3



--
VE6WGM

For those of you who didn’t like my first two attempts at this video.. I think I’ve done a much better job on this one of explaining why I take my readings at 90 degrees phase angle on the smith chart

:-)

--
VE6WGM

Thank you for these videos.

Gregg,

I really appreciate your videos but I am old school and like stuff in writing. Would you have this procedure documented? Nothing fancy but just a short synopsis of
theory
settings
calibration
inductance measurement
shunt configuration accuracy reference
capacitance measurement

Thanks,

Mike N2MS

References were given as convenient clickable links in the description below the YouTube video.

--
VE6WGM

Hi Mike

Here is a brief textual overview of what I shared in the video..

To measure an inductor or capacitor, use a shunt configuration (basically attach the component to your nanoVNA using “alligator leads” so as to be able to make S11 measurements... hahaha! Oh yeah, I said that! Sorry RF Engineers.) Measure the capacitive or inductive reactance at a frequency where the reactance of the component is equal to the characteristic impedance of the system you are using to measure the inductor or capacitor (most likely 50 ohms). This will correlate to a phase angle of 90 degrees as measured by the VNA (positive for an inductor, and negative for a capacitor).

This strategy places the impedance being measured within the nanoVNA’s abilities to measure accurately, and ensures that the measurement is performed well below the self resonant frequency of the component. You’ll get correct results so as to be able to label an unknown inductor or to verify the value of a capacitor.

Where the use of such ‘crude’ test fixture will break down is if you happen to be measuring components that require a relatively high frequency in order for the reactance to be 50 ohms... in that case, the high frequency unfriendly alligator leads will need to be replaced with a proper test fixture.

--
VE6WGM

Was just over reading Roger’s excellent thread on using a VNA to examine discrete components. I figured I should be clear with everyone that the method I presented below is not and was never intended to be used for higher frequency work. If you’re trying to determine device behaviour at higher frequencies, perhaps for an RF project you might be working on, the method of measuring inductors and capacitors that I presented in the video linked below is not suitable. The intent is to give people a simple way to quickly measure inductor and capacitor values at lower frequencies so as to simply discover or verify the basic component values. Using alligator clips at higher frequencies is not going to give very good results, so if you’re wanting to characterize a component at higher frequencies then you would be well advised to go take a peek at Roger’s thread here: /g/nanovna-users/topic/pitfalls_of_measuring/80744049?p=

--
VE6WGM