Author Topic: 6.5 digit DMM: Keysight 34461A or Rigol DM3068 or... ? (Read 36062 times)

6thimage · « **Reply #50 on:** February 08, 2015, 01:34:18 am »

Quote from: Shim on February 08, 2015, 12:43:18 am

Quote from: LaurentR on February 07, 2015, 11:34:10 pm
Quote from: DJ on February 07, 2015, 07:15:51 pm
Considering the potential for damage with the Siglent continuity check (8V! What were they thinking?) will eventually bite the bullet and get the Agilent. Maybe will wait for the next Rev. Not a need but more of a want.

You'll be disappointed with the 34461A too...
Here is a sampling of what I found around the home:

* Agilent 34461A: 9.4V
* Fluke 87V: 7.3V
* HP 34401A: 6.9V
* Velleman 10ADC ($10 cheapie): 3.0V
* Klein CL1000 clamp (Home Depot grade): 0.4V

There are a few threads about this including: https://www.eevblog.com/forum/testgear/multimeter-with-low-continuity-test-voltage/

Rigol DM3068 (measured with Agilent 34461A) 5.8V

Just measured my Keithley 2000 and it's 6.6V

BloodyCactus · « **Reply #51 on:** February 08, 2015, 03:32:34 am »

interesting. my gw instek 8251a bench dmm puts out 2v for continuity according to my handheld dmm (uei dm393)

Shim · « **Reply #52 on:** February 08, 2015, 04:46:43 am »

The more time I spend playing with these two, the harder it gets to choose between them. I will say that right now, I'm only messing around and not really using them in real world scenarios yet.

I did just have a thought, and tested it to confirm, and thought I should post it up.

For those who think the Rigol has an advantage for continuity due to the fact you can adjust the threshold, I don't think so. With the Agilent, you can use the trending feature and the limits feature and get a much wider range. You don't get a continuous beep, but you can get a beep when the set threshold is past. The trend chart on ohms with limits set is kinda cool too.

blackdog · « **Reply #53 on:** February 08, 2015, 10:09:42 am »

Hi,

I do not understand, talking about the continuous test of the multimeters, I have eight bench multimeters and I use this almost never.
When comparing multimeters, this feature in my eyes completely subservient.
I want a multimeter that temperature is stable, good specifications and good support and it is convenient to use, etc. etc.
Choosing a multimeter as is used in the continuous test of the meter use 4.5 or 9,2V: "it's a little silly"

I have two KEYSIGHT 34461A multimeters and what I think is important is the calibration, how well it is done.
I send my DMM here in Europe, to KEYSIGHT in Germany.
I am sure that it is done properly.

My 2 cents, ;-)

Kind regarts,
Blackdog

KedasProbe · « **Reply #54 on:** February 08, 2015, 10:55:51 am »

You can find my DM3068 remarks here:
https://www.eevblog.com/forum/testgear/rigol-dm3068-issues-remarks-improvements-requests/

nctnico · « **Reply #55 on:** February 08, 2015, 11:00:55 am »

I use continuity testing a lot when repairing and/or reverse engineering circuits or just checking whether there is a connection or short between two points. IMHO a general purpose DMM without instant (fast isn't good enough; it must be instant!) isn't useful for that. Also the voltage used for the continuity test doesn't matter. ICs have zener clamps for ESD protection anyway. What is more important is the maximum current a DMM supplies in continuity test. That should be low enough not to cause damage.

Than again: I'd don't see why someone would buy 6.5 digit DMM just for the continuity test O0

@blackdog: the schematic of your reference looks interesting. Did you use several reference chips in parallel to reduce the noise?

blackdog · « **Reply #56 on:** February 08, 2015, 11:32:38 am »

Hi, nctnico,

I did my best three years ago, in order to keep the noise as low as possible.
I use a stable low noise 8V supply for the LT1021, al lot of filtering and security components, so i wil not blow up the reference.
Now, I would replace the LT1012 opamp by a modern chopper opamp from LT, such as the LTC2057.

The reference is not yet in his cabinet but is located in a polystyrene box, to keep him on as long as possible, until I have a decent housing.
It's a bit of a long-term project, but you have no choice in good voltage references. :-)

Kind regarts,
Blackdog

SteveyG · « **Reply #57 on:** February 08, 2015, 05:12:30 pm »

I'm surprised people are recommending the 34461A over the 34410A. I'd much rather have the better specs over the tacky LCD for a DMM.

blackdog · « **Reply #58 on:** February 08, 2015, 06:44:59 pm »

Hi SteveyG,

Do you have both instruments, that is 34401A and 34461A?
Have you done comparative measurements with both DMMs?

If you look @ the pictures i posted here, you can see higher resulution and i can tell you, the 34461A is more stable.
AC is better then the 34401A.
But, maybe i do not understand your remark?

Kind regarts,
Blackdog

Andreas · « **Reply #59 on:** February 08, 2015, 07:01:25 pm »

Hello,

did you do a ADEV stability calculation over the 2 instruments.
Or do you have the .csv raw data from the comparison measurement?

with best regards

Andreas

blackdog · « **Reply #60 on:** February 08, 2015, 07:08:22 pm »

Hi Andreas,

"Ar you talking to me" (Taxidriver)

Both measurements are done with Keysight BenchVue.

Kind regarts,
Blackdog

SteveyG · « **Reply #61 on:** February 08, 2015, 08:26:31 pm »

Quote from: blackdog on February 08, 2015, 06:44:59 pm

Hi SteveyG,

Do you have both instruments, that is 34401A and 34461A?
Have you done comparative measurements with both DMMs?

If you look @ the pictures i posted here, you can see higher resulution and i can tell you, the 34461A is more stable.
AC is better then the 34401A.
But, maybe i do not understand your remark?

Kind regarts,
Blackdog

I'm talking about the 34410A, not the 34401A. Yes we have the 34410A and 34461A. There is no successor to the 34410A (yet).

wraper · « **Reply #62 on:** February 08, 2015, 09:06:26 pm »

Quote from: Shim on February 07, 2015, 06:18:21 pm

My 34461A came yesterday. At first glance, there are some significant differences between the two. I am actually slightly leaning toward the Rigol.

Is there any comparisons that anyone would like to see while I have both? Got a bit less than 30 days before one has to go back.

Have both, Rigol suck compared to 34461A. Especially on quality and warranty aspect as I said in previous post. Have worse true RMS and larger input leakage current. Not to say Keisight have more bells and whistles. Actually I really regret buying Rigol, 34461A was announced just few weeks after I bought Rigol. On top of that spent half a year to exchange just a few weeks old meter. Just compare how they are built inside to see the difference.

DJ · « **Reply #63 on:** February 09, 2015, 12:38:04 am »

Quote from: nctnico on February 08, 2015, 11:00:55 am

I use continuity testing a lot when repairing and/or reverse engineering circuits or just checking whether there is a connection or short between two points. IMHO a general purpose DMM without instant (fast isn't good enough; it must be instant!) isn't useful for that. Also the voltage used for the continuity test doesn't matter. ICs have zener clamps for ESD protection anyway. What is more important is the maximum current a DMM supplies in continuity test. That should be low enough not to cause damage.

Than again: I'd don't see why someone would buy 6.5 digit DMM just for the continuity test O0

@blackdog: the schematic of your reference looks interesting. Did you use several reference chips in parallel to reduce the noise?

Input protection varies on IC's. Some are zener-clamped, some are body diode-clamped to the rails, some use dielectric isolation with other means of input protection. Leakage through input protection diodes can impact amplifier performance. I rarely use continuity testing on bench meters, usually reserving it for cables and such. I have some older unprotected FET's i would imagine would be smoked by excessive gate voltage, hence my surprise that some of the open circuit voltage of continuity testers on bench meters was that high. On a portable Fluke I could see, but not something I would be using on sensitive circuits. Making a mental note to be double-certain to watch its use.

Andreas · « **Reply #64 on:** February 09, 2015, 05:38:13 am »

Quote from: blackdog on February 08, 2015, 07:08:22 pm

Hi Andreas,

"Ar you talking to me" (Taxidriver)

Both measurements are done with Keysight BenchVue.

Kind regarts,
Blackdog

Yes.

Would it possible to get out the .csv values out of the recordings?
A ADEV stability calculation would be interesting between the 2 devices.
see also the KX thread.
https://www.eevblog.com/forum/projects/project-kx-diy-calibrator-reference-sourcemeter/msg592144/#msg592144

With best regards

Andreas

sotos · « **Reply #65 on:** February 09, 2015, 07:03:20 am »

Ok here are mine also.

Fluke 289 continuity or diode = 5.42v
Agilent U3606A continuity or diode = 4.3v.

blackdog · « **Reply #66 on:** February 09, 2015, 08:13:33 am »

Good morning Andreas, :-)

You can play now...
www.bramcam.nl/Diversen/Andreas-Blackdog-10V-Ref-CVS.zip

Almost 58H data in CVS format of the 34461A and the 34401A DMM's

Kind regarts,
Blackdog

robrenz · « **Reply #67 on:** February 09, 2015, 02:25:22 pm »

@ nctnico Jump on this quick! I guarantee you will not regret this purchase

nctnico · « **Reply #68 on:** February 09, 2015, 02:46:27 pm »

@Robrenz: tempting but if only it was the 8846A with the temperature measurement option.

robrenz · « **Reply #69 on:** February 09, 2015, 03:16:36 pm »

Its no option, its included in the stock meter using a platinum RTD

BUY IT QUICK!

EDIT:

Sorry I misread the 8845 DONT buy that one

Andreas · « **Reply #70 on:** February 10, 2015, 08:54:32 pm »

Hello blackdog,

attached the statistical comparison of the systems:
I think the values are only the offset to the starting value.
(showing the uV deviation over time).

HP34401A:
plotted over time with plotter program shows already discrete voltage jumps.
The standard deviation (8.6 uV) with 200 classes shows that the resolution of the logged data is 1uV.

But all 5uV there is a maximum most probably due to rounding artefacts
from binary internal resolution to the output at the interface.

All in all its no gaussian distribution but 2 overlapping distributions.

Autokorrelation: (don´t know how to interpret but looks strange).

Allan deviation shows 0.8uV stability.
Averaging of multiple values seems not to improve stability.

HP34461A:

On the time diagram the resolution appears much finer and with more stability.
The standard deviation 3.6uV is factor 2 better than above. No discrete values found.
The distribution looks more gaussian. Although 2 distributions available.

Autokorrelation shows a repeated function all 20000 samples.
Perhaps interference (beat frequency) with mains frequency?

Allan deviation also shows 0.8 uV stability.
Getting a little better when averaging 10-20 values.

I cannot finally state what that means. Usually the Allan deviation and standard deviation should be equal for 1 sample.
And also the nearly same value is not clear to me.
But since it is the whole system which is judged including the reference voltage,
the 0.8uV may also be the reference voltage stability which is limiting.

And finally I wanted to know the resolution of the 34461A and got a big surprise when doing standard deviation with 1000 classes:

It seems that the instrument is switching the range or resolution above +10uV difference.
very strange. Does the instrument cheat ? (and secretly switching ranges)
I would have expected better maths in a instrument in this class.

With best regards

Andreas

blackdog · « **Reply #71 on:** February 11, 2015, 03:57:59 pm »

Hi Andreas, :-)

The measurements and outcome are a mix of reference drift, DMM drift, Seebeck effects kabels and tempdrift.

I dit one more measuremt this afthernoon with the 34461A DMM.
Put the range on 10V DC, 100PLC.
And have measured its own drift, input shorted, see the picture.

The drift is about 0.3PPM for 6.5H.
On the Spec. sheet for the 34461A there is for the 10V DC 0.0025 + 4 digit, say 30PPM within Tcal +- 1C
I find my measurements not to bad, if you include all the errors...

Kind regarts,
Blackdog

Andreas · « **Reply #72 on:** February 11, 2015, 10:17:42 pm »

Ok, good zero stability,

but it is only the noise of the ADC + the thermal EMF of the wires which you see there.
The reference voltage stability of the 34461A is not part of the offset measurement.

With best regards

Andreas

Hugoneus · « **Reply #73 on:** February 12, 2015, 03:22:10 am »

What temperature do you guys usually keep your lab at?

blackdog · « **Reply #74 on:** February 12, 2015, 08:35:42 am »

Hi Andreas,

I know, but the noise that you see, is already a fair proportion of the variation of the other measurements, but correct me, if you think it is different.

Hi Shahriar,
The temperature in my LAB depends on my emotional state ...

Normally, the temperature is between 19 and 23C in my LAB.

For my 2x TEK DMM4050 and 2x KEYSIGHT 34461A DMMs I want to make a small box that is temperature controlled.
It wil have a number of Peltier elements to keep the temperature around DMMs fairly stable.
I want to start with the air supply at about 21C, and then measuring with multiple temperature sensors in and outside the multimeters how well the temperature remains stable. This is a project for the coming months.

Again, the schematic that I showed in this topic, is a good reference if you build him well.
The next reference that I'm going to build, contains eight pieces LM399AH, and I will build one, with eight pieces LT1021-5V.
Both reference will be built in an oven, around 42C.
At the moment I test fourteen pieces LT1021-5V, to select out the LT1021 with the largest deviation.

Kind regarts,
Blackdog


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Author Topic: 6.5 digit DMM: Keysight 34461A or Rigol DM3068 or... ? (Read 36062 times)

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