Fluke 8558A/8588A 8.5-digit DMMs

[e61_phil]

This one? Everything except current shunt and digital is on one huge board.

Are there two AD ADUM ICs for galvanic isolation of the analogue board?

Do they use a standard transformer with extra windings for the analogue part or some special DC/DC converters?

[Kleinstein]

Yees. So as I expected, it is based on LTFLU reference. But what's going on with all those LM324's on right side of the board 
Also interesting box between WIMA caps, perhaps LTC1043 based capacitor divider/multiplier? 

A capacitive voltage multiplier (or divider) would absolutely make sense. The Datron 1281 also uses this, though not LTC1043 based.

The lots of LM324 (though hard to read) are really odd, as I see essentially no passives a round them. LM339 would make more sense with the chain of 4095.

[dr.diesel]

it is based on LTFLU reference

Aside from their familiarity of/with the LTFLU, this would not have been a cost issue IMO.  Q&A with their engineers would be sure be fun!     

[srnec]

The SD Card is internal memory for measurements storing.

What is on the sdcard there?

[dr.diesel]

Keysight Germany has commissioned the design of the successor of the 3458A to a German engineering house - three years ago -
their new unit will be launched soon - in term of weeks but no longer ... several sources inside Keysight told me such.

 

[pansku]

Looks like the 3458A follower launch is getting closer. Today I got an application note from Keysight titled "Calculating Uncertainty using Digital Multimeter Ratio Measurement Techniques" and look what was lurking there 

[Mr. Scram]

I guess the successor of the 3458A is the 3458A. I have to say I don't mind the VCR look.

[EEVblog]

They finally changed to the black labeling huh. Worth the upgrade 

[David Hess]

They finally changed to the black labeling huh. Worth the upgrade 

If Darth Vader had a multimeter, that would be it.

[kj7e]

They finally changed to the black labeling huh. Worth the upgrade 

If Darth Vader had a multimeter, that would be it.

I was thinking BatMeter.

[splin]

What chance of a glut of dirt cheap 3458As as cal labs worldwide rush to update to the latest and greatest black-meters? Or at least half so they can't be accused of colour discrimination? 

[maginnovision]

What chance of a glut of dirt cheap 3458As as cal labs worldwide rush to update to the latest and greatest black-meters? Or at least half so they can't be accused of colour discrimination? 

I'm guessing 0.

[splin]

What chance of a glut of dirt cheap 3458As as cal labs worldwide rush to update to the latest and greatest black-meters? Or at least half so they can't be accused of colour discrimination? 

I'm guessing 0.

Ahh, you're no fun; cold hard reality is an unwelcome intrusion into a pleasant, if futile, daydream... 

[TiN]

Yup, zero. Nobody sane would replace meter with a history for a new untested black box.
Enough to say, Fluke managed to get key transfer specifications worse on every generation (Datron 1281 -> 8508 -> 8588A)

[splin]

Yup, zero. Nobody sane would replace meter with a history for a new untested black box.
Enough to say, Fluke managed to get key transfer specifications worse on every generation (Datron 1281 -> 8508 -> 8588A)

Worse?  Or more realistic perhaps? Maybe they are simply being more conservative with their specifications?

[TiN]

Well these are specifications from manufacturer. Datron 1281 had no known problems to meet it's specification, so calling it's amazing performance unrealistic is a long shot.  We can all hope and expect that meters perform better than specifications, but it is hard to put just hopes into the calibration report. I'd love to be proven wrong if somebody actually have calibrated standards (732B/742A/SR104 etc) and 8588A to collect the data, can supply with Python scripts to do so. I have access only to 1281s, 3458s and 8508.

[Kleinstein]

Checking if a meter meets the transfer specs does not need calibrated standards. It is about short time stability and linearity.  Anyway a check on a few meters does no say much on how conservative the specs are. These specs need tests on many meters and probably some estimates that can be more or less conservative. There even is a chance they may have to (or can) be revised when more units are in service an tested.

[e61_phil]

I was searching for Datron 1281 transfer specs, but could only find stability specs.
Has anyone a link for a document with transfer specs?

[maxwell3e10]

From the manual https://www.elso.sk/media/download/pdf/fluke/man/Datron-1281-user-manual.pdf
the transfer accuracy for DCV is 0.2 + 0.05 ppm on all ranges.
In contrast, both HP3458 and Fluke 8588 have 0.05 + 0.05 ppm transfer accuracy on DC 10 V range. But for some of the other ranges it is indeed worse than 1281.

[e61_phil]

From the manual https://www.elso.sk/media/download/pdf/fluke/man/Datron-1281-user-manual.pdf
the transfer accuracy for DCV is 0.2 + 0.05 ppm on all ranges.

Do you have a page number for me? I searched the document for "transfer" but couldn't find that.

I'm especially interested in the 10k Ohm transfer, but voltage would be a good starting point.

[maxwell3e10]

Its called TEN MINUTE STABILITY SPECIFICATIONS. 10 kOhm is 0.2 + 0.1 ppm for 1281, while for Fluke 8588 it is 0.2 + 0.5 ppm, so indeed significantly worse.

[e61_phil]

Its called TEN MINUTE STABILITY SPECIFICATIONS. 10 kOhm is 0.2 + 0.1 ppm for 1281, while for Fluke 8588 it is 0.2 + 0.5 ppm, so indeed significantly worse.

stability isn't transfer!

stability describes noise only, while transfer includes other errors. And you're comparing 95% specs against 99% specs

[The Soulman]

Its called TEN MINUTE STABILITY SPECIFICATIONS. 10 kOhm is 0.2 + 0.1 ppm for 1281, while for Fluke 8588 it is 0.2 + 0.5 ppm, so indeed significantly worse.

stability isn't transfer!

stability describes noise only, while transfer includes other errors. And you're comparing 95% specs against 99% specs

Is it?
What other errors will be included in the transfer specification?

[e61_phil]

Its called TEN MINUTE STABILITY SPECIFICATIONS. 10 kOhm is 0.2 + 0.1 ppm for 1281, while for Fluke 8588 it is 0.2 + 0.5 ppm, so indeed significantly worse.

stability isn't transfer!

stability describes noise only, while transfer includes other errors. And you're comparing 95% specs against 99% specs

Is it?
What other errors will be included in the transfer specification?

Linearity for example (not only of the ADC, also current source)

[The Soulman]

Its called TEN MINUTE STABILITY SPECIFICATIONS. 10 kOhm is 0.2 + 0.1 ppm for 1281, while for Fluke 8588 it is 0.2 + 0.5 ppm, so indeed significantly worse.

stability isn't transfer!

stability describes noise only, while transfer includes other errors. And you're comparing 95% specs against 99% specs

Is it?
What other errors will be included in the transfer specification?

Linearity for example (not only of the ADC, also current source)

Good point, that doesn't really matter when comparing two resistors of the approximately same value, but
obviously does when comparing a 1K to a 10K resistor for example.
I would assume the "general" linearity specifications apply, I would also assume the linearity doesn't change significantly over time,
so short term specs wouldn't be much better if they were given.