FLUKE 8508A Reference Multimeter and other 8.5 digit DMMs

[quarks]

because this belongs into Metrology, I start this topic based my old 8.5 digit DMM post

https://www.eevblog.com/forum/testgear/8-5-digit-dmm/msg258880/#msg2to58880

I will update all my relevant data and post it here

[quarks]

Here is a collection with more details about the kings of the DMMs:

Advantest R6581 / ADCMT 6581
http://translate.google.de/translate?hl=de&sl=ja&tl=en&u=http%3A%2F%2Fwww.adcmt.com%2Ftechinfo%2Fproduct%2Fend_of_sale%2FR6581D%2Fco_R6581D.html&sandbox=1
http://www.adc-tech.co.jp/techinfo/product/end_of_sale/R6581D/c_R6581D.html
http://www.123485.com/et/hi/148_5.html

Datron/Wavetek 1271 and 1281
http://www.fluke.com/fluke/uses/Multimetros-Digitales/Fluke-1281.htm?PID=56003
http://datronconnection.com/749/Datron_1281.php
https://www.amplifier.cd/Test_Equipment/other/Datron_1281_Multimeter.htm
https://xdevs.com/fix/d1281/

Fluke 8508A (Option 01 for rear input Ratio meassurement)
http://us.flukecal.com/products/standard-laboratory-meters/8508a-reference-multimeter

HP/Agilent/Keysight 3458A (Option 02 or HFL for best DC accurracy)
https://www.keysight.com/en/pdx-2905513-pn-3458A/digital-multimeter-8-digit

Keithley 2002
https://www.tek.com/tektronix-and-keithley-digital-multimeter/keithley-2002-series-8%C2%BD-digit-multimeter-scanning

PREMA 6048
https://www.prema.com/index.php/de/service/messgeraetewartung/item/download/194_de6b95d4c0cc26e9c9882c7df7cf7748
http://w.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Prema/Prema_6047_6048_DMM_Operator_Manual.rar
http://translate.google.de/translate?hl=de&sl=auto&tl=en&u=http%3A%2F%2Fohh.de%2F6048.htm&sandbox=1

Solartron 7081
http://www.perdrix.co.uk/Solartron7081/index.htm
Our member Mickle T. had some great posts on modifying a 7081 on bbs.38hot.net but they seem to be deleted
but here is his great work saved
http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/Solartron/Solartron_7081

Transmille 8000 Series (8080, 8081 and 8881)
http://www.transmille.com/8000-series

Transmille 8104 (newest product in the list)
http://www.transmille.com/8100-precision-multimeter

ZIP Nauchpribor KM300
http://translate.google.de/translate?hl=de&sl=ru&tl=en&u=http%3A%2F%2Fwww.znp.ru%2Fprod%2Fkm300.htm&sandbox=1

[quarks]

placeholder for comparison data

[e61_phil]

Thanks, quarks.

I made a few photos of the 8508A and the 3458A as mentioned in the other thread.

The room temperaruee here is almost exactly 23°C. The 8508A_complete shows the 8508A sitting on a desk and running since a couple of weeks. I can't find a big thermal gradient from front to back. The power supply sections seems to be a bit hotter than the rest.

The other pictures show the temperature of the input jacks. After the stories I heard from the PTB guy I expected a much bigger difference between the inputs of the 3458A. It seems to be in the range of 1K.

[dl1640]

The 3458 input LO is hotter than input HI in your picture. Do you have running instrument stacked under 3458?
1K difference is impressive.

[e61_phil]

The 3458A sits on top of another 3458A. I will make more pictures later.

I played with the color grading and the heat doesn't seem to come from the instrument below.

Perhaps Tin can tell us how it looks behind the binding posts

[TiN]

Maybe I'm not as well respected as "PTB guy", but what is here don't quite agree. 

Actually went thru effort to make images. So off we goes:



Overall setup. Poor 3458A jammed under Hulk, flukey on top. No other running gear around. Far from optimal. I would never set instruments like this for any meaningful transfers/calibrations, but they sit now, since I just need to test code and still do minor fixes for Hulk.

First impression? Thing on top like to cook... Not as hot as K2001/K2002, but far closer than 3458A ever be with dirty filter...
I don't like heat from large bad contrast LCD leaking into sense posts. 3458A is nice in that respect, as noisy out-guard display is as far as possible from input terminals.



Top to rear gradient. +52C near rear PSU, +45c at rear posts. +38ish at front posts. Maybe now we see WHY 8508 needs 4wV mode, while 3458A works just fine with 2-wire?



Fluke terminals close-up. Left = Rear block, right = front block. Here you can very well see why putting single marker in center of the post is POINTLESS  . Over 5°C gradient from post base to end. 



Keysight 3458A terminals close-up. Front only Clearly visible effect of connected cable, acting as a heatsink. You say no fair comparison with cables attached? Well, who gives a byte of binding posts temperatures without any signal attached to unit?

Here are 5720A Hulk terminals and face overall pic again.



Now something different, to make sure this thermal camera does not tell us lies, in terms of relative gradient 



This is my secondary 10V FX reference box, in modified Fluke 792A power pack chassis. Good luck finding any thermal gradient anywhere.



Comparison between 3458A (other unit) and 6581T (just for giggles). Not that uniform temperature help Advantest in anything, it is still lightyears away from proper 8.5-digit meters. 

And overall setup 2, sitting in unconditioned room at +29c ambient. 



I think we will see who is what when I progress to tempco testing on both 3458A/3458X and 8508A. 

quarks

Thanks for reviving thread. I only wish you would add also K2002+1801 preamp head spec into your nice charts. That is best AC-powered nanovolt setup money can buy, short of cryogenic stuff. 

[quarks]

quarks

Thanks for reviving thread. I only wish you would add also K2002+1801 preamp head spec into your nice charts. That is best AC-powered nanovolt setup money can buy, short of cryogenic stuff. 

if you can give me the specs I can add it

BTW: What do you guys use to get so many temperature points in your thermal images?

[e61_phil]

Maybe I'm not as well respected as "PTB guy"

Yes, and the point isn't the PTB, the point are your prejudices. It is more than clear, that you don't like the 8508A for whatever reason. I don't want to say you're wrong with anything you said here. But with such an attitude it isn't even possible to make objective comparisions. Even if you don't do it intentional. Please try to be a little bit more objective. It would be a pitty if you find something out and it isn't really trustworthy (at least to me) because of your attitude to the 8508A. The 3458A seems to you like a car for many germans

[quarks]

one thing I like very much about Fluke 8508A is the very fast warmup time
att. are some of my DMMs in comparison



my guess is, it has to do with fanless design of 8508A and 1271/1281 vs. 3458A and R6581 with fan.

[TiN]

e61_Phil, perhaps my semi-serious jokes are missed in language differentials . I'm in the camp "moar meters, different and shiny". I'm sure that all cared 3458A and 8508A are meeting and exceeding their specifications, and are good for what they designed for. 

What I was trying to highlight, is the fact that one should get the tools (like meter) for the job, and verify it if meets the requirements in your specific conditions and application. And list of conditions to verify is very long in case of any ppm-level uncertainty measurement. Saying meter A is better than meter B because there is 1K temperature difference at center of the unconnected post close to statement that Caterpillar is better car than BMW.

I intend to continue comparisons (thanks to chance and ability to do so, equipment like this not easy to find), and the more ideas for them the better. I wouldn't take thermal images without you, so thank you for that. Maybe I will change my mind few months from now, but now I'm obviously biased here, because I own and know my 3458A's and 2002’s already. But if you ask me to compare 100Meg range of 3458 to HiOhm one of 8508A I'd say it is barely useful due to big difference in voltage/current, and 3458A is not a tool for that without additional high-voltage source.

You present your data and result, I present what I get here, community wins. What we like or not - that is all subjectives and irrelevant in metrology.

Quarks, spec can be found here for amplified 2001/2002:
https://xdevs.com/doc/Keithley/1801/1801%20Nanovolt%20Preamp.pdf
I used Fluke SmartView app, that eats IS2 files from Fluke imagers and allow you to analyze and post-process data on confuser. Easy to use and unusually free.

[quarks]

Quarks, spec can be found here for amplified 2001/2002:
https://xdevs.com/doc/Keithley/1801/1801%20Nanovolt%20Preamp.pdf

@TiN,
here you go

Keithley 2002 + 1801 Preamp (20 µV to 2 mV DCV range)


Keithley 2002 + 1801 Preamp (500 µV ACV range)


Keithley 2002 + 1801 Preamp (2 mOhm to 200 Ohm range)

[branadic]

Thermal images are nice and colorful, but have you considered the different transmission coefficients of the different materials and their reflection coefficients as well or did you manage to coat everything with a coating of known transmission coefficient? I guess no, thus all the pictures are what they are, nice and colorful, but I won't give a damn on a single temperature difference, even absolute nor relative to each other.

-branadic-

[e61_phil]

e61_Phil, perhaps my semi-serious jokes are missed in language differentials .

Yes, seems to be a missunderstanding from my site. I have to apologize!


In terms of branadics thoughts: Does anyone tried normal temperature sensors in/on the binding posts?

[Andreas]

Regarding the temperature of the binding posts:

I never understood why the + and - poles of (most) high precision instruments are stacked (different internal temperature) and not side by side (more equal height/temperature).

with best regards

Andreas

[fonograph]

I would like Keithley 2002 and Transmille warm up times/curves please.

[TiN]

I'll do 2002 sooner than later (rare chance, as it's first time this year both of them are turned off for longer than 5 minutes). 

[montemcguire]

Thermal images are nice and colorful, but have you considered the different transmission coefficients of the different materials and their reflection coefficients as well or did you manage to coat everything with a coating of known transmission coefficient? I guess no, thus all the pictures are what they are, nice and colorful, but I won't give a damn on a single temperature difference, even absolute nor relative to each other.

I'm probably wrong, but a reflective coefficient only matters when the thermal images are taken in an environment with other IR radiators. Essentially, if you take these pictures in the dark, won't everything in the thermal image just be 'black body' and no IR reflection? Not sure how to arrange for no external IR sources, but assuming that this is possible, can't a thermal image actually work in a perhaps special case?

[Henrik_V]

If I remember rigth, the 'PTB guy' (retired now) used two 4mm PT100 sensors to look for binding  post temperature differences, and as I know him, I wouldn't be suprised if calibrated both sensors in a gallium cell and water tripple point shortly before ...
Temperature measurements should be done with the actual used connetion cables, since they transport heat .... (my point of view).

BTW the same guy always stacked 'his' calibrators, DMM with at least 4 cm free space inbetween.  We missed the standoffs at our calibration service at the Maker Faire and used LEGO from another stand to build some standoffs

[try]

I miss the PTB guy with his excellent teaching abilities. 

This is how he set up the booth at the maker fair:
https://www.mikrocontroller.net/attachment/257274/DC-Messplatz_klein.jpg

Application of PTB-approved kindergarten equipment by his successors:

https://www.mikrocontroller.net/attachment/341766/Lego_is...universal.jpg

https://www.mikrocontroller.net/attachment/341783/Kommentierter_Messplatz.jpg

Best regards
try

[TiN]

Yea, I'm used to lift meters and give them breathing space when doing best effort cals too.
That's why having fan on 3458A is better in my setups, keeping unit cool so no need to worry as much about putting other stuff on top/under them.
With K2002 always have to worry about vent exhaust (on left side).

[dl1640]

I miss the PTB guy with his excellent teaching abilities. 

This is how he setup up the booth at the maker fair:
https://www.mikrocontroller.net/attachment/257274/DC-Messplatz_klein.jpg

Application of PTB-approved kindergarten equipment by his successors:

https://www.mikrocontroller.net/attachment/341766/Lego_is...universal.jpg

https://www.mikrocontroller.net/attachment/341783/Kommentierter_Messplatz.jpg

Best regards
try

Nice *banana* plugs, recently i acquired some such plugs, but they dont fit my 3457 3458 well

[try]

What exactly is the problem with the hollow plugs?

[dl1640]

They cant plug into the binding posts, seems the diameter is not accurate, larger than 4mm?, maybe they need to be shrink a little bit.

[Dr. Frank]

These hollow plugs in the pictures are from mc, multi contact, Swiss; acquired by Stäubli group.
I use them in electronics and metrology for over 30 years, also w/o problems in all hp DMMs, and the oldest ones are still working very well, because they do not oxidize, like most of the other crap.

These are really high quality, long endurance, gold plated, low e.m.f., and fit very well, normally, because they are made from phosphorous bronze.

You might have problems only in segmented jacks, e.g. on handheld DMMs, current input jacks, with plug detection.

As these are expensive, non fitting ones could be fakes.

Frank

PS: The plugs LS4 is still available at about 80 Cents /EA. The assembly with  plastic case KT4B is called SLS4-B,