Yes thanks, I have started the cal process and it seems to be happy.

dan

?

From: [email protected] <[email protected]> On Behalf Of Harvey White
Sent: Monday, August 8, 2022 10:50 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

The real problem with the meters is the battery damage.? Go partway through the calibration procedure (just very rough), and see if the processor will store the cal constants.? If so, you're lucky.? I have one or two that do not store the cal constants and are of little current use.? All that I have are battery damaged.? The cal procedure adjusts (IIRC) the readings down, as the meter is designed to read high without calibration.?

The high voltage needed for the AC calibration is the one real problem in calibration.? Tek recommends the 5200 series calibrator with the AC amplifier needed to get to the high voltage.? I haven't solved that problem yet, but haven't needed it since none of mine are yet working.??

Harvey

?

On 8/8/2022 11:37 AM, dan.meeks222@... wrote:

Thanks Eric – yep when I got it, there was battery gom all over that part of the board. I got it up and running, but this meter, as you may know, doesn’t just come up and work when the cal coefficients have been lost. It’s way off, so a calibration is a must. I’ll keep my eyes open for one of those Flukes.

Dan

?

From: [email protected] <[email protected]> On Behalf Of Eric
Sent: Monday, August 8, 2022 10:25 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

Be on the lookout for a fluke 5200A and if possible the 5205 amplifier. These are currently my best AC standards in the lab. Also there is known issues on the DM5010 (battery damage on the processor board) just mentioning this if this has not be checked and corrected in this unit.

?

The High AC volts on the dial a frequency is some of the hard part of doing meters. I have run in to meters that need 2 or 3 different voltage and frequency combinations to get an alignment done.

?

Eric/Zen

?

From: [email protected] <[email protected]> On Behalf Of dan.meeks222@...
Sent: Monday, August 8, 2022 10:34 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have a DM5010 that I would love to calibrate. The difficult items in the cal procedure are 190V and 700V at 200Hz.

I have tried to string some standard 70V line audio transformers together and use an audio power amp, but it doesn’t seem to like that load and it disconnects. Haven’t tried anything else yet.

I have other good meters to use as my “standard” so I am thinking I don’t need a sophisticated calibrator. Not trying to get NBS traceability here, just a working meter.

I don’t even really need this meter… just want to complete the repair! I really should just try to sell it as-is maybe.

Thanks

Dan

?

From: [email protected] <[email protected]> On Behalf Of tgerbic
Sent: Monday, August 8, 2022 4:16 AM
To: [email protected]
Subject: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.? I have, for example, a bunch of Fluke bench multimeters I thought I would test/calibrate last year. Everything was easy till I hit the AC cal sections. An AC calibrator would be very useful to me as I have a lot of meters, many have high frequency ranges up to or beyond 1Mhz, that call for different frequencies and a wide range of voltages.

What I would expect would be a low distortion sinewave with calibrated voltages from millivolts to over 300V. Frequency might range from perhaps 10hz to 1Mhz. Not necessarily continuous frequency but a range of frequencies required by most test equipment for calibration. It would be convenient to have output voltages that were calibrated/selectable for RMS, average, peak and peak to peak to align with calibration procedures across a large variety of test equipment. This would just be selections to vary the sinewave amplitude and perhaps a peak selector. Ideally it would have a low source impedance such that on at least some ranges you could have a calibrated AC current source.?

I can think of several designs that would provide the functionality but really need to think this through and limit the features to a more targeted amount. I have done some preliminary investigations to determine what ranges and frequencies I need for most of my HP, Fluke, Heath, Instek, Simpson, and other brand multimeters.

I think this would solve a big hole in hobbyist metrology. DC voltage, DC current and resistance are pretty easy to setup on the average workbench and get pretty accurate results. Frequency is pretty easy as well with GPS disciplined oscillators. AC is harder to deal with. While equipment exists to purchase/repair, it is generally pretty expensive and may have a limited range of voltage or frequency, unless it is really expensive.? I suspect most of us end up kludging up a test setup to at least get some of the required voltages and frequencies, unfortunately skipping many combinations.

I would like to get some thoughts from others about how they do AC calibration outside of a rheostat/isolation transformer on a 50/60Hz power line, or a sinewave generator for low voltages.

From: [email protected] <[email protected]> On Behalf Of Harvey White
Sent: Monday, August 8, 2022 10:50 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

The real problem with the meters is the battery damage.? Go partway through the calibration procedure (just very rough), and see if the processor will store the cal constants.? If so, you're lucky.? I have one or two that do not store the cal constants and are of little current use.? All that I have are battery damaged.? The cal procedure adjusts (IIRC) the readings down, as the meter is designed to read high without calibration.?

The high voltage needed for the AC calibration is the one real problem in calibration.? Tek recommends the 5200 series calibrator with the AC amplifier needed to get to the high voltage.? I haven't solved that problem yet, but haven't needed it since none of mine are yet working.??

Harvey

?

Thanks Eric – yep when I got it, there was battery gom all over that part of the board. I got it up and running, but this meter, as you may know, doesn’t just come up and work when the cal coefficients have been lost. It’s way off, so a calibration is a must. I’ll keep my eyes open for one of those Flukes.

Dan

?

From: [email protected] <[email protected]> On Behalf Of Eric
Sent: Monday, August 8, 2022 10:25 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

Be on the lookout for a fluke 5200A and if possible the 5205 amplifier. These are currently my best AC standards in the lab. Also there is known issues on the DM5010 (battery damage on the processor board) just mentioning this if this has not be checked and corrected in this unit.

?

The High AC volts on the dial a frequency is some of the hard part of doing meters. I have run in to meters that need 2 or 3 different voltage and frequency combinations to get an alignment done.

?

Eric/Zen

?

From: [email protected] <[email protected]> On Behalf Of dan.meeks222@...
Sent: Monday, August 8, 2022 10:34 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have a DM5010 that I would love to calibrate. The difficult items in the cal procedure are 190V and 700V at 200Hz.

I have tried to string some standard 70V line audio transformers together and use an audio power amp, but it doesn’t seem to like that load and it disconnects. Haven’t tried anything else yet.

I have other good meters to use as my “standard” so I am thinking I don’t need a sophisticated calibrator. Not trying to get NBS traceability here, just a working meter.

I don’t even really need this meter… just want to complete the repair! I really should just try to sell it as-is maybe.

Thanks

Dan

?

From: [email protected] <[email protected]> On Behalf Of tgerbic
Sent: Monday, August 8, 2022 4:16 AM
To: [email protected]
Subject: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.? I have, for example, a bunch of Fluke bench multimeters I thought I would test/calibrate last year. Everything was easy till I hit the AC cal sections. An AC calibrator would be very useful to me as I have a lot of meters, many have high frequency ranges up to or beyond 1Mhz, that call for different frequencies and a wide range of voltages.

What I would expect would be a low distortion sinewave with calibrated voltages from millivolts to over 300V. Frequency might range from perhaps 10hz to 1Mhz. Not necessarily continuous frequency but a range of frequencies required by most test equipment for calibration. It would be convenient to have output voltages that were calibrated/selectable for RMS, average, peak and peak to peak to align with calibration procedures across a large variety of test equipment. This would just be selections to vary the sinewave amplitude and perhaps a peak selector. Ideally it would have a low source impedance such that on at least some ranges you could have a calibrated AC current source.?

I can think of several designs that would provide the functionality but really need to think this through and limit the features to a more targeted amount. I have done some preliminary investigations to determine what ranges and frequencies I need for most of my HP, Fluke, Heath, Instek, Simpson, and other brand multimeters.

I think this would solve a big hole in hobbyist metrology. DC voltage, DC current and resistance are pretty easy to setup on the average workbench and get pretty accurate results. Frequency is pretty easy as well with GPS disciplined oscillators. AC is harder to deal with. While equipment exists to purchase/repair, it is generally pretty expensive and may have a limited range of voltage or frequency, unless it is really expensive.? I suspect most of us end up kludging up a test setup to at least get some of the required voltages and frequencies, unfortunately skipping many combinations.

I would like to get some thoughts from others about how they do AC calibration outside of a rheostat/isolation transformer on a 50/60Hz power line, or a sinewave generator for low voltages.

Thanks Eric – yep when I got it, there was battery gom all over that part of the board. I got it up and running, but this meter, as you may know, doesn’t just come up and work when the cal coefficients have been lost. It’s way off, so a calibration is a must. I’ll keep my eyes open for one of those Flukes.

Dan

?

From: [email protected] <[email protected]> On Behalf Of Eric
Sent: Monday, August 8, 2022 10:25 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

Be on the lookout for a fluke 5200A and if possible the 5205 amplifier. These are currently my best AC standards in the lab. Also there is known issues on the DM5010 (battery damage on the processor board) just mentioning this if this has not be checked and corrected in this unit.

?

The High AC volts on the dial a frequency is some of the hard part of doing meters. I have run in to meters that need 2 or 3 different voltage and frequency combinations to get an alignment done.

?

Eric/Zen

?

From: [email protected] <[email protected]> On Behalf Of dan.meeks222@...
Sent: Monday, August 8, 2022 10:34 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have a DM5010 that I would love to calibrate. The difficult items in the cal procedure are 190V and 700V at 200Hz.

I have tried to string some standard 70V line audio transformers together and use an audio power amp, but it doesn’t seem to like that load and it disconnects. Haven’t tried anything else yet.

I have other good meters to use as my “standard” so I am thinking I don’t need a sophisticated calibrator. Not trying to get NBS traceability here, just a working meter.

I don’t even really need this meter… just want to complete the repair! I really should just try to sell it as-is maybe.

Thanks

Dan

?

From: [email protected] <[email protected]> On Behalf Of tgerbic
Sent: Monday, August 8, 2022 4:16 AM
To: [email protected]
Subject: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.? I have, for example, a bunch of Fluke bench multimeters I thought I would test/calibrate last year. Everything was easy till I hit the AC cal sections. An AC calibrator would be very useful to me as I have a lot of meters, many have high frequency ranges up to or beyond 1Mhz, that call for different frequencies and a wide range of voltages.

What I would expect would be a low distortion sinewave with calibrated voltages from millivolts to over 300V. Frequency might range from perhaps 10hz to 1Mhz. Not necessarily continuous frequency but a range of frequencies required by most test equipment for calibration. It would be convenient to have output voltages that were calibrated/selectable for RMS, average, peak and peak to peak to align with calibration procedures across a large variety of test equipment. This would just be selections to vary the sinewave amplitude and perhaps a peak selector. Ideally it would have a low source impedance such that on at least some ranges you could have a calibrated AC current source.?

I can think of several designs that would provide the functionality but really need to think this through and limit the features to a more targeted amount. I have done some preliminary investigations to determine what ranges and frequencies I need for most of my HP, Fluke, Heath, Instek, Simpson, and other brand multimeters.

I think this would solve a big hole in hobbyist metrology. DC voltage, DC current and resistance are pretty easy to setup on the average workbench and get pretty accurate results. Frequency is pretty easy as well with GPS disciplined oscillators. AC is harder to deal with. While equipment exists to purchase/repair, it is generally pretty expensive and may have a limited range of voltage or frequency, unless it is really expensive.? I suspect most of us end up kludging up a test setup to at least get some of the required voltages and frequencies, unfortunately skipping many combinations.

I would like to get some thoughts from others about how they do AC calibration outside of a rheostat/isolation transformer on a 50/60Hz power line, or a sinewave generator for low voltages.

From: [email protected] <[email protected]> On Behalf Of Eric
Sent: Monday, August 8, 2022 10:25 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

Be on the lookout for a fluke 5200A and if possible the 5205 amplifier. These are currently my best AC standards in the lab. Also there is known issues on the DM5010 (battery damage on the processor board) just mentioning this if this has not be checked and corrected in this unit.

?

The High AC volts on the dial a frequency is some of the hard part of doing meters. I have run in to meters that need 2 or 3 different voltage and frequency combinations to get an alignment done.

?

Eric/Zen

?

?

I have a DM5010 that I would love to calibrate. The difficult items in the cal procedure are 190V and 700V at 200Hz.

I have tried to string some standard 70V line audio transformers together and use an audio power amp, but it doesn’t seem to like that load and it disconnects. Haven’t tried anything else yet.

I have other good meters to use as my “standard” so I am thinking I don’t need a sophisticated calibrator. Not trying to get NBS traceability here, just a working meter.

I don’t even really need this meter… just want to complete the repair! I really should just try to sell it as-is maybe.

Thanks

Dan

?

?

I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.? I have, for example, a bunch of Fluke bench multimeters I thought I would test/calibrate last year. Everything was easy till I hit the AC cal sections. An AC calibrator would be very useful to me as I have a lot of meters, many have high frequency ranges up to or beyond 1Mhz, that call for different frequencies and a wide range of voltages.

What I would expect would be a low distortion sinewave with calibrated voltages from millivolts to over 300V. Frequency might range from perhaps 10hz to 1Mhz. Not necessarily continuous frequency but a range of frequencies required by most test equipment for calibration. It would be convenient to have output voltages that were calibrated/selectable for RMS, average, peak and peak to peak to align with calibration procedures across a large variety of test equipment. This would just be selections to vary the sinewave amplitude and perhaps a peak selector. Ideally it would have a low source impedance such that on at least some ranges you could have a calibrated AC current source.?

I can think of several designs that would provide the functionality but really need to think this through and limit the features to a more targeted amount. I have done some preliminary investigations to determine what ranges and frequencies I need for most of my HP, Fluke, Heath, Instek, Simpson, and other brand multimeters.

I think this would solve a big hole in hobbyist metrology. DC voltage, DC current and resistance are pretty easy to setup on the average workbench and get pretty accurate results. Frequency is pretty easy as well with GPS disciplined oscillators. AC is harder to deal with. While equipment exists to purchase/repair, it is generally pretty expensive and may have a limited range of voltage or frequency, unless it is really expensive.? I suspect most of us end up kludging up a test setup to at least get some of the required voltages and frequencies, unfortunately skipping many combinations.

I would like to get some thoughts from others about how they do AC calibration outside of a rheostat/isolation transformer on a 50/60Hz power line, or a sinewave generator for low voltages.

From: [email protected] <[email protected]> On Behalf Of dan.meeks222@...
Sent: Monday, August 8, 2022 10:34 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have a DM5010 that I would love to calibrate. The difficult items in the cal procedure are 190V and 700V at 200Hz.

I have tried to string some standard 70V line audio transformers together and use an audio power amp, but it doesn’t seem to like that load and it disconnects. Haven’t tried anything else yet.

I have other good meters to use as my “standard” so I am thinking I don’t need a sophisticated calibrator. Not trying to get NBS traceability here, just a working meter.

I don’t even really need this meter… just want to complete the repair! I really should just try to sell it as-is maybe.

Thanks

Dan

?

?

I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.? I have, for example, a bunch of Fluke bench multimeters I thought I would test/calibrate last year. Everything was easy till I hit the AC cal sections. An AC calibrator would be very useful to me as I have a lot of meters, many have high frequency ranges up to or beyond 1Mhz, that call for different frequencies and a wide range of voltages.

What I would expect would be a low distortion sinewave with calibrated voltages from millivolts to over 300V. Frequency might range from perhaps 10hz to 1Mhz. Not necessarily continuous frequency but a range of frequencies required by most test equipment for calibration. It would be convenient to have output voltages that were calibrated/selectable for RMS, average, peak and peak to peak to align with calibration procedures across a large variety of test equipment. This would just be selections to vary the sinewave amplitude and perhaps a peak selector. Ideally it would have a low source impedance such that on at least some ranges you could have a calibrated AC current source.?

I can think of several designs that would provide the functionality but really need to think this through and limit the features to a more targeted amount. I have done some preliminary investigations to determine what ranges and frequencies I need for most of my HP, Fluke, Heath, Instek, Simpson, and other brand multimeters.

I think this would solve a big hole in hobbyist metrology. DC voltage, DC current and resistance are pretty easy to setup on the average workbench and get pretty accurate results. Frequency is pretty easy as well with GPS disciplined oscillators. AC is harder to deal with. While equipment exists to purchase/repair, it is generally pretty expensive and may have a limited range of voltage or frequency, unless it is really expensive.? I suspect most of us end up kludging up a test setup to at least get some of the required voltages and frequencies, unfortunately skipping many combinations.

I would like to get some thoughts from others about how they do AC calibration outside of a rheostat/isolation transformer on a 50/60Hz power line, or a sinewave generator for low voltages.

From: [email protected] <[email protected]> On Behalf Of tgerbic
Sent: Monday, August 8, 2022 4:16 AM
To: [email protected]
Subject: [Test Equipment Design & Construction] AC Voltage Calibrator, home built

?

I have lots of equipment to do what I would call hobby level (non-NIST) equipment calibration. Perhaps quite a few of us can say the same but I think the one area of weakness for most of us is a variable frequency, variable AC voltage source.? I have, for example, a bunch of Fluke bench multimeters I thought I would test/calibrate last year. Everything was easy till I hit the AC cal sections. An AC calibrator would be very useful to me as I have a lot of meters, many have high frequency ranges up to or beyond 1Mhz, that call for different frequencies and a wide range of voltages.

What I would expect would be a low distortion sinewave with calibrated voltages from millivolts to over 300V. Frequency might range from perhaps 10hz to 1Mhz. Not necessarily continuous frequency but a range of frequencies required by most test equipment for calibration. It would be convenient to have output voltages that were calibrated/selectable for RMS, average, peak and peak to peak to align with calibration procedures across a large variety of test equipment. This would just be selections to vary the sinewave amplitude and perhaps a peak selector. Ideally it would have a low source impedance such that on at least some ranges you could have a calibrated AC current source.?

I can think of several designs that would provide the functionality but really need to think this through and limit the features to a more targeted amount. I have done some preliminary investigations to determine what ranges and frequencies I need for most of my HP, Fluke, Heath, Instek, Simpson, and other brand multimeters.

I think this would solve a big hole in hobbyist metrology. DC voltage, DC current and resistance are pretty easy to setup on the average workbench and get pretty accurate results. Frequency is pretty easy as well with GPS disciplined oscillators. AC is harder to deal with. While equipment exists to purchase/repair, it is generally pretty expensive and may have a limited range of voltage or frequency, unless it is really expensive.? I suspect most of us end up kludging up a test setup to at least get some of the required voltages and frequencies, unfortunately skipping many combinations.

I would like to get some thoughts from others about how they do AC calibration outside of a rheostat/isolation transformer on a 50/60Hz power line, or a sinewave generator for low voltages.

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of G8HUL
Sent: 08 August 2022 08:47
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Making a Q-meter /

I seem to recall that most of the R&S LCR meters also measured Q, can't recall the tolerance on the measurement.

73
Jeff G8HUL

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of jfphp via groups.io
Sent: 07 August 2022 15:18
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Making a Q-meter /

I am not at home.When back I will give more details (catalog 1970 lf I remember)





On Sunday, August 7, 2022 at 03:16:30 PM GMT+2, Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@...> wrote:


Someone suggested Rohde and Schwarz made Q-meters, but a Google did not get me anything useful. I asked on an R&S group and got the following from someone. He gives the German name for the Q-meter ( "Güte-Messger?t"). I don't speak German, so I can't glean much from anything from R&S.

===


An example is the R&S QDM, a Q-meter for inductors:
.

According to this document:
,
the QDM is from 1970.

An even older one is the model RVQ, one is currently on German ebay:
.

There also was a model QVH:
, a user manual is
here: .

You may be able to find more by googling for "Gütefaktormessger?t" or "Güte-Messger?t" (Q-meter in German).



Dr David Kirkby Ph.D
Email: drkirkby@... <mailto:drkirkby@...> Web:
Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100) Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT.






On Thu, 4 Aug 2022 at 09:19, Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@... <mailto:drkirkby@...> > wrote:


I am looking at the possibility of making a Q meter for the frequency range 1.5 MHz to 150 MHz. One common way to do this is to inject a voltage from a LOW impedance source, into a series tuned circuit, then measure the voltage developed across the tuned circuit with a high input impedance voltmeter. The Q is the ratio of those two voltages.


Designs for Q meters usually include an oscillator, but I don’t think I will bother with that as I can easily use a signal generator.


One design appeared in Practical Wireless in the November 1978 issue. I stuck a copy of that in a sub-directory for Q measurements in the files section of the forum

/g/Test-Equipment-Design-Construction/files/Q-factor%20%28Q%20is%20the%20inverse%20of%20dissipation%20factor%20DF%29. </g/Test-Equipment-Design-Construction/files/Q-factor%20%28Q%20is%20the%20inverse%20of%20dissipation%20factor%20DF%29.>

There are two problems I see with that design

1) The meter has measurement ranges of only 0-20 and 0-100, but many inductors have Q’s much higher than 100. The HP 4342A can measure Qs from 5 to 1000. The old Boonton 160-A measures Q up to 640 (from memory).

2) The output impedance of source is too high - it is approximately 2 ohm on the Q=0-20 range and 10.2 ohm on the Q=0-100 range.

Can anyone think of a way of turning a signal generator to have an output impedance of 1 milli ohm? I think I have a 5 W Minicircuits amplifier around, so I can afford to waste a bit in heat. But it is not practical to put 50 ohm in series with 1 milli ohm to terminate the amplifier in the required 50 ohm. I will have so little voltage left, it will be difficult to measure the output voltage, even though it’s multipled by the Q of the coil.

A step-down transformer seems the most obvious way, but that requires a turns ratio of sqrt(50000)=224. Even with a single turn on the secondary, there will be too many turns on the primary for this to work at 150 MHz.



I have not yet looked at the HP 4343A meter service manual. That will probably give me some ideas.

I suspect the answer is to not try to get such a low output impedance, accept that the voltage generated across the LC combination will be less than the Q, and correct for that in software.

Any other thoughts?


PS, Does anyone have any documentation, apart from the user manual, on the HP 42851A Q-adapter, which is used with the HP/Agilent 4285A Precision LCR meter?

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of jfphp via groups.io
Sent: 07 August 2022 15:18
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Making a Q-meter /

I am not at home.When back I will give more details (catalog 1970 lf I remember)





On Sunday, August 7, 2022 at 03:16:30 PM GMT+2, Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@...> wrote:


Someone suggested Rohde and Schwarz made Q-meters, but a Google did not get me anything useful. I asked on an R&S group and got the following from someone. He gives the German name for the Q-meter ( "Güte-Messger?t"). I don't speak German, so I can't glean much from anything from R&S.

===


An example is the R&S QDM, a Q-meter for inductors:
.

According to this document:
,
the QDM is from 1970.

An even older one is the model RVQ, one is currently on German ebay:
.

There also was a model QVH:
, a user manual is
here: .

You may be able to find more by googling for "Gütefaktormessger?t" or "Güte-Messger?t" (Q-meter in German).



Dr David Kirkby Ph.D
Email: drkirkby@... <mailto:drkirkby@...> Web:
Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100) Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT.






On Thu, 4 Aug 2022 at 09:19, Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@... <mailto:drkirkby@...> > wrote:


I am looking at the possibility of making a Q meter for the frequency range 1.5 MHz to 150 MHz. One common way to do this is to inject a voltage from a LOW impedance source, into a series tuned circuit, then measure the voltage developed across the tuned circuit with a high input impedance voltmeter. The Q is the ratio of those two voltages.


Designs for Q meters usually include an oscillator, but I don’t think I will bother with that as I can easily use a signal generator.


One design appeared in Practical Wireless in the November 1978 issue. I stuck a copy of that in a sub-directory for Q measurements in the files section of the forum

/g/Test-Equipment-Design-Construction/files/Q-factor%20%28Q%20is%20the%20inverse%20of%20dissipation%20factor%20DF%29. </g/Test-Equipment-Design-Construction/files/Q-factor%20%28Q%20is%20the%20inverse%20of%20dissipation%20factor%20DF%29.>

There are two problems I see with that design

1) The meter has measurement ranges of only 0-20 and 0-100, but many inductors have Q’s much higher than 100. The HP 4342A can measure Qs from 5 to 1000. The old Boonton 160-A measures Q up to 640 (from memory).

2) The output impedance of source is too high - it is approximately 2 ohm on the Q=0-20 range and 10.2 ohm on the Q=0-100 range.

Can anyone think of a way of turning a signal generator to have an output impedance of 1 milli ohm? I think I have a 5 W Minicircuits amplifier around, so I can afford to waste a bit in heat. But it is not practical to put 50 ohm in series with 1 milli ohm to terminate the amplifier in the required 50 ohm. I will have so little voltage left, it will be difficult to measure the output voltage, even though it’s multipled by the Q of the coil.

A step-down transformer seems the most obvious way, but that requires a turns ratio of sqrt(50000)=224. Even with a single turn on the secondary, there will be too many turns on the primary for this to work at 150 MHz.



I have not yet looked at the HP 4343A meter service manual. That will probably give me some ideas.

I suspect the answer is to not try to get such a low output impedance, accept that the voltage generated across the LC combination will be less than the Q, and correct for that in software.

Any other thoughts?


PS, Does anyone have any documentation, apart from the user manual, on the HP 42851A Q-adapter, which is used with the HP/Agilent 4285A Precision LCR meter?