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Once you have calibrated you setup at the measurement plane including any
fixtures, the following may help you (I've got the VNA in front of me as I
write so I'll go through the steps). To measure inductors and capacitors
you need only do the OSL cal. There is no need to do the isolation and
through cals. It is best in measuring capacitors and inductors (and other
passive components) to cal. over the frequency(ies) of interest. If your
frequency range is wide, do several cals bracketting your center frequency
of interest. I'll use the native VNA with no PC or Saver, just the
stand-alone VNA.

1) Tap the VNA screen and tap "DISPLAY".
2) Then tap "FORMAT".
3) Then tap "SMITH".
4) Then tap "BACK" twice.
5) Then tap "MARKER".
6) Tap "SELECT MARKER".
7) Select (tap) MARKER 1". I usually turn off all other markers at this
point.
8) Tap the screen to eliminate the right-hand "choice bar".
9) With your finger or styles, move the marker to the desired frequency.
10) Note the numerals in the upper left of the VNA display. The default
for this expression is impedance in R ± jX. In my case, I'm using a 130 pF
dip mica and sweeping from 7.00 to 7.30 MHz. Tthe upper left reads for
this case reads "CH0 1.0FS 0.924Ω 128pF" The 0.924Ω represents the
resistive component of my dip mica while the 128pF represents the actual
value of my dip mica at the frequency at which the cursor is set. That's
what you are after.

Again, the area above the central horizontal line on the Smith Chart is
inductive reactance. The area below the central horizontal line on the
Smith Chart is capacitive reactance. ONLY the central horizontal line
represents pure resistance with no reactive component.

The procedure presented in the Greg Messenger's video for measuring
capacitors and inductors is also sound. Personally, I prefer the Smith
Chart method. However, his cautions are valid for either method.

Hope this helps?

Dave - W?LEV



1)

On Sat, Apr 19, 2025 at 7:31?PM Phil Brown via groups.io <zapel406=
[email protected]> wrote:

Hi Dean and everyone who gave an answer firstly thank you. Yes I am using
Nano Saver on my laptop, yes I am aware of how to calibrate and the
importance of measuring at the plane, yes I have made jigs and am aware of
stray inductance and capacitance. Greg Messenger's videos seem to me to be
the best way of using the nano vna to determine values but I don't seem to
be able to replicate his menu settings and that is why I asked is Ver
1.2.27 different from earlier versions. All the videos on this subject are
excellent but no one takes you through the menu steps to achieve the
results.

--

*Dave - W?LEV*


--
Dave - W?LEV

Hi Stan, I gratefully will accept your kind offer of help. Thank you and I am not in a hurry. zapel406@...

Hi Dean and everyone who gave an answer firstly thank you. Yes I am using Nano Saver on my laptop, yes I am aware of how to calibrate and the importance of measuring at the plane, yes I have made jigs and am aware of stray inductance and capacitance. Greg Messenger's videos seem to me to be the best way of using the nano vna to determine values but I don't seem to be able to replicate his menu settings and that is why I asked is Ver 1.2.27 different from earlier versions. All the videos on this subject are excellent but no one takes you through the menu steps to achieve the results.

Phil,
Even if you know how to use the VNA, measuring the QMX lowpass filters is tricky. I have done it a few times and can help you, but it would have to wait until Monday since I currently have family activities celebrating Easter. So if you would like me to walk you through it, please send me a message here and we can connect.

I second this! After you learn to properly calibrate the VNA in your test environment, look up YouTube videos on the Smith Chart, there are many. The chart will map resistance, inductance, and capacitance at every frequency of your sweep range... It's the key to getting the most from the VNA

Use Smith Chart. If your marker is in the upper half, it's inductive. If below, it's capacitance.

Sent from AT&T Yahoo Mail on Android

On Sat, Apr 19, 2025 at 7:46 AM, Jon via groups.io<vu2jo0@...> wrote: Dean,

Can you kindly explain the method you have used to measure inductance and
capacitance with NanoVNA?

73

Jon, VU2JO

On Sat, Apr 19, 2025 at 5:11?PM Dean - KC9REN via groups.io <deanberg2044=
[email protected]> wrote:

Phil, Are you using Nano VNASaver software on your computer to connect to
the NanoVNA or are you trying to do it directly? First thing to remember
is, Calibrate at the connection you are using to check your inductors or
capacitors etc. So if you are using alligator clips to connect to your
parts, you need to use a 50 ohm resistor at that spot. Lead lengths need to
be as short as possible because the wire leads do affect your readings.
There are several jigs you can make to check various components. Let me say
I am not real experienced with using the NanoVNA but I have used mine to
check inductors to read the uH value on my VNA H4 with some success. I have
found using my L/C meter is much simpler. There may be someone out there
that has more experience with this than I but I will watch this thread and
try to help you if I can.
Dean - KC9REN

On Sat, Apr 19, 2025 at 01:25 AM, Phil Brown wrote:

Hi Everyone, I'm new to the VNA and trying to measure both inductance and
capacitance but getting stupid results. Is there someone who has this

version

of the VNA could walk me through the setup and menu to do this please. I

have

checked and checked the various You Tube videos but I am not getting the
results I should. I should also mention I am 80 years old. Trying to

complete

my QMX low pass filters. Failing to get any answers is there someone who

would

care to correspond by email with me. Very frustrated. Thank you for

looking.

Dean,

Can you kindly explain the method you have used to measure inductance and
capacitance with NanoVNA?

73

Jon, VU2JO

On Sat, Apr 19, 2025 at 5:11?PM Dean - KC9REN via groups.io <deanberg2044=
[email protected]> wrote:

Phil, Are you using Nano VNASaver software on your computer to connect to
the NanoVNA or are you trying to do it directly? First thing to remember
is, Calibrate at the connection you are using to check your inductors or
capacitors etc. So if you are using alligator clips to connect to your
parts, you need to use a 50 ohm resistor at that spot. Lead lengths need to
be as short as possible because the wire leads do affect your readings.
There are several jigs you can make to check various components. Let me say
I am not real experienced with using the NanoVNA but I have used mine to
check inductors to read the uH value on my VNA H4 with some success. I have
found using my L/C meter is much simpler. There may be someone out there
that has more experience with this than I but I will watch this thread and
try to help you if I can.
Dean - KC9REN

On Sat, Apr 19, 2025 at 01:25 AM, Phil Brown wrote:

Hi Everyone, I'm new to the VNA and trying to measure both inductance and
capacitance but getting stupid results. Is there someone who has this

version

of the VNA could walk me through the setup and menu to do this please. I

have

checked and checked the various You Tube videos but I am not getting the
results I should. I should also mention I am 80 years old. Trying to

complete

my QMX low pass filters. Failing to get any answers is there someone who

would

care to correspond by email with me. Very frustrated. Thank you for

looking.

Phil, Are you using Nano VNASaver software on your computer to connect to the NanoVNA or are you trying to do it directly? First thing to remember is, Calibrate at the connection you are using to check your inductors or capacitors etc. So if you are using alligator clips to connect to your parts, you need to use a 50 ohm resistor at that spot. Lead lengths need to be as short as possible because the wire leads do affect your readings. There are several jigs you can make to check various components. Let me say I am not real experienced with using the NanoVNA but I have used mine to check inductors to read the uH value on my VNA H4 with some success. I have found using my L/C meter is much simpler. There may be someone out there that has more experience with this than I but I will watch this thread and try to help you if I can.
Dean - KC9REN

Though I have been using NanoVNA for a few weeks now, I was not aware that
it can be used for measuring inductance and capacitance. Now I will also
join your search!
Currently I use my LCR meter to measure inductance and capacitance.

73
Jon, VU2JO

On Sat, Apr 19, 2025 at 11:56?AM Phil Brown via groups.io <zapel406=
[email protected]> wrote:

Hi Everyone, I'm new to the VNA and trying to measure both inductance and
capacitance but getting stupid results. Is there someone who has this
version of the VNA could walk me through the setup and menu to do this
please. I have checked and checked the various You Tube videos but I am not
getting the results I should. I should also mention I am 80 years old.
Trying to complete my QMX low pass filters. Failing to get any answers is
there someone who would care to correspond by email with me. Very
frustrated. Thank you for looking.

Hi Everyone, I'm new to the VNA and trying to measure both inductance and capacitance but getting stupid results. Is there someone who has this version of the VNA could walk me through the setup and menu to do this please. I have checked and checked the various You Tube videos but I am not getting the results I should. I should also mention I am 80 years old. Trying to complete my QMX low pass filters. Failing to get any answers is there someone who would care to correspond by email with me. Very frustrated. Thank you for looking.

On Thu, Apr 17, 2025 at 02:51 AM, Steve Withnell wrote:

Is this the reference to what you are trying to do?

Yes, that is the reference choke...

Is this the reference to what you are trying to do?

Hi

The choc of john its exactly an 1/1 balun made by a lot of ferrites, measuring a balun with an NanoVNA on a chack its a thing and results of balun mounted with a dipole antenna was a different subject, indeed the efficiency of a balun depend on frequency's , dipole designe and how the external shield was used ... Just an other subject.
Normalised measurement of balun is simplfyed to an S11 IzI or S21 thru measurements
73s Nizar

On Tue, Apr 15, 2025 at 10:44 PM, Team-SIM SIM-Mode wrote:

S21 thru Logmag measurement is prefered to be done with a 150 Ohm renormalized
Z0

I think this is not correct in this case, Nizar. Measuring the choke is not measuring a transmission line with specific characteristic impedance that needs matched; it is more like measuring an inductor - and that should be done at the 50-ohm impedance of the nanovna.

I wouldn't really describe this as a "common mode" (although that is used) - it's really better conceptualized as a third wire which is connected to the feedpoint, as Roger said. As noted, the choke adds an impedance in the wire.

Roger's other comment is well taken - what you measure on the bench may not be what's in practice.

You can play around with this in NEC pretty easily. I just add a wire to represent the coax shield (outside) and throw a lumped load in where needed.

Unfortunately, NEC doesn't have a way to have a frequency varying load, but I've done that in Python to generate NEC input files. 4NEC2 or EZNEC might have a way to do it. FairRite publishes .xls files with the properties of the materials, which you can use to to calculate R and X.



#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
routines to read ferrite data sheets
and calculate series impedance given frequency, etc
Created on Tue Aug 25 15:40:15 2020
@author: jimlux
"""
import matplotlib.pyplot as plt
import os
import numpy as np
""" typical file from FairRite:
77 material,,
Frequency(Hz),&micro;',&micro;''
1.00E+04,1989,14
1.00E+05,2001,37
"""

def readdata(filename):
""" encoding needed, because there's a "mu" character in the file, and UTF-8 dies"""
mu = np.genfromtxt(filename,delimiter=',',skip_header=2, encoding='Latin-1')
return (mu)
def toroidLzero(N,OD,ID,Length):
""" returns Lzero in nanoHenry, given dimensions in mm
"""
L0=0.0461 * N**2 * np.log10(OD/ID) * Length * 10
return(L0)

class ferriteloading:
""" class to support generalized management of ferrite properties"""
def __init__(self):
self.datatab={}

def addmix(self, filename,mixid=None):
""" adds a new mix to the library. Mix is specified as a csv file, from FairRite.
if a mix id isn't specified, the first two characters of the filename are used.
mix ids are *strings*
"""
mutab = readdata(filename)
muf = np.array(mutab[:,0])
mu = np.array(mutab[:,1] + 1j * mutab[:,2],dtype=complex)
if not mixid:
mixid = os.path.split(filename[:2])[1]
if not isinstance(mixid,str):
mixid = "%d"%mixid
self.datatab.update({mixid:[muf,mu]}) #if we make this a 2d array, then frequencies are complex


def mu(self,mix,freq):
if not isinstance(mix,str):
mix= "%d"%mix
x=self.datatab[mix]
mu = np.interp(freq,x[0],x[1])
return mu


if __name__ == "__main__":
mixlist = [31,73,75,76,77,78]
OD = 4.0
ID = 3.0
Length = 1000.
Lzero = toroidLzero(1, OD, ID, Length)

for mix in mixlist:
mixfile = "%2d-Material-Fair-Rite.csv"%mix
print(mixfile)
mu = readdata(mixfile)
f = mu[:,0]
muprime = mu[:,1]
mudoubleprime = mu[:,2]
omega = 2 * np.pi * f
R = omega*mudoubleprime * Lzero * 1E-9
X = omega * muprime * Lzero * 1E-9
plt.figure()
plt.semilogx(f,R)
plt.semilogx(f,X)
plt.title(mixfile)
plt.xlabel("Frequency")
plt.ylabel("Ohms")
plt.legend(["Real","Imag"])
plt.grid()
plt.savefig("%2d-mix.png"%mix)


""" now test the class based implementation """

ferrites = ferriteloading()
for mix in mixlist:
mixfile = "%2d-Material-Fair-Rite.csv"%mix
print(mixfile)
ferrites.addmix(mixfile,mix)

for mix in mixlist:
print(mix,ferrites.mu(mix,1e6))

Users of a Maxwell or W2DU choke need to be aware that the effectiveness in reducing common mode current is not directly related to the magnitude of the impedance |Z| or S21 loss that they measure using a VNA.

When a balanced dipole is fed with an unbalanced transmission line, like coaxial cable, there will be RF radiation from the coaxial cable. The reason why requires some explanation. The power fed to the antenna travels along the inner conductor and the inner surface of the coax shield. The outer surface of the shield is separated from the inner surface due to the skin effect which takes place at RF frequencies. In effect the outer surface of the shield is a "third wire" which is connected to the half of the dipole attached to the shield at the feedpoint. So the antenna now consists of one wire connected to the inner conductor and two wires connected to the shield. The end result is that current is flowing on the outer surface of the shield. The common mode current level will depend on many factors such as operating frequency, the antenna geometry, length of the coax and how grounding is done at the transmitter end.

A Maxwell or W2DU ferrite choke effectively places an inductor in series with the outer surface of the shield. This inductor will have a complex impedance (resistive R and reactive X) that is determined by the ferrite mix, physical parameters of the core and the number of turns. The more resistive the better but the value of X can work for or against reducing common mode current. When considering the inductor as a "loading coil" most readers will know that this can make a radiating element have increased current flow (and hence better radiation at a specific frequency) because the inductive reactance can cancel capacitive reactance. So when measuring the Maxwell one needs to aware that measuring |Z| or S21 on the bench and making assumptions can lead to false conclusions. Making S11 measurements of R and X on a NanoVNA can be accurate to 5% or so up to several thousand ohms as I have shown in other measurement posts in this group.

The bottom line is that S11 or S21 measurements can give some insights into choke parameters but the only real test of effectiveness is to build a simple RF current meter that can slope up and down the coax and measure the actual common mode current.

Roger Need

On Tuesday 15 April 2025 03:00:25 pm DouglasK wrote:

I have a NanoVNA (2.8" screen) from about 2020. Overall it works well, but the Jog Switch doesn't do anything.

The touch screen works fine, it calibrates OK and measures SWR with ease... but the jog switch doesn't do anything. Should it do anything?

I had bought one off ebay and it arrived in the smallest possible box, and when I took it out of the box that switch was at a rather odd angle, and did nothing. I returned that one, no issues with the seller, and ultimately bought one from R&L...


--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

Hi

S11 Smith measurements or S11 IZI is also possible , it should have higher then 1500 Ohm as mentionned by the paper , no care with one wire or two wire connected together , it should be very similaire .

S21 thru Logmag measurement is prefered to be done with a 150 Ohm renormalized Z0 and have more then 20db attenuation, this needs Dislord firmware renormalisation function , not all NanoVNA's has this advanced function, NanoVNA-H or H4 , liteVNA. Has it .
73s Nizar

I find the jog wheel quite useful for moving the marker. Alternatively you
can use the Search Minimum function in the menu to find minimum SWR point
in the tracing.

I have not opened the casing for fear of damaging it! Even now, there is
some loose contact somewhere: Sometimes when I switch on, the screen is
blank. Switch off and switch on, the screen comes up well.

73

Jon, VU2JO

On Wed, Apr 16, 2025 at 12:30?AM DouglasK via groups.io <VE3YDK=
[email protected]> wrote:

I have a NanoVNA (2.8" screen) from about 2020. Overall it works well, but
the Jog Switch doesn't do anything.

The touch screen works fine, it calibrates OK and measures SWR with
ease... but the jog switch doesn't do anything. Should it do anything?

Firmware is reasonably current with version 1.2.43 (p: 101 IF: 12k, ADC:
192K, Lcd:320x240)
Build time: Feb 19 2025 - 21:39:08

Am I missing anything by just using it via touch screen? An inquiring
mind wants to know!

--
---
Do Justly Love Mercy. Walk Humbly.

Ooooopps...... I looked at the picture but saw what I expected: Coax.
Thanks, Stan, for bringing this to my attention.

Test just like my common mode chokes on toroids. Either or both wires will
do.

Dave - W?LEV

On Tue, Apr 15, 2025 at 8:28?PM Stan Dye via groups.io <standye=
[email protected]> wrote:

In this case, Dave, if you look at his picture, he is using two wires for
the choke conductors, not a coax. So either or both wires together should
work.

--

*Dave - W?LEV*


--
Dave - W?LEV