|
Dear David,
Q measurement is a very interesting subject, especially to someone who competes in Top Band Direction Finding events.? The subject is glossed over in many modern textbooks but is covered in Foundations of Wireless and Radio and Laboratory Handbook, both by M G Scroggie B.Sc., M.I.E.E.
The Q Meter in theory and practice from Marconi Instruments contains excerpts from the manuals for the TF1245 and TF1246 and is essential reading for operators of similar instruments.
Interesting references are:
An overlooked Q meter is the Advance T1 & T2 series:
A design from Australia was featured in Electronics Australia June 1969.
A more recent design is a Novel Q Meter from EDN:
The Xtal Set Society has some fascinating articles on their site about Q but the links are not working this evening:
From memory some of their measurements were made using an HP 4342A which seems to be a rare instrument these days.
Many years ago I bought a TF 1245 and its companion oscillators TF 1246 and TF 1247; all three languished in storage until the start of the pandemic which gave me an opportunity to start overhauling them.? That was a long job, with the TF 1245 requiring a considerable amount of work including the rebuilding of a capacitor, replacement of a feed through capacitor (only a few left in stock at Farnell) and the rebuilding of the Q multiplier meter with parts obtained from a similar meter on EBay, the seller will be stunned if he ever finds out the proxy that I entered.
The TF 1246 tried to defy logical fault finding until I disconnected and measured all the resisters and then replaced them.
After that the two units were left on test 24 hours a day for 7 days before realignment, all of this took over a month.? A special jig was then made to test various antennas.
A problem with home constructed units is getting very low oscillator output impedance and a high Q variable capacitor.? The variable capacitor is, of course, in parallel with the inductor being measured, size and weight preclude the very high quality Marconi item from being transplanted into my Direction Finding receiver.
It would be possible to use high quality fixed capacitors and switch them into circuit via microprocessor control in a similar way to that used in automatic antenna matching / tuning units.
As I am sure you know Q (ul) is mainly theoretic, what matters are the loaded Q, Q(L) which will be changed by surrounding components and metal work.
Q of a varicap is usually given as about 200 and is a limiting factor in a DF receiver with 3 or 4 switches tuned frequencies.
Measurement using an oscilloscope or spectrum analyser is often mentioned but it can be difficult to judge 3, 6 or 20 dB on either side of resonance.? I have used an HP 3400A ac millivoltmeter and frequency counter with success.? Those instruments can be connected to the inductor via an FET source follower with several Megohms input impedance.? To avoid interaction with the coaxial connecting lead a differential amplifier can be used.
?
73, Geoffrey.
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On Thu, Aug 11, 2022 at 02:24 PM, Myosotis wrote:
Measurement using an oscilloscope or spectrum analyzer is often mentioned but it can be difficult to judge 3, 6 or 20 dB on either side of resonance.?
Back when I was measuring a lot of coil Qs using the 3db method and a scope, I figured out that 5 / 7 = 0.714, which is so close to 0.707, that on a scope you can't see the difference.
So, I would peak the signal at resonance, log the frequency, then use the variable knob (uncal) to set the waveform to 7 units, then move the oscillator frequency up until the scope read 5 units, log the frequency, then move the oscillator frequency down until the scope reads 5 units and log the frequency. The 0.714 vs 0.707 is a 3.5% error, however you are reading the upper 3db frequency lower than it actually is and you also reading the lower 3db frequency lower than it actually is (tiny amounts), so this almost cancels out, except for the geometric mean difference. Geometric mean - the 3db points don't have the exact same frequency difference from resonance, it is the geometric mean.
? Maybe someone smarter than I can figure out a correction factor, and tell me if it changes with Q. I suspect it does. and you would need a chart with a line showing Q vs Correction factor or vice versa. I would actually like to see that chart if anyone is interested in giving me enough info. I don't have much of a math background, so I will probably struggle with the info.
? I thought this site presented some useful info about measuring Q.
???????????????????????????????????? Mikek
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Hello All,
Measuring the Q factor may be easily done with a VNA or a nanoVNA, for instance.
The measurement set-up cannot be simpler:
Connect the L and C in series and in shunt across a transmission line and measure the S21 parameter
at the frequency(ies) of interest.? The reference capacitor is used to establish resonance.
This should be a low loss capacitor (a vacuum capacitor perhaps).
Measure the loss (S21) at the resonant frequency, and below and above the resonant frequency.
Enter these points in the Excel sheet that I designed.?? It reports the component values ESR and Q...
See:?
For crystal Q measurements:
Calculate the Loaded and Unloaded Q Factor of a Resonator:
Q Factor Measurements with an SWR Meter:
??????? Link to spreadsheet:
Jacques,? VE2AZX
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On Sat, 13 Aug 2022 at 15:37, Jacques Audet < Jacaudet@...> wrote: Hello All,
Measuring the Q factor may be easily done with a VNA or a nanoVNA, for
instance.
The measurement set-up cannot be simpler:
Connect the L and C in series and in shunt across a transmission line
and measure the S21 parameter
at the frequency(ies) of interest.? The reference capacitor is used to
establish resonance.
This should be a low loss capacitor (a vacuum capacitor perhaps).
Measure the loss (S21) at the resonant frequency, and below and above
the resonant frequency.
There's a 105 page paper from Andrew Gregory at NPL on this topic.
along with some MATLAB/Octave and Python code. That fits multiple points on the transmission curve - not just 3. One significant difference from a simple S21 measurement with a VNA is that there is a lot (40 dB) attenuation added in series with the inductor/capacitor.
> Jacques,? VE2AZX
If I recall correctly, I see something similar from yourself in your QEX paper, where capacitors of around 1 pF were used. When I went looking for more information on this, it seems the coupling needs to be identical on both sides of the coil. Whilst that is easy to achieve if the capacitors are 1000 pF, it is not so easy when the capacitors are very small.
Dave, G8WRB.
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Thanks for the NPL paper.
My Q factor measurement technique is as simple as possible.
It only requires amplitude ratios to be measured.? No angle measurement is required.
Both series and shunt modes connections are supported, as shown in my Excel document.
The useful frequency range is below 1 GHz.
Of course results will be more precise with a 'professional' type VNA, using two port full mismatch corrections.
The user may / should measure S21 at various attenuation levels and see the effect on the computed Q factor.
This procedure could be automated too.
Regarding 1 pF capacitor accuracy, these may be measured in the series mode with a VNA by measuring S21 and
computing the capacitance value.
Jacques? VE2AZX
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On Sun, 14 Aug 2022 at 19:33, Jacques Audet < Jacaudet@...> wrote: Thanks for the NPL paper.
My Q factor measurement technique is as simple as possible.
It only requires amplitude ratios to be measured.? No angle measurement
is required.
Both series and shunt modes connections are supported, as shown in my
Excel document.
The useful frequency range is below 1 GHz.
Of course results will be more precise with a 'professional' type VNA,
using two port full mismatch corrections.
The user may / should measure S21 at various attenuation levels and see
the effect on the computed Q factor.
This procedure could be automated too.
I have used MATBAB/Octane a but, but it wasn¡¯t clear to me that the NPL code could read a Touchstone file.?
Regarding 1 pF capacitor accuracy, these may be measured in the series
mode with a VNA by measuring S21 and
computing the capacitance value.
That is okay in a test jig for small capacitors, but less suitable if trying to measure the capacitance between a wire from the source in a Q-meter and a wire from the detector.?
For some experiments at least, my intention was to use Banana sockets spaced 25.4 mm apart, which is what HP and Boonton used. That would allow comparisons with Q-standard coils like the attached. (It was sitting on a bench, connected to an HP 4284A LCR meter when the photograph was taken. I have turned the photograph through 180¡ã so the writing is up the right way. It is not attached to the ceiling as it looks in the photograph). ???
Jacques? VE2AZX
G8WRB -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
|
There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Jacques Audet Sent: Monday, 15 August 2022 4:34 AM To: [email protected]Subject: Re: [Test Equipment Design & Construction] Making a Q-meter / References etc Thanks for the NPL paper. My Q factor measurement technique is as simple as possible. It only requires amplitude ratios to be measured. No angle measurement is required. Both series and shunt modes connections are supported, as shown in my Excel document. The useful frequency range is below 1 GHz. Of course results will be more precise with a 'professional' type VNA, using two port full mismatch corrections. The user may / should measure S21 at various attenuation levels and see the effect on the computed Q factor. This procedure could be automated too. Regarding 1 pF capacitor accuracy, these may be measured in the series mode with a VNA by measuring S21 and computing the capacitance value. Jacques VE2AZX
|
Seems odd that they don't compare machines at a series of frequencies from 0.130MHz to 25 MHz, at least to the particular machines capabilities.
It reads like they are making news that Q varies with frequency.
?????????????????????????????????? Mikek
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It is wise not only to measure the Q of inductors, but also the capacitors one
plans to use in circuits. I learned that lesson the hard way in 1979. I was working
as the stooge for an RF Design Engineer. He assigned me to build and test
some Tchebychev 5th order filters using hand wound coils and surface mount
capacitors. The coils were wound using 10-32 machine screws as mandrels.
Inductor Q was measured with an HP-4342A and found to run nominally around
120 over the frequency range of 110 MHz to 250 MHz. Instructions were to use
the capacitors in the provided sample kits. Cap testing per instructions was to be
only measuring the value, not worry about Q as time was critical and the caps
would have a Q much higher than the inductors anyway.
That turned into a serious problem. While the surface mount caps provided
excellent Q at 21.4 MHz (about 450), the NPO material used in the caps ran out
of steam at around 90 MHz. It left an indelible lesson, to this day I characterize
each part used in a new design.
In the ensuing years, I made it a point to buy parts from manufacturers whose
parts were previously vetted. In particular when I see a low cost surface mount
NPO material kits, my junk detector alerts.? I find it more economical to buy
more expensive parts as the lower cost items often do not work as expected
and burn my time.
Chuck WD4HXG
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On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...> wrote: There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same document I think you are,
I am not impressed by the methodology in that document?
They have taken a selection of instruments (a Q-meter, inductance meter, LC meter and impedance analyzer), and tested one inductor at specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz and 100 MHz). The measured value varied between 594.0 nH & 1300 nH.?
At only one frequency (130 kHz) were two instruments used to measure the same device
Surely it would have been sensible to provide further results.
1) At a frequency at which all the instruments will operate (1 MHz). Then you are comparing apples to apples.
2) Show how the measured inductance changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will continue to use the results that would be measured on a
HP 4342A Q-meter, is that historically it has been done that way. They even say they will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of measurements were made using the Tektronix LC130 L&C? meter and the HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A impedance analyzer indicated L=607 nH at the same frequency of 130 kHz. That's a pair of measurements taken under similar conditions, but giving very different answers.
An interesting trio of measurements were at 130 kHz, 1 MHz and 10 MHz using 2 different instruments (HP 4192A impedance analyzer and Boonton 62A inductance meter). All 3 answers were within 0.17% of each other, despite the factor of 77 between the different frequencies.
As you say George, the results of the paper and intersting, but I felt the note was rather lacking in substance. I am pretty sure no journal would have published that as a paper, as there's no analysis of the results.
Dave
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On Mon, Aug 15, 2022 at 06:42 PM, Chuck Moore wrote:
While the surface mount caps provided
excellent Q at 21.4 MHz (about 450), the NPO material used in the caps ran out
of steam at around 90 MHz.
Years ago I was designing low noise VCOs and synthesizers for VHF and UHF mobile radios.? As part of this work I tested capacitors from different vendors for suitability at the frequencies of interest.? I found that some brands were more like resistors than capacitors, some even at frequencies as low as a few MHz.? The capacitor brands that I found to be best were Murata and Panasonic.? Because mobile radio is a price competitive market, expensive microwave capacitors were not considered for these products and weren't tested.? I assume that many of those would have adequate performance at VHF/UHF.
|
A 1955 Monograph?from the Bell Labs Series. ?Some might find this an interesting background,?else delete.
Pete G4GJL
On Tue, Aug 16, 2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote: On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...> wrote: There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same document I think you are,
I am not impressed by the methodology in that document?
They have taken a selection of instruments (a Q-meter, inductance meter, LC meter and impedance analyzer), and tested one inductor at specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz and 100 MHz). The measured value varied between 594.0 nH & 1300 nH.?
At only one frequency (130 kHz) were two instruments used to measure the same device
Surely it would have been sensible to provide further results.
1) At a frequency at which all the instruments will operate (1 MHz). Then you are comparing apples to apples.
2) Show how the measured inductance changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will continue to use the results that would be measured on a
HP 4342A Q-meter, is that historically it has been done that way. They even say they will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of measurements were made using the Tektronix LC130 L&C? meter and the HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A impedance analyzer indicated L=607 nH at the same frequency of 130 kHz. That's a pair of measurements taken under similar conditions, but giving very different answers.
An interesting trio of measurements were at 130 kHz, 1 MHz and 10 MHz using 2 different instruments (HP 4192A impedance analyzer and Boonton 62A inductance meter). All 3 answers were within 0.17% of each other, despite the factor of 77 between the different frequencies.
As you say George, the results of the paper and intersting, but I felt the note was rather lacking in substance. I am pretty sure no journal would have published that as a paper, as there's no analysis of the results.
Dave
|
toggle quoted message
Show quoted text
On Aug 18, 2022, at 9:51 AM, Pete_G4GJL <g4gjl.uk@...> wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting background,?else delete.
Pete
G4GJL
On Tue, Aug 16, 2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote: On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...> wrote: There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same document I think you are,
I am not impressed by the methodology in that document?
They have taken a selection of instruments (a Q-meter, inductance meter, LC meter and impedance analyzer), and tested one inductor at specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz and 100 MHz). The measured value varied between 594.0 nH & 1300 nH.?
At only one frequency (130 kHz) were two instruments used to measure the same device
Surely it would have been sensible to provide further results.
1) At a frequency at which all the instruments will operate (1 MHz). Then you are comparing apples to apples.
2) Show how the measured inductance changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will continue to use the results that would be measured on a
HP 4342A Q-meter, is that historically it has been done that way. They even say they will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of measurements were made using the Tektronix LC130 L&C? meter and the HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A impedance analyzer indicated L=607 nH at the same frequency of 130 kHz. That's a pair of measurements taken under similar conditions, but giving very different answers.
An interesting trio of measurements were at 130 kHz, 1 MHz and 10 MHz using 2 different instruments (HP 4192A impedance analyzer and Boonton 62A inductance meter). All 3 answers were within 0.17% of each other, despite the factor of 77 between the different frequencies.
As you say George, the results of the paper and intersting, but I felt the note was rather lacking in substance. I am pretty sure no journal would have published that as a paper, as there's no analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
It was an attachment to the
email, mine was at the bottom left in my email program,
(Thunderbird).
Interesting short read of the history of Q.
On 8/18/2022 8:56 AM, Chuck Moore via
groups.io wrote:
toggle quoted message
Show quoted text
Where is the link?
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting
background,?else delete.
Pete
G4GJL
On Tue, Aug 16, 2022 at
7:56 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...>
wrote:
On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...>
wrote:
There is an interesting engineering note
from Vishay on the subject of measuring
inductance with various pieces of test
equipment (including the 4342A) at various
frequencies. They quote up to 100% variation
in readings on a single test sample (!)
"Frequency Dependance of Inductor
Testing and Correlation of Results Between Q
Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the
4342A.
Cheers,
George
VK2KGG
If you are talking about the
same document I think you are,
I am not impressed by the
methodology in that document?
They have taken a selection of
instruments (a Q-meter, inductance meter, LC
meter and impedance analyzer), and tested one
inductor at specific frequencies (130 kHz, 1
MHz, 10 MHz, 25 MHz and 100 MHz). The measured
value varied between 594.0 nH & 1300 nH.?
At only one frequency (130 kHz) were two
instruments used to measure the same device
Surely it would have been
sensible to provide further results.
1) At a frequency at which all
the instruments will operate (1 MHz). Then you
are comparing apples to apples.
2) Show how the measured
inductance changes with frequency on the HP
4342A Q-meter.
Their only real reason for staying they
will continue to use the results that would be
measured on a HP 4342A Q-meter, is that
historically it has been done that way. They
even say they will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of
measurements were made using the Tektronix
LC130 L&C? meter and the HP 4192A
impedance analyzer. The Tektronix LC130
indicated L=1300.0 nH and the HP 4192A
impedance analyzer indicated L=607 nH at
the same frequency of 130 kHz. That's a
pair of measurements taken under similar
conditions, but giving very different answers.
An interesting trio of measurements were at
130 kHz, 1 MHz and 10 MHz using 2 different
instruments (HP 4192A impedance analyzer and
Boonton 62A inductance meter). All 3 answers
were within 0.17% of each other, despite the
factor of 77 between the different
frequencies.
As you say George, the results of the paper
and intersting, but I felt the note was rather
lacking in substance. I am pretty sure no
journal would have published that as a paper,
as there's no analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
Chuck, and probably others.............
It looks like attachments are not allowed here. I scanned and attached the document, so I guess it got stripped off... My apologies for wasting your time and bandwidth.
Ive tried to upload to the file section but that does not seem possible either.
Not sure how to progress atm.
Pete
Where is the link?
On Aug 18, 2022, at 9:51 AM, Pete_G4GJL < g4gjl.uk@...> wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting background,?else delete.
Pete
G4GJL
On Tue, Aug 16, 2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote: On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...> wrote: There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same document I think you are,
I am not impressed by the methodology in that document?
They have taken a selection of instruments (a Q-meter, inductance meter, LC meter and impedance analyzer), and tested one inductor at specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz and 100 MHz). The measured value varied between 594.0 nH & 1300 nH.?
At only one frequency (130 kHz) were two instruments used to measure the same device
Surely it would have been sensible to provide further results.
1) At a frequency at which all the instruments will operate (1 MHz). Then you are comparing apples to apples.
2) Show how the measured inductance changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will continue to use the results that would be measured on a
HP 4342A Q-meter, is that historically it has been done that way. They even say they will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of measurements were made using the Tektronix LC130 L&C? meter and the HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A impedance analyzer indicated L=607 nH at the same frequency of 130 kHz. That's a pair of measurements taken under similar conditions, but giving very different answers.
An interesting trio of measurements were at 130 kHz, 1 MHz and 10 MHz using 2 different instruments (HP 4192A impedance analyzer and Boonton 62A inductance meter). All 3 answers were within 0.17% of each other, despite the factor of 77 between the different frequencies.
As you say George, the results of the paper and intersting, but I felt the note was rather lacking in substance. I am pretty sure no journal would have published that as a paper, as there's no analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
Attachments came through fine on my end.?
toggle quoted message
Show quoted text
Chuck, and probably others.............
It looks like attachments are not allowed here. I scanned and attached the document, so I guess it got stripped off... My apologies for wasting your time and bandwidth.
Ive tried to upload to the file section but that does not seem possible either.
Not sure how to progress atm.
Pete
Where is the link?
On Aug 18, 2022, at 9:51 AM, Pete_G4GJL < g4gjl.uk@...> wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting background,?else delete.
Pete
G4GJL
On Tue, Aug 16, 2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote:
On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...> wrote:
There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same document I think you are,
I am not impressed by the methodology in that document?
They have taken a selection of instruments (a Q-meter, inductance meter, LC meter and impedance analyzer), and tested one inductor at specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz and 100 MHz). The measured value varied between 594.0
nH & 1300 nH.? At only one frequency (130 kHz) were two instruments used to measure the same device
Surely it would have been sensible to provide further results.
1) At a frequency at which all the instruments will operate (1 MHz). Then you are comparing apples to apples.
2) Show how the measured inductance changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will continue to use the results that would be measured on a HP 4342A Q-meter, is that historically it has been done that way. They even say they will not necessarily use a? HP 4342A Q-meter for the testing.
One interesting? couple of measurements were made using the Tektronix LC130 L&C? meter and the HP 4192A impedance analyzer. The Tektronix LC130 indicated L=1300.0 nH and the HP 4192A impedance analyzer indicated L=607 nH at the same frequency
of 130 kHz. That's a pair of measurements taken under similar conditions, but giving very different answers.
An interesting trio of measurements were at 130 kHz, 1 MHz and 10 MHz using 2 different instruments (HP 4192A impedance analyzer and Boonton 62A inductance meter). All 3 answers were within 0.17% of each other, despite the factor of 77 between the different
frequencies.
As you say George, the results of the paper and intersting, but I felt the note was rather lacking in substance. I am pretty sure no journal would have published that as a paper, as there's no analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
It was attached in the email feed...
On 8/18/2022 10:45 AM, Pete_G4GJL wrote:
toggle quoted message
Show quoted text
Chuck, and probably others.............
It looks like attachments are not allowed here. I scanned
and attached the document, so I guess it got stripped off...
My apologies for wasting your time and bandwidth.
Ive tried to upload to the file section but that does not
seem possible either.
Not sure how to progress atm.
Pete
Where is the link?
On Aug 18, 2022, at 9:51 AM, Pete_G4GJL < g4gjl.uk@...>
wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting
background,?else delete.
Pete
G4GJL
On Tue, Aug 16,
2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave
Ltd < drkirkby@...>
wrote:
On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...>
wrote:
There is an interesting engineering
note from Vishay on the subject of
measuring inductance with various
pieces of test equipment (including
the 4342A) at various frequencies.
They quote up to 100% variation in
readings on a single test sample (!)
"Frequency Dependance of Inductor
Testing and Correlation of Results
Between Q Meters and Impedance Meters"
(sic)
Google: Vishay 34093
Their conclusion was to stick with
the 4342A.
Cheers,
George
VK2KGG
If you are talking about
the same document I think you are,
I am not impressed by
the methodology in that document?
They have taken a
selection of instruments (a Q-meter,
inductance meter, LC meter and impedance
analyzer), and tested one inductor at
specific frequencies (130 kHz, 1 MHz, 10
MHz, 25 MHz and 100 MHz). The measured
value varied between 594.0 nH & 1300
nH.? At only one frequency (130 kHz)
were two instruments used to measure the
same device
Surely it would have been
sensible to provide further results.
1) At a frequency at which
all the instruments will operate (1
MHz). Then you are comparing apples to
apples.
2) Show how the measured
inductance changes with frequency on the
HP 4342A Q-meter.
Their only real reason for staying
they will continue to use the results
that would be measured on a HP 4342A
Q-meter, is that historically it has
been done that way. They even say they
will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of
measurements were made using the
Tektronix LC130 L&C? meter and the
HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A
impedance analyzer indicated L=607 nH
at the same frequency of 130 kHz.
That's a pair of measurements taken
under similar conditions, but giving
very different answers.
An interesting trio of measurements
were at 130 kHz, 1 MHz and 10 MHz using
2 different instruments (HP 4192A
impedance analyzer and Boonton 62A
inductance meter). All 3 answers were
within 0.17% of each other, despite the
factor of 77 between the different
frequencies.
As you say George, the results of the
paper and intersting, but I felt the
note was rather lacking in substance. I
am pretty sure no journal would have
published that as a paper, as there's no
analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
It's not a universal problem - I got your attachement (and enjoyed skimming through it, I've saved it for later.)
I'm using Thunderbird running on Windows 10,
MK
|
I got the attachment, it
worked fine for me.
??????????????????????? Mikek
On 8/18/2022 10:45 AM, Pete_G4GJL
wrote:
toggle quoted message
Show quoted text
Chuck, and probably others.............
It looks like attachments are not allowed here. I scanned
and attached the document, so I guess it got stripped off...
My apologies for wasting your time and bandwidth.
Ive tried to upload to the file section but that does not
seem possible either.
Not sure how to progress atm.
Pete
Where is the link?
On Aug 18, 2022, at 9:51 AM, Pete_G4GJL < g4gjl.uk@...>
wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting
background,?else delete.
Pete
G4GJL
On Tue, Aug 16,
2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave
Ltd < drkirkby@...>
wrote:
On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...>
wrote:
There is an interesting engineering
note from Vishay on the subject of
measuring inductance with various
pieces of test equipment (including
the 4342A) at various frequencies.
They quote up to 100% variation in
readings on a single test sample (!)
"Frequency Dependance of Inductor
Testing and Correlation of Results
Between Q Meters and Impedance Meters"
(sic)
Google: Vishay 34093
Their conclusion was to stick with
the 4342A.
Cheers,
George
VK2KGG
If you are talking about
the same document I think you are,
I am not impressed by
the methodology in that document?
They have taken a
selection of instruments (a Q-meter,
inductance meter, LC meter and impedance
analyzer), and tested one inductor at
specific frequencies (130 kHz, 1 MHz, 10
MHz, 25 MHz and 100 MHz). The measured
value varied between 594.0 nH & 1300
nH.? At only one frequency (130 kHz)
were two instruments used to measure the
same device
Surely it would have been
sensible to provide further results.
1) At a frequency at which
all the instruments will operate (1
MHz). Then you are comparing apples to
apples.
2) Show how the measured
inductance changes with frequency on the
HP 4342A Q-meter.
Their only real reason for staying
they will continue to use the results
that would be measured on a HP 4342A
Q-meter, is that historically it has
been done that way. They even say they
will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of
measurements were made using the
Tektronix LC130 L&C? meter and the
HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A
impedance analyzer indicated L=607 nH
at the same frequency of 130 kHz.
That's a pair of measurements taken
under similar conditions, but giving
very different answers.
An interesting trio of measurements
were at 130 kHz, 1 MHz and 10 MHz using
2 different instruments (HP 4192A
impedance analyzer and Boonton 62A
inductance meter). All 3 answers were
within 0.17% of each other, despite the
factor of 77 between the different
frequencies.
As you say George, the results of the
paper and intersting, but I felt the
note was rather lacking in substance. I
am pretty sure no journal would have
published that as a paper, as there's no
analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
Pete
There is nothing to apologize for. I am grateful for your efforts.
I still find myself frequently snared by limitations on websites
which to me are not intuitively obvious.
One possible solution is:??
Their service allows you to upload a file up to 2 GB in size (use
to be 5GB but guess costs reduced their generosity.) and once
uploaded it provide a URL Link to the file you can include in
e-mails.
Again thanks.
Chuck WD4HXG
On Aug 18, 2022, at 11:45 AM, Pete_G4GJL <g4gjl.uk@...> wrote:
Chuck, and probably others.............
It looks like attachments are not allowed here. I scanned and attached the document, so I guess it got stripped off... My apologies for wasting your time and bandwidth.
Ive tried to upload to the file section but that does not seem possible either.
Not sure how to progress atm.
Pete
Where is the link?
On Aug 18, 2022, at 9:51 AM, Pete_G4GJL < g4gjl.uk@...> wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting background,?else delete.
Pete
G4GJL
On Tue, Aug 16, 2022 at 7:56 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote: On Tue, 16 Aug 2022 at 01:14, Labguy < georgg@...> wrote: There is an interesting engineering note from Vishay on the subject of measuring inductance with various pieces of test equipment (including the 4342A) at various frequencies. They quote up to 100% variation in readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and Correlation of Results Between Q Meters and Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same document I think you are,
I am not impressed by the methodology in that document?
They have taken a selection of instruments (a Q-meter, inductance meter, LC meter and impedance analyzer), and tested one inductor at specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz and 100 MHz). The measured value varied between 594.0 nH & 1300 nH.?
At only one frequency (130 kHz) were two instruments used to measure the same device
Surely it would have been sensible to provide further results.
1) At a frequency at which all the instruments will operate (1 MHz). Then you are comparing apples to apples.
2) Show how the measured inductance changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will continue to use the results that would be measured on a
HP 4342A Q-meter, is that historically it has been done that way. They even say they will not necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of measurements were made using the Tektronix LC130 L&C? meter and the HP 4192A impedance analyzer. The
Tektronix LC130
indicated L=1300.0 nH and the HP 4192A impedance analyzer indicated L=607 nH at the same frequency of 130 kHz. That's a pair of measurements taken under similar conditions, but giving very different answers.
An interesting trio of measurements were at 130 kHz, 1 MHz and 10 MHz using 2 different instruments (HP 4192A impedance analyzer and Boonton 62A inductance meter). All 3 answers were within 0.17% of each other, despite the factor of 77 between the different frequencies.
As you say George, the results of the paper and intersting, but I felt the note was rather lacking in substance. I am pretty sure no journal would have published that as a paper, as there's no analysis of the results.
Dave
<Bell Mono _Q_small.pdf>
|
Dr. David Kirkby, Kirkby Microwave Ltd
Jim Allyn - N7JA
Pete_G4GJL