Re: Open source impedance analyzer
Mike, and others,
Eli got there before you asked! It's to be found at .
HTH, 73, thanks to Eli,
Robin, G8DQX
On 07/09/2022 09:36, Michael Kellett
wrote:
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Hello Eli,
Thank you for sharing your work.
I had a quick look at your design on Github but it turned out
to be a very superficial look because the schematics are only in
Kicad format.
I know Kicad is free but the time to install it and get to know
it isn't.
It would be very helpful if you were also to present the
schematics as .pdf which I think pretty much everyone has a way
of reading.
Of course it's your project and your time and I am well aware
that I'm asking you to do something extra - I do think you would
attract more interest and maybe more useful comment.
Michael Kellett,
MK Electronics Ltd.,
Unit 4,
Greenlaw,
Castle Douglas,
DG7 2LH,
01556 506999
07968 111148
On 06/09/2022 23:13, Eli M wrote:
Below are my accuracy test plots-- of course take everything
with a grain (or handful) of salt because I don't have a
calibrated set of resistors/capacitors, and I'm still a student
learning the field. The raw data is all in the github with the
scripts to make these plots (written in Julia).
The fact the board only has two shunt resistors is a major
limitation of the design for a general audience. I almost
measure components within 100m-10k range so 100 Ohm shunt does
the job. I figure anybody willing to populate a PCB and use a
DAQ should know the application well enough to pick the right
resistors for the job.?
My plan is to make a set of loads in shielded enclosures with
BNC connectors on each such that the connection is repeatable on
different meters. The Kelvin clips are a good start minimizing
the effect of contact resistance, but still end up being moved
changing the parasitic values, which is especially harmful to
the measurement at 100 kHz. Then I'd gladly send the loads to
whoever would like to test and there can be a level of certainty
that there are no connection errors. Also using low tempco
resistors is probably important for this. Now that I think of
it, I'll probably make a design shortly and start a new thread
on the matter because it is a bit tangential, and I think there
are plenty of readers who would have helpful insights on it.?
-Eli
1kHz resistor
measurements:
10kHz resistor
measurements:
100kHz measurement:
Capacitors @ 10kHz:
Ceramic below 1μF, radial film 1μF and above
|
Seems like you have all the info you need. Standard US fine thread screw would be a 1/4"-28. (coarse thread is 1/4"-20)
I checked the binding posts on my Boonton 260A and the are 1/4"? fine thread.
??????????????????????????????????????????????????????????????? Mikek
|
Re: Open source impedance analyzer
Hello Eli,
Thank you for sharing your work.
I had a quick look at your design on Github but it turned out to
be a very superficial look because the schematics are only in
Kicad format.
I know Kicad is free but the time to install it and get to know
it isn't.
It would be very helpful if you were also to present the
schematics as .pdf which I think pretty much everyone has a way of
reading.
Of course it's your project and your time and I am well aware
that I'm asking you to do something extra - I do think you would
attract more interest and maybe more useful comment.
Michael Kellett,
MK Electronics Ltd.,
Unit 4,
Greenlaw,
Castle Douglas,
DG7 2LH,
01556 506999
07968 111148
On 06/09/2022 23:13, Eli M wrote:
toggle quoted message
Show quoted text
Below are my accuracy test plots-- of course take everything with
a grain (or handful) of salt because I don't have a calibrated set
of resistors/capacitors, and I'm still a student learning the
field. The raw data is all in the github with the scripts to make
these plots (written in Julia).
The fact the board only has two shunt resistors is a major
limitation of the design for a general audience. I almost measure
components within 100m-10k range so 100 Ohm shunt does the job. I
figure anybody willing to populate a PCB and use a DAQ should know
the application well enough to pick the right resistors for the
job.?
My plan is to make a set of loads in shielded enclosures with BNC
connectors on each such that the connection is repeatable on
different meters. The Kelvin clips are a good start minimizing the
effect of contact resistance, but still end up being moved
changing the parasitic values, which is especially harmful to the
measurement at 100 kHz. Then I'd gladly send the loads to whoever
would like to test and there can be a level of certainty that
there are no connection errors. Also using low tempco resistors is
probably important for this. Now that I think of it, I'll probably
make a design shortly and start a new thread on the matter because
it is a bit tangential, and I think there are plenty of readers
who would have helpful insights on it.?
-Eli
1kHz resistor measurements:
10kHz resistor
measurements:
100kHz measurement:
Capacitors @ 10kHz: Ceramic
below 1μF, radial film 1μF and above
|
Re: Question about SOL(T) kits for VNA.
thanks Dave,
I knew you make professional kits, but they are far too expensive for my poor wallet. :-(
Claudio
|
Hi all,
I have 2 Q meters, a Boonton 260A and a Marconi TF1245A, both restored and working nicely and beautiful instruments. The Boonton coils fit the Marconi but the reverse is not the case. I want to be able to compare readings between the two so I m making an adaptor to allow Marconi coils to fit the Boonton. My question is, What is the thread used on the Boonton binding posts? I'm in Australia where obtaining US screws is not easy. I have a lathe and can make a thread but need to know the details. It's 28 TPI and just under 1/4" OD.
I also intend going on to the make a copy of the Marconi TJ230 test jig that allows higher value capacitors to be tested for series loss.
Any info gratefully accepted.
Thanks, Morris VK3DOC
|
Re: 10 MHz reference inputs
I eventually found a video distribution amp that did a good job, but the first one I used tried to do sync restoration, which made a pretty nasty mess of my 10MHz signal. Choose carefully and check the output!
|
Re: 10 MHz reference inputs
A standard (analogue) video distribution amplifier could be used to buffer your external 10MHz source. They are designed for 75Ω input and output impedance, have 10 isolated outputs and are designed to handle 1V pk-pk signals. Typical isolation between outputs is in the range 20 – 30dB. ?
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From: [email protected] <[email protected]> On Behalf Of david vanhorn
Sent: Wednesday, 7 September 2022 04:22
To: [email protected]
Subject: [Test Equipment Design & Construction] 10 MHz reference inputs? I'm fighting a problem with some signal generators and I thought this group might have some information I need. 1: For a "typical instrument" what level should the 10 MHz input be?? These SGs say NOTHING in the manual about that. 2: My past experience with older HP/Tek gear is that if you provide an input they use that, otherwise they use their internal. ? I've seen instruments that have 10MHz input and output connectors separately, but now I'm faced with a new twist, a single connector marked 10 MHz In/Out? These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed! This seems totally insane to me.? What I would expect is that the SG delivers no signal output, and to maybe display "NO REFERENCE" or some such, but NOT to automatically go back to internal (about 2 to 4 Hz off on these units) and to force that signal out onto the 10 MHz signal bus. I've thought up some workarounds but so far it's all pretty kludegy and inelegant.
|
Re: 10 MHz reference inputs
If you go by what HP's frequency counters expected/accepted, it's
roughly a volt rms, perhaps within a factor of 2. Some go as high as
5V, but that's not what's required -- it's what's tolerated. There
does not appear to be a fixed standard, but that range should put
you in the ballpark. Just remember that this information is worth
twice what you paid for it.
Good luck!
-- Cheers
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 11:22, david vanhorn wrote:
toggle quoted message
Show quoted text
I'm fighting a problem with some signal generators and I
thought this group might have some information I need.
?
1: For a "typical instrument" what level should the 10 MHz
input be?? These SGs say NOTHING in the manual about that.
?
2: My past experience with older HP/Tek gear is that if you
provide an input they use that, otherwise they use their
internal. ? I've seen instruments that have 10MHz input and
output connectors separately, but now I'm faced with a new
twist, a single connector marked 10 MHz In/Out? These units let
you manually select ext or internal, but if the ref goes away
for a moment, or the power is lost, the SG switches back to
internal without notifying you, AND forces it's internal 10 MHz
out on the cable, which distorts and beats against the 10 MHz
being supplied, potentially screwing up any other instruments on
that feed!
?
This seems totally insane to me.? What I would expect is that
the SG delivers no signal output, and to maybe display "NO
REFERENCE" or some such, but NOT to automatically go back to
internal (about 2 to 4 Hz off on these units) and to force that
signal out onto the 10 MHz signal bus.
?
I've thought up some workarounds but so far it's all pretty
kludegy and inelegant.
|
I'm fighting a problem with some signal generators and I thought this group might have some information I need.
?
1: For a "typical instrument" what level should the 10 MHz input be?? These SGs say NOTHING in the manual about that.
?
2: My past experience with older HP/Tek gear is that if you provide an input they use that, otherwise they use their internal. ? I've seen instruments that have 10MHz input and output connectors separately, but now I'm faced with a new twist, a single connector marked 10 MHz In/Out? These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed!
?
This seems totally insane to me.? What I would expect is that the SG delivers no signal output, and to maybe display "NO REFERENCE" or some such, but NOT to automatically go back to internal (about 2 to 4 Hz off on these units) and to force that signal out onto the 10 MHz signal bus.
?
I've thought up some workarounds but so far it's all pretty kludegy and inelegant.
|
Re: Open source impedance analyzer
Below are my accuracy test plots-- of course take everything with a grain (or handful) of salt because I don't have a calibrated set of resistors/capacitors, and I'm still a student learning the field. The raw data is all in the github with the scripts to make these plots (written in Julia). The fact the board only has two shunt resistors is a major limitation of the design for a general audience. I almost measure components within 100m-10k range so 100 Ohm shunt does the job. I figure anybody willing to populate a PCB and use a DAQ should know the application well enough to pick the right resistors for the job.? My plan is to make a set of loads in shielded enclosures with BNC connectors on each such that the connection is repeatable on different meters. The Kelvin clips are a good start minimizing the effect of contact resistance, but still end up being moved changing the parasitic values, which is especially harmful to the measurement at 100 kHz. Then I'd gladly send the loads to whoever would like to test and there can be a level of certainty that there are no connection errors. Also using low tempco resistors is probably important for this. Now that I think of it, I'll probably make a design shortly and start a new thread on the matter because it is a bit tangential, and I think there are plenty of readers who would have helpful insights on it.? -Eli 1kHz resistor measurements: 10kHz resistor measurements: 100kHz measurement: Capacitors @ 10kHz: Ceramic below 1μF, radial film 1μF and above
|
Re: Question about SOL(T) kits for VNA.
On Tue, Sep 6, 2022 at 06:46 AM, i2NDT Claudio wrote:
I bought a couple of miniVNA and both came with a male SOL kit.
now, whenever I want to measure a DUT, I need to use cables which are terminated with a male connector.
to calibrate the set up I need to use a barrel (double female) to connect the SOL connectors, but this way I increase the length of the cable by at least 1/2 of the length of the barrel!
maybe it's negligible using SMA connectors but with N connectors...I have a Radiall R161 705 barrel (I guess rated for 10GHz) which is 4,5 cm. long!
so, why do not use only female SOL kits?
thanks in advance for your answers!
73
de
i2NDT Claudio
VNA calibration kits are available with both male and female connectors - my company sells them. Specifically an SMA kit. Note the male and female standards. You do need both, but depending on budget, people will make do with less. Our basic 7 GHz VNA calibration kit, with no options, costs about the same as your miniVNA. Dave
|
Question about SOL(T) kits for VNA.
I bought a couple of miniVNA and both came with a male SOL kit.
now, whenever I want to measure a DUT, I need to use cables which are terminated with a male connector.
to calibrate the set up I need to use a barrel (double female) to connect the SOL connectors, but this way I increase the length of the cable by at least 1/2 of the length of the barrel!
maybe it's negligible using SMA connectors but with N connectors...I have a Radiall R161 705 barrel (I guess rated for 10GHz) which is 4,5 cm. long!
so, why do not use only female SOL kits?
thanks in advance for your answers!
73
de
i2NDT Claudio
|
Re: A stable and repeatable low value capacitance meter
On Tue, 6 Sept 2022 at 10:58, Kenneth Greenough via <g8beqglossop= [email protected]> wrote:
You've never heard of the Kelvin temperature scale ? or the 3rd law
of thermodynamics ? Named for the? work of William Thomson, 1st
Baron Kelvin.
?Ken G8BEQ
Tom was joking - he even put a smile
|
Re: A stable and repeatable low value capacitance meter
Hello,
a small video explaining the process (and a suboptimal but
working design for the HP 4262A) is here:
Tam
- - - - -
With best regards
Tam HANNA
Enjoy electronics? Join 13500 followers by visiting the Crazy Electronics Lab at
On 06.09.22 11:23, Pete_G4GJL wrote:
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Named after Lord Kelvin, British Scientist.
Pete
G4GJL
On Tue, Sep 6, 2022 at 10:02
AM Tom Lee < tomlee@...>
wrote:
It's not so much that there is a clip named Kelvin, but
that there's a thing called a Kelvin connection, in which
you drive the DUT with one pair of wires, but sense voltage
with a separate pair. This connection eliminates errors due
to voltage drop along the inevitable resistance/impedance of
the driving pair.
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 00:13, i2NDT Claudio via wrote:
thanks for all answers! I didn't know that the name of
those clips was "kelvin".
BTW i checked digikey for them and was shocked by their
prices! a set of 2 clips cabled to banana plugs was
about 200�!!!
Claudio
|
hello
I have this one
Working for normal price.
Not like profesional but for radioham are ok.
bye
matjaz
|
Re: A stable and repeatable low value capacitance meter
You've never heard of the Kelvin temperature scale ? or the 3rd law
of thermodynamics ? Named for the? work of William Thomson, 1st
Baron Kelvin.
?Ken G8BEQ
On 06/09/2022 10:29, Tom Lee wrote:
toggle quoted message
Show quoted text
Never heard of him.? :)
--Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 02:23, Pete_G4GJL wrote:
Named after Lord Kelvin, British Scientist.
Pete
G4GJL
On Tue, Sep 6, 2022 at 10:02
AM Tom Lee < tomlee@...>
wrote:
It's not so much that there is a clip named Kelvin,
but that there's a thing called a Kelvin connection, in
which you drive the DUT with one pair of wires, but sense
voltage with a separate pair. This connection eliminates
errors due to voltage drop along the inevitable
resistance/impedance of the driving pair.
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 00:13, i2NDT Claudio via wrote:
thanks for all answers! I didn't know that the name
of those clips was "kelvin".
BTW i checked digikey for them and was shocked by
their prices! a set of 2 clips cabled to banana plugs
was about 200�!!!
Claudio
|
Re: A stable and repeatable low value capacitance meter
thanks for all answers! I didn't know that the name of those clips was "kelvin".
BTW i checked digikey for them and was shocked by their prices! a set of 2 clips cabled to banana plugs was about 200�!!!
Claudio
BNC versions from Keysight would cost you over 1000 Euro
It’s worth reading about 4-terminal connections. Those clips are not the only way to make them, or even the most common way. For example, some meter shunts for measuring high currents use 4 terminals. Platinum resistance thermometers (typically Pt100) will have 4 wires to enable you to accurately determine the resistance of something, despite a long lead length.?
Dave.? -- 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
|
Re: A stable and repeatable low value capacitance meter
Never heard of him.? :)
--Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 02:23, Pete_G4GJL wrote:
toggle quoted message
Show quoted text
Named after Lord Kelvin, British Scientist.
Pete
G4GJL
On Tue, Sep 6, 2022 at 10:02
AM Tom Lee < tomlee@...>
wrote:
It's not so much that there is a clip named Kelvin, but
that there's a thing called a Kelvin connection, in which
you drive the DUT with one pair of wires, but sense voltage
with a separate pair. This connection eliminates errors due
to voltage drop along the inevitable resistance/impedance of
the driving pair.
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 00:13, i2NDT Claudio via wrote:
thanks for all answers! I didn't know that the name of
those clips was "kelvin".
BTW i checked digikey for them and was shocked by their
prices! a set of 2 clips cabled to banana plugs was
about 200�!!!
Claudio
|
Re: A stable and repeatable low value capacitance meter
Named after Lord Kelvin, British Scientist.
Pete G4GJL
On Tue, Sep 6, 2022 at 10:02 AM Tom Lee < tomlee@...> wrote:
It's not so much that there is a clip named Kelvin, but that there's
a thing called a Kelvin connection, in which you drive the DUT with
one pair of wires, but sense voltage with a separate pair. This
connection eliminates errors due to voltage drop along the
inevitable resistance/impedance of the driving pair.
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 00:13, i2NDT Claudio via
wrote:
thanks for all answers! I didn't know that the name of those
clips was "kelvin".
BTW i checked digikey for them and was shocked by their prices!
a set of 2 clips cabled to banana plugs was about 200�!!!
Claudio
|
Re: A stable and repeatable low value capacitance meter
It's not so much that there is a clip named Kelvin, but that there's
a thing called a Kelvin connection, in which you drive the DUT with
one pair of wires, but sense voltage with a separate pair. This
connection eliminates errors due to voltage drop along the
inevitable resistance/impedance of the driving pair.
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/6/2022 00:13, i2NDT Claudio via
groups.io wrote:
toggle quoted message
Show quoted text
thanks for all answers! I didn't know that the name of those
clips was "kelvin".
BTW i checked digikey for them and was shocked by their prices!
a set of 2 clips cabled to banana plugs was about 200�!!!
Claudio
|
Dr. David Kirkby, Kirkby Microwave Ltd
Pete_G4GJL