Keithley DMM7510 7.5-Digit Multimeter Review, Teardown & Experiments

[Hugoneus]

You can watch the video here: [1 Hour & 17 Minutes]
youtu.be/yT7aOK0q17Q

More videos at The Signal Path:
http://www.TheSignalPath.com

[TiN]

Great review, as always from you, specially flame conductivity experiment. Did not think frame deflection by electrons could be so visible with just few kV.

One thing I'd ask for, if possible, to get some zero samples DCV data, with different NPLC and ranges. I'd like to add DMM7510 into comparison with older Keithley's, as I do own already 2000, few 2001, 2002. You can check details in thread here.

If it's really lower noise than 8.5 DMM like Keithley state on their brochure, i'd consider selling few my meters and getting 7510.   

P.S. no cats? Woa...
P.P.S. just saw your reply @youtube. Thanks!

[Cliff Matthews]

Excellent and fascinating - Thanks! (Congrats! I notice the channel is about to pass the 25,000 subscriber milestone).
As a side note, what do you call that black smooth plastic pointer he uses? I'd like to buy a set.

I used to have a set of soft nylon adjustment tools (from back in the day) for TV. Anything more rigid I can trust?

[Hugoneus]

One thing I'd ask for, if possible, to get some zero samples DCV data, with different NPLC and ranges. I'd like to add DMM7510 into comparison with older Keithley's, as I do own already 2000, few 2001, 2002. You can check details in thread here.
If it's really lower noise than 8.5 DMM like Keithley state on their brochure, i'd consider selling few my meters and getting 7510.   
P.S. no cats? Woa...
P.P.S. just saw your reply @youtube. Thanks!

No problem, I will capture this data for you.

[German_EE]

Test equipment porn  I'd love to have one of those on my bench but as there's no chance of this I shall just have to look at the pictures. Given that the unit works down to below a millionth of a volt your reluctance to do a full teardown is understandable, if I was Keithley I'd calibrate the units electronically after all of the covers were on and the insides were stable.

That fan is weird though.

[dr.diesel]

That fan is weird though.

That is pretty bizarre, interesting.  I wonder if maybe it's only for agitating the volume inside the device, stuff not covered with protective shielding?  I'd find it very unusual of Keithley to rush it out, not installing the vent through the bottom if that was truly the need.

[HKJ]

That fan is weird though.

The fan may not be optimally placed for high airflow. There is about 5mm between the pcb and the cover and the cover do have a couple of small slits (About 50) for the air to pass through, but they are placed some distance from the fan.

[mcinque]

The video is totally porn.   

I've only a question: why do you use that killer tungsten carbide point pen near that instruments?!?  I fear you can scratch that jewels every time that damn sharp and hard point pass near the displays!! 

 

[Dr. Frank]

Sorry, but    for that video!

This instrument, as others, is able to make fast measurements, NPLC 1 or even faster, and also updates the display at that 60Hz rate.. So that's really no big deal, and no special sign of quality.

Instead, you should have always selected a longer integration time, NPLC 10 and higher, especially when the measurements were getting more sensitive, to demonstrate the accuracy and stability of this Keithley (!)  instrument, especially at low currents, for exapmles.

The way you did it, simply made me nervous, just like the flickering display.
Sorry, couldn't stand it any more, had to stop your video this time in the middle.

What i also missed, was a sophisticated analysis of the most important circuitry elements.

Dave did that much better before!

Frank

[dadler]

Wow, 1M samples/sec digitize capability.

Kinda makes me re-think the $650 digitize+memory (crippled-enabled) options for my 34465A. This only takes the 34465A from 5k to 50k samples/sec. And that brings the cost of the 6.5 digit meter to over $2k. Compared to the 34470A, the Keithley seems like a much more capable piece of kit for the price.

[Hugoneus]

Sorry, but    for that video!
This instrument, as others, is able to make fast measurements, NPLC 1 or even faster, and also updates the display at that 60Hz rate.. So that's really no big deal, and no special sign of quality.
Instead, you should have always selected a longer integration time, NPLC 10 and higher, especially when the measurements were getting more sensitive, to demonstrate the accuracy and stability of this Keithley (!)  instrument, especially at low currents, for exapmles.
The way you did it, simply made me nervous, just like the flickering display.
Sorry, couldn't stand it any more, had to stop your video this time in the middle.
What i also missed, was a sophisticated analysis of the most important circuitry elements.
Dave did that much better before!
Frank

Did you miss the part where I set the NPLC to 5 for every sensitive measurement that I did? So because you didn't see a NPLC set to 10 as opposed to 5 it made you so nervous that you had to stop watching the video half way? I definitely didn't intend to cause you so much discomfort.

Either way, I will be recording the NPLC of 10 for TiN who requested the noise floor measurement of the instrument. I hope that you can find that useful.

[Dr. Frank]

Wow, 1M samples/sec digitize capability.

Kinda makes me re-think the $650 digitize+memory (crippled-enabled) options for my 34465A. This only takes the 34465A from 5k to 50k samples/sec. And that brings the cost of the 6.5 digit meter to over $2k. Compared to the 34470A, the Keithley seems like a much more capable piece of kit for the price.

Well, it even costs much more than the 34470A, which I also wouldn't buy.

Both are overpriced, because if you look into their specs, they are nearly on par, but the stability is far away  from real 7 1/2 digit performance, i.e. linearity, stabilities, etc.

The Keithley features an additional 1MS, 18bit ADC, afair, as Keysight always uses its regular Multislope IV ADC.
So that's also no big deal.. and what are the SNR figures of this ADC?

For real good performance, a used 3458A, lower price,  probably might be still better.

Frank

[Dr. Frank]

Sorry, but    for that video!
This instrument, as others, is able to make fast measurements, NPLC 1 or even faster, and also updates the display at that 60Hz rate.. So that's really no big deal, and no special sign of quality.
Instead, you should have always selected a longer integration time, NPLC 10 and higher, especially when the measurements were getting more sensitive, to demonstrate the accuracy and stability of this Keithley (!)  instrument, especially at low currents, for exapmles.
The way you did it, simply made me nervous, just like the flickering display.
Sorry, couldn't stand it any more, had to stop your video this time in the middle.
What i also missed, was a sophisticated analysis of the most important circuitry elements.
Dave did that much better before!
Frank

Did you miss the part where I set the NPLC to 5 for every sensitive measurement that I did? So because you didn't see a NPLC set to 10 as opposed to 5 it made you so nervous that you had to watch the video half way?

Either way, I will be recording the NPLC of 10 for TiN who requested the noise floor measurement of the instrument.

Sorry, in the beginning you emphasized this fast update rate so much, that I really wondered, what you want to tell us about this simple setting.. Other instruments simply have a default of NPLC 10.

For sure I did see, that you have set NPLC 5, but sorry, for such delicate measurements, like 100nV or 10nV resolution, or 1µA and 100pA, there is enough noise "in the air", as you also ingenuously demonstrated, that these measurements urgently needed averaging times of NPLC 50 or more..

Be honest, please, have you really been able to read a stable result from that flickering display?
Maybe I'm already a little bit slow..

It would have been a good demonstration of good  measurement techniques, to reduce the rate further, and get the pA stable to the last digit, which might be well possible, as Keithley Instruments just stand for that.

Maybe a bit more shielding or guarding, and it would have been a real instructional and good video.

Frank

[Hugoneus]

...
Maybe a bit more shielding or guarding, and it would have been a real instructional video.

This is not an instructional video. It is a product review. I am limited by time to show a general overview of the instrument and there is no way to please everyone. I will do videos about sensitive measurements (in fact I actually have done that) some other time. The instrument has a specification page and calibration which is backed up by Keithley. But I appreciate the feedback and will incorporate it in my future reviews.

For this video, there is only so much that I could do, after all my lab assistant is a cat.

[HKJ]

With NLPC there is significant differences:
The Keithley always start with 1 NLPC, Keysight stars with 10 NLPC
The Keithley is also much slower than Keysight when running 10 NLPC

[Hugoneus]

With NLPC there is significant differences:
The Keithley always start with 1 NLPC, Keysight stars with 10 NLPC
The Keithley is also much slower than Keysight when running 10 NLPC

Why would that be? The aperture should be a linear function of NPLC. Do you have more information on this?

[Hugoneus]

By the way, from the DMM user manual:

The Model DMM7510 has a nonlinear shape for its speed versus noise characteristics. The Model
DMM7510 is optimized for the 1 PLC to 5 PLC reading rate. At these rates (lowest noise region in
graph), the Model DMM7510 will make corrections for its own internal drift and will still be fast enough
to settle a step response of less than 100 ms.

[HKJ]

With NLPC there is significant differences:
The Keithley always start with 1 NLPC, Keysight stars with 10 NLPC
The Keithley is also much slower than Keysight when running 10 NLPC

Why would that be? The aperture should be a linear function of NPLC. Do you have more information on this?

The Keithley do more measurements each cycle (Some zero and calibration measurements), I believe there is something in the manual about it.

Looking at the 34470A and 7510 I would say 4 NLPC on Keithley is about same speed as 10 NLPC Keysight.

[Lukas]

Great video as always

One UI issue I noticed: When entering values like 10nA, you have to type 1-0-n-Enter. On most other gear I've used, entering the SI prefix also terminates the input. Maybe that's an UI issue Keithley should know about.

I'm wondering whether the frequency measurement is done in hardware using a comparator or if they are doing an FFT of the digitized data to find the peak frequency. I guess that they're using a comparator, since the ADC should have no problem at digitizing a 1kHz 10mV signal.

[HKJ]

From the manual:
[:SENSe[1]]:<function>:AZERo[:STATe]

To ensure the accuracy of readings, the instrument must periodically get new measurements of its
internal ground and voltage reference. The time interval between updates to these reference
measurements is determined by the integration aperture that is being used for measurements. The
Model DMM7510 uses separate reference and zero measurements for each aperture.
By default, the instrument automatically checks these reference measurements whenever a signal
measurement is made.
The time to make the reference measurements is in addition to the normal measurement time. If
timing is critical, you can disable autozero to avoid this time penalty.
When autozero is set to off, the instrument may gradually drift out of specification. To minimize the
drift, you can send the once command to make a reference and zero measurement immediately
before a test sequence.
For AC voltage and AC current measurements where the detector bandwidth is set to 3 Hz or 30 Hz,
autozero is set on and cannot be changed.


-------------
There are a few other settings that will affect measurement speed like the "Delay" and "Line sync" setting.

[tec5c]

...after all my lab assistant is a cat.

 

[HighVoltage]

Very nice review and experiments, I really liked it.

I have made a few low current measurements with my Keysight 34470A, using the Keithley 2450 as the current source.

When you make the additional measurements for TiN, may I ask you do do a few additional measurements on a low DC current:
- Please set the 2450 to 1.0 nA DC current
- Please measure this current with the 7510 DMM in 10 NPLC and 100 NPLC settings
- If you have the time, may be capture the data with the fast digitizer mode as well.

May be you can make the data available as a CSV file and a few screen shot pictures of the statistics.
This would be a great comparison to the 34470A and I will make my measurements available as well.
Thank you.

[dr.diesel]

- Please set the 2450 to nA DC current and

Did you forget the current value? 

[HighVoltage]

Did you forget the current value?

Thank you,
It was suppose to be 1.0 nA

[Hugoneus]

Did you forget the current value?

Thank you,
It was suppose to be 1.0 nA

Ok, I did this measurement with 5 NPLC in the video. Did you also see the plot I posted in this thread about the DMM noise as a function of the NPLC?

[HighVoltage]

Ok, I did this measurement with 5 NPLC in the video. Did you also see the plot I posted in this thread about the DMM noise as a function of the NPLC?

Yes, I saw that and would put this in to consideration during the analysis.
Would be great, if you could repeat this measurement at 5, 10 and 100 NPLC and store the data as .CSV and may make a visual screen shot of the statistical analysis.

Thanks

[dr.diesel]

^ I could do the same for the K2450/K2010, but IIRC the K2010 has a max of 10PLC.

[HighVoltage]

^ I could do the same for the K2450/K2010, but IIRC the K2010 has a max of 10PLC.

Yes, please this way we get some good data comparison on 7 1/2 digit meters.

[Vgkid]

Thanks for the review, the experiments were the most interesting part.

[KedasProbe]

By the way, from the DMM user manual:

The Model DMM7510 has a nonlinear shape for its speed versus noise characteristics. The Model
DMM7510 is optimized for the 1 PLC to 5 PLC reading rate. At these rates (lowest noise region in
graph), the Model DMM7510 will make corrections for its own internal drift and will still be fast enough
to settle a step response of less than 100 ms.

I don't really understand what this graph means.
Does this mean 100PLC is worse than 1PLC then what is the point of having 100PLC?
I assume not, but what does it mean, that a change from 1PLC to 10PLC will be a lower improvement than what you mathematically expect?

Are 10 x 1PLC better than 1 x 10PLC?

[Dr. Frank]

Dear Shahriar,

at that point, I just wanted  to emphasize, that I really enjoy your other videos about scopes and other HF instruments.. that's always a great pleasure!

In this case anyhow, it would really be very interesting, if you please would measure the noise performance for different NPLCs, from 0.01 to 100, or so, as proposed by xdev already.

I can really not understand, why the noise should go up for NPLC >5, and why Keithley did not specify that range .. there's something fishy. Compare that to every other DMM, especially the 3458A, which noise is on the same order of magnitude , but I suppose to be still much better (decreasing numbers) towards NPLC 100.

The old Keithley 8 1/2 DMM is nearly a magnitude worse in terms of stability and noise , I still hope that Keithley improved in that category.

regards Frank

[dr.diesel]

^ I could do the same for the K2450/K2010, but IIRC the K2010 has a max of 10PLC.

Yes, please this way we get some good data comparison on 7 1/2 digit meters.

I didn't see much use in letting it run for very long!  If this was not your intent, please let me know.

(forum doesn't allow for an .ods file, converted to .xls, looks good on my end)

[nfmax]

By the way, from the DMM user manual:

The Model DMM7510 has a nonlinear shape for its speed versus noise characteristics. The Model
DMM7510 is optimized for the 1 PLC to 5 PLC reading rate. At these rates (lowest noise region in
graph), the Model DMM7510 will make corrections for its own internal drift and will still be fast enough
to settle a step response of less than 100 ms.

That plot looks a bit like an Allan variance plot, showing the transition from white-noise behaviour at short averaging times, to drift at longer times. I wonder how they measured it? If that is the case, it looks like the Keithley ADC cannot (fully) compensate for drift that occurs during the integration period. Is there any chance of collecting data for an Allan variance analysis covering the entire range of integration times, ideally comparing results with the Keysight/HP's?

[HighVoltage]

^ I could do the same for the K2450/K2010, but IIRC the K2010 has a max of 10PLC.

Yes, please this way we get some good data comparison on 7 1/2 digit meters.

I didn't see much use in letting it run for very long!  If this was not your intent, please let me know.

(forum doesn't allow for an .ods file, converted to .xls, looks good on my end)

Thank you for the data, but something is badly wrong
May be a wrong connection or the output not enabled and this is just noise?
Hmmm...

Max value in your data is +3.03 E-9
Min value  in your data is -6.93 E-9

It should be very stable around 1.00 E-9

[dr.diesel]

The K2010 lowest current range is 10mA.  Same connection, if I set 1uA it's pretty solid, varies a few counts. 

At 1nA it's just noise.

[HighVoltage]

The K2010 lowest current range is 10mA.  Same connection, if I set 1uA it's pretty solid, varies a few counts. 
At 1nA it's just noise.

Ahh, I see. Sorry I did not study the Keithley 2010 datasheet.
Then it is not possible to make this measurement.
Thanks anyways.

[TiN]

I tried at my site, 2400+2002, with rather long cable BNC-banana, bounce around 150-200pA.

Update:

2400+2002, StdDev = 50.31pA, Avg = 951pA, Min = 818pA, max 1119pA, 500 samples, 50 NPLC
2400+2001, StdDev = 22.11pA, Avg = 1025pA, Min = 969pA, max 1076pA, 500 samples, 10 NPLC

Measurement steps:
2400 set to source zero current, Vcmpl = 12V. Multimeter set to REL to null offset current. SMU set to 0.001uA, measure 500 samples on DMM.

[dr.diesel]

The K2010 lowest current range is 10mA.  Same connection, if I set 1uA it's pretty solid, varies a few counts. 
At 1nA it's just noise.

Ahh, I see. Sorry I did not study the Keithley 2010 datasheet.
Then it is not possible to make this measurement.
Thanks anyways.

Yeah, i'd forgotten myself, or I would have knew better to even try! 

[HighVoltage]

Here are two pictures of a very short term measurement of the 1 nA
Current source: Keithley 2450
DMM: Keysight 34470A

I am traveling right now but when I am back I will post some more long term measurements of the 1 nA source.
The Keysight 34470A seems to be extremely stable and repeatable in this low current range.
 

[Hugoneus]

I spoke with Keithley engineers. It is in fact true that the optimum operating point is 5 NPLC. This provides a balance between 1/f noise and white noise of the analog front-end.

There was nothing wrong with my measurements. It was at the optimal point. I will make capture some data and post it here.

[KedasProbe]

I spoke with Keithley engineers. It is in fact true that the optimum operating point is 5 NPLC. This provides a balance between 1/f noise and white noise of the analog front-end.

There was nothing wrong with my measurements. It was at the optimal point. I will make capture some data and post it here.

Maybe you can provide enough data of your unit to be added in this set of data:
https://www.eevblog.com/forum/testgear/dmm-adc-noise-comparison-testing-project/

[VintageNut]

By the way, from the DMM user manual:

The Model DMM7510 has a nonlinear shape for its speed versus noise characteristics. The Model
DMM7510 is optimized for the 1 PLC to 5 PLC reading rate. At these rates (lowest noise region in
graph), the Model DMM7510 will make corrections for its own internal drift and will still be fast enough
to settle a step response of less than 100 ms.

I don't really understand what this graph means.
Does this mean 100PLC is worse than 1PLC then what is the point of having 100PLC?
I assume not, but what does it mean, that a change from 1PLC to 10PLC will be a lower improvement than what you mathematically expect?

Are 10 x 1PLC better than 1 x 10PLC?

The graph shows the optimum NPLC setting for lowest noise. If you look at the 2182A manual, the same shape graph appears. Chances are the same front end topology is in both instruments.

This NPLC setting is not the panacea for every measurement. It is just information that may be of benefit if you require the lowest noise possible.

I borrowed a 7510 for short while. I installed a factory 4-wire short and let it percolate on DCV auto. The average reading was -3.5 uV and the standard deviation was 200nV. This was many thousands of readings at 10 NPLC.

[ElectroIrradiator]

Have only had time to watch the first half of the video, will complete it ASAP.

Noticed a regular pattern of 'dots' / impressions(?) on the first few shots of the LCD. Wondering what this could be and whether it is noticeable to the naked eye. See for instance clip starting at 09:52. I don't recall seeing anything like that in the reviews of the Keithley 2450 and 2460 SMUs.

If you like, Shahriar, then I would like to donate[1] a long rod of solid 6mm^ø Teflon/PTFE to the cause. You can sharpen it and use it as an alternative pointing tool (at least until people start worrying about buildup of static electricity) instead of that Tungsten tipped marker.

[1] Serious offer, I just need to dig out the bundle I have. Somewhere...

[TiN]

Array of dots on screen are touchscreen spacer dots. They are on all touchscreens, just different size and visible on specific angles.

[splin]

I borrowed a 7510 for short while. I installed a factory 4-wire short and let it percolate on DCV auto. The average reading was -3.5 uV and the standard deviation was 200nV. This was many thousands of readings at 10 NPLC.

200nVrms looks to be way out of spec which is .5ppm Vrms (typical) noise for 1 and 5 NPLC, 100mV range = 50nV rms. I doubt that 10 NPLC would be much different to 5 NPLC.

Its interesting to compare the noise specs with the 34470A which are guaranteed RMS values as far as I can see, so I've taken the 7510 'additional peak noise uncertainty' values and divided by 3.3 to get RMS (apart from the 1 NPLC which is the typical RMS figure).

Assuming I got my numbers right, the Keysight is generally between 10 and 30x noisier than the Keithley. The 7510 datasheet shows that it has a noise 'problem' in the 100V range (in comparison to the other ranges) as pointed out in the review. I'm surprised they didn't resolve it before release, though it still beats the 35570A - at 1 NPLC and below at least. It would be interesting to see actual noise measurements at slower but equal update rates - eg. 1 and 5 NPLC plus averaging for the Keithley versus longer apertures for the Keysight.

All values in Vrms, ppm of range

          DMM7510      34470A            Ratio
100mV
1                .5               6                  12
.2             3.3              35                 10.6
.06           5.2              50                   9.6   
.006        12.7             90                   7.1

1V
1                .09            1.5                16.7   
.2               .48            8.0                16.7
.06             .64          23.0                35.9
.006         5.45          54.0                  9.9

10V
1                .07            1.05              15
.2               .33            5.3                16.1
.06             .64          20.3                31.7
.006         3.33          50.4                15.1

100V
1                 .4             1.005              2.5
.2              2.85           5.03                1.76
.06            5.15         20.03                3.9
.006        30.3           50.04              16.5

1000V
1                 .07           1.0005          14.3
.2                .33           5.003            15.2
.06              .73         20.003            27.4
.006          5.45         50.004              9.2

[ElectroIrradiator]

Array of dots on screen are touchscreen spacer dots. They are on all touchscreens, just different size and visible on specific angles.

Interesting, thanks. I wonder why I have never noticed those before.

[KedasProbe]

This NPLC setting is not the panacea for every measurement. It is just information that may be of benefit if you require the lowest noise possible.

The question is more is it better to use the average of 100 x 1PLC values than use 1 x 100PLC value.
It seems the answer is yes, makes the 100PLC setting more or less pointless.

[Hugoneus]

A few points:

The dots on the screen are not normally visible. They are part of the touch-screen but due to my lighting and camera angle you could see them. I never notice them.

I have not made the NPLC measurements yet, but I will. However, according to the people who designed this instrument my measurements were optimal and earlier criticisms were incorrect.

[blackdog]

Hi,

I have the same problems as Dr. Frank about reading the display of the DMM7510...
I do not care, that the best PLC is about 5...

These jumping around digits have no function anymore, and witch human can read it?
Ofcourse, is see that its usable for industrial test setups, but on my bench no way!

I hope that there is average possible, otherwise this instrument is useless in my eyes...

Keep up the nice video's, thanks for that :-)


Kind regarts,
Blackdog

[splin]

I have not made the NPLC measurements yet, but I will. However, according to the people who designed this instrument my measurements were optimal and earlier criticisms were incorrect.

I have to agree that earlier criticisms were correct, I felt exactly the same when watching it. Most measurements shown were only stable in the first 4 1/2 digits and some, including the 1G resistor were only stable to 2 1/2 digits - hardly a good demonstration of the resolution and stability of a 7 1/2 digit meter. It was almost impossible to follow the changing display on the 1 NPLC measurments. Ideally the averaging function would have been used to increase the resolution and stability of the measurements.

No doubt most of the noise was coming from the sources as the Li-poly battery measurement was stable to 7 1/2 digits. That doesn't explain the very noisy 1G ohm resistor measurement and neither does the datasheet. Looking for the noise specifications on the 10G range, surprisingly it turns out there aren't any specs for the ranges above 10K (that I could find at least). The question then is that an error or is it deliberate? Its not in the reference manual either.

Having said that there was plenty of interesting stuff in the review so thanks for doing it. Incidentally I expect the dropping battery voltage shown was very unlikely to be due to self discharge and much more probably drift due to small temperature changes - battery voltage is very temperature dependant and the changes were only of the order of a few ppm.

[VintageNut]

The current noise floor of a resistor sitting on a table using unshielded cables is something like 1 nA. If you want the maximum digits of a 1G resistor, all of the cabling, connections and the device must be shielded.

If you want the offset of the cable leakage to be subtracted, you have to guard the cables and the device. A guard enclosure inside of a shielded enclosure will eliminate noise and leakage offset.

It is not surprising that a 7 1/2 digit DMM measuring a 1G resistor appears to be noisy. Its probably not the DMM's fault.

[splin]

It is not surprising that a 7 1/2 digit DMM measuring a 1G resistor appears to be noisy. Its probably not the DMM's fault.

Probably not. But getting on for 0.3% noise??? That isn't Johnson noise!

[VintageNut]

It is not surprising that a 7 1/2 digit DMM measuring a 1G resistor appears to be noisy. Its probably not the DMM's fault.

Probably not. But getting on for 0.3% noise??? That isn't Johnson noise!

The 1G ohm range forces 0.68 uA in parallel with 10 megohms. That creates 6.8V across the 1G resistor which causes 6.8 nA to flow through the 1G resistor. (ignoring the solving the exact current)

6.8 nA @ 0.3% is 20.4 pA. 20.4 pA of noise in that resistor subject to the 60 Hz flying outside of the DMM is totally believable.

*edit* 0.69 uA

[Andreas]

Hello,

without having seen the video there is one thing what would interesting to me:
how sensitive is a heated LTFLU1 Reference which is used in the DMM7510 against tilting?

All LM399-based Instruments that I have seen are more or less (depending on individual reference) sensitive if you change the orientation from left to right or over the top of the instrument.

A example for a HP34401A measuring a stable LTZ1000A reference with 7V is attached:
in the diagram. Blue: orientation 0 = normal.
Red individual measurements with 100 NPLC
5 minutes in total with 4 minutes setup time + last minute for averaging final value
Green: Average of the 15 measurement values of the last minute.

01.08.2015 tilting 34401A LTZ1000A #2 100NPLC

0 = norm  = 7.1849649  (flat on the table)
1 = right = 7.1849672  (standing on the right edge)
2 = left  = 7.1849691   (standing on the left edge)
3 = over  = 7.1849698  (top side down)
4 = front = 7.1849819  (standing on the front bumper)
5 = back  = 7.1849568  (standing on the back bumper)
0 = norm2 = 7.1849660
4 = front2= 7.1849802
5 = back2 = 7.1849574
0 = norm3 = 7.1849668

so the largest difference of around 3.5 ppm is between
standing on the front side and standing on the bumpers of the back side.

By the way i have found a Keithley 2000 where between left and right side there were around 28ppm difference.

with best regards

Andreas

[dr.diesel]

New FW for both the 7510 and 2450, 1.6.1a.

Change log is several pages long, but a very noticeable improvement to the touch interface/action.

[HighVoltage]

Thanks for this information.
I will update my 2450 tonight

[HighVoltage]

I just updated my Keithley 2450 to the new FW 1.6.1a

The annoying hesitation when swiping the screen is gone.
This alone is enough reason to update to this latest FW.

In addition I see some small enhancements

[technogeeky]

Can someone replicate the experiment Hugoneus did where you measure and capture the FFT of a large amplitude signal near DC and a small amplitude signal near a few kHz, and see if the spurs are still present in the modern firmware?

I'm curious to see that plot and how good it can look.