Agilent 3458A GPIB Data Aquisition software and options ?

[HighVoltage]

Thanks for all your suggestions, I will try different ways, when I have my 3458A at hand.
I will probably not do a resistor change in the beginning, may be down the road....
First I will keep it running to test the stability and drift of the 3458A as it comes.
For that I probably need some high end cables and not my usual pvc or silicone insulated test cables.

[TiN]

You can use single-strand shielded copper UTP cable, like CAT6 Ethernet. It works just fine for DCV stuff.

[Dr. Frank]

..
First I will keep it running to test the stability and drift of the 3458A as it comes.
For that I probably need some high end cables and not my usual pvc or silicone insulated test cables.

What you need much more importantly, is a room with stable temperature. (+/- 2°C over the year, +/- 0.2°C over the measurement run).
Can you use a basement for that purpose?

Frank

[HighVoltage]

Can you use a basement for that purpose?
Frank

No basement where I live, because of high ground water levels.
But I have one room in the lab that has no windows and is pretty stable in temperature changes.

The 3458A arrived and I unpacked it.
It seems the meter was never used. No dust on the fan at all and protective screen was still on the display.

After a few hours of warmup, I hooked up my older GellerLabs 10V Reference (Not the SVRT) and look what is shows:

[TiN]

She's the virgin! Nice score. I bet some folks are seriously jealous now  .
But..... you broke EEVBlog rule - "Don't turn it on, take it apaaaart" 

[HighVoltage]

She's the virgin! Nice score. I bet some folks are seriously jealous now  .
But..... you broke EEVBlog rule - "Don't turn it on, take it apaaaart" 

Actually:
"I took it apart before I turned it on"
Interestingly, you need a Philips PZ2 and two different Torx tools to take the cover off.
I just removed the outer cover and left the analog shield in place.
Absolutely no dust inside.
You are right, it really seems to be a virgin!

[HighVoltage]

Even the fan blades are clean as new.

[ManateeMafia]

It's nice to see one in great shape.  Congratulations.

No basements here in Florida either but you can make do with late night runs when the outside temperature is somewhat stable.

[TiN]

Made in 2011 too, great.

Interestingly, you need a Philips PZ2 and two different Torx tools to take the cover off.

More over, that's actually all you need to fully take everything apart.
Perhaps hires photos of analog section are too much to ask? 
I'd understand if you decide not to take shields off.

Now let it run for a week and get that software and GPIB ready for some long term logging. I'd suggest running SN18 test too, to make sure A3 is good and stable  .

[HighVoltage]

Made in 2011 too, great.

Interestingly, you need a Philips PZ2 and two different Torx tools to take the cover off.

More over, that's actually all you need to fully take everything apart.
Perhaps hires photos of analog section are too much to ask? 
I'd understand if you decide not to take shields off.

Now let it run for a week and get that software and GPIB ready for some long term logging. I'd suggest running SN18 test too, to make sure A3 is good and stable  .

After a while I will remove the analog circuitry shield and take some high res pictures.
Right now I want to make sure it is stable and has no drift.
I read through SN18A, did a ACAL and wrote down my constant values

CAL? 72: 1.00543380
CAL?   2: 7.23733175

Will see, how they are after one week and after a few more ACAL procedures.
It is a surprise, how long the ACAL takes, like 10 min or so.
Compared to the 34470A, which takes only a few seconds.
 

[HighVoltage]

It's nice to see one in great shape.  Congratulations.

No basements here in Florida either but you can make do with late night runs when the outside temperature is somewhat stable.

Thanks,
I think the bigger problem in Florida is the high and constantly changing humidity. As far as I know, many houses in FL have complete air conditioning.
Would be nice to have a lab with temperature and humidity control.

[HighVoltage]

I just noticed, CALNUM? returns "1"
It seems, sometimes we can get lucky.

[ManateeMafia]

Maybe someday there will be a project to build a volt-nut environmental chamber big enough for a 3458A and a few DUT's? I am sure there are many of us that would benefit. Of course, having the room for one would be a bigger challenge.

[HighVoltage]

@HighVoltage: Congratulations !

Q.: How & where did you find a 3458A in such excellent condition ? (just kidding)
Good to see that this adventure has a happy ending ...

 

Thanks, Flinstone it was a good adventure.

It came also with this set of test cable.
It seems like it was hand made or may be it is a production cable of some sort.
The cables feel like teflon insulation, but I am not sure.
Does anyone here know of such a cable?

[joeqsmith]

VERY NICE!!!   Time to put that thing to use.

[TiN]

I know this was covered many times, but perhaps worth to give you few newbie tips on your box
You can run just ACAL DCV, it's about 1.5 minutes, if your measurement will be only DCV. That's enough for SN18 test.

Keep some space at rear of instrument to let it breathe. That fan filter require cleaning every 2-4 month, to keep temperatures good. You can measure internal temp (sensor near front of A1 PCBA) via TEMP? command. Usually it's about 35-38C with ambient ~24-25C.

To get best accuracy, you will want to run ACAL and keep temperatures within 0.3C. Most meters have DCV tempco about 0.2-0.4 ppm/K without ACAL.

If you measure 10K+ohm resistance, make sure you use AZERO ON, OCOMP ON and DELAY 5 to avoid measurement errors. Dr.Frank covered this very well. Keep in mind this setup makes measurements really slow, about 42 seconds per reading.

Backup your CAL data via remote GPIB. Just in case, you know. I had programs for that posted in GPIB article linked before.

Don't apply more than 750VAC, as meter is not rated for that. There is special H01 option for meters which have modifications to accept 1kVAC.

After you get idea what functions you need most, you can program them on numeric keypad as hotkeys. Really saves lot of time messing with clunky UI of 3458A. I have ACAL DCV, TEMP?, MATH NULL, MATH OFF, CAL? 72, CAL? 1,2, TRIG AUTO,TARM AUTO and TRIG SGL on mine.

[Dr. Frank]

HighVoltage,
welcome in the 3458A-Club, finally!

Your unit is from 2012, or younger.
Would you mind sending me the S/N, so a calibration date and 1st owner might be determined?
What did you have to pay for this nice, crisp Instrument?

As TiN already wrote, frequent ACAL is extremely important for this Instrument.
After a 2h warmup, and afterwards one initial ACAL DCV, this drift test (~24h) can be made.

If measuring 4W Ohm with OCOMP ON, DELAY 1 for 10k, DELAY 5 for 100k is necessary / sufficient for max. uncertainty.
Every other range needs 0.1s only.

I'm very interested, what your 3458A delivers for the LTZ, I have measured.

(I'm just sitting in front of mine)

best regards Frank

P.S.: For These DIY cables, please check, that the Isolation is made from highly insulating Plastics, i.e. PTFE, or else. PVC creates big measurment error on 10k and higher.

This can be done with a 10k or 100k resistor, either 2W or 4W mode.
Using 2 or 4 separate cables, which should not touch each other (High cables versus Low cables), this reading should not show a difference to the measurement with the DIY cables.

PVC insulation might creates Errors as high as sevarl ppm for 10k, and several ten ppm for 100k,

[HighVoltage]

OK, the 3458A ran continuously for 1 week now and the drift calculations, based on the SN18A, are 0.11 ppm
This is smaller than the 0.43ppm in the SN18A and seems to be acceptable.
But I have no comparisons.
What is a realistic number to be achieved on a good 3458A?

Then I took some first measurements with a Prologix GPIB to USB adapter and the RF Scientific software by Doktor Pyta
This combinations works well on my Win7Pro Lenovo Laptop

In addition to the 3458A, I hooked up 3 x 34401A in parallel to the same 10V Geller Labs reference.
And here are the results ...
I did not log the temperature over night but would expect a change of about 2 degree drop for the time of the measurements

My big surprise is the difference in the three 34401A meters
The two 34401A meters that behave the same are Agilent branded and may be 6 to 8 years old
The one 34401A that shows the data so differently, is Keysight branded and about 1 1/2 years old

Although the temperature also changed for the 3458A, any measurement changes are tiny, compared to the 34401A meters

Any comments are welcome

 

[Dr. Frank]

OK, the 3458A ran continuously for 1 week now and the drift calculations, based on the SN18A, are 0.11 ppm
This is smaller than the 0.43ppm in the SN18A and seems to be acceptable.
But I have no comparisons.
What is a realistic number to be achieved on a good 3458A?

Then I took some first measurements with a Prologix GPIB to USB adapter and the RF Scientific software by Doktor Pyta
This combinations works well on my Win7Pro Lenovo Laptop

In addition to the 3458A, I hooked up 3 x 34401A in parallel to the same 10V Geller Labs reference.
And here are the results ...
I did not log the temperature over night but would expect a change of about 2 degree drop for the time of the measurements

My big surprise is the difference in the three 34401A meters
The two 34401A meters that behave the same are Agilent branded and may be 6 to 8 years old
The one 34401A that shows the data so differently, is Keysight branded and about 1 1/2 years old

Although the temperature also changed for the 3458A, any measurement changes are tiny, compared to the 34401A meters

Any comments are welcome

Where's the temperature log (at least from TEMP?)??
Over this week, the drift of 0.11pm is without ACAL DCV in between?

All instruments will drift over temperature, they all have typical 0.5..1ppm/°C.

If the temperature is constant to about 0.2°C, you can expect drift/fluctuation of <= 0.2ppm/24hr, compared to an external LTZ1000 reference.

These cited 0.43ppm drift in AN-18 is much too high  a criterion for a "good" U180, as this is only the down-calculated annual drift of 8ppm/yr, to 24h.

So in summary, if you really observed 0.11ppm over one week w/o ACAL in between, and with constant RT, then your 3458A is REALLY FINE.

The 34401A are more sensitive to RT changes, and also show much more fluctuation and noise. They play in a totally different league, one order of magnitude worse than the 3458A.

Frank

[HighVoltage]

Where's the temperature log (at least from TEMP?)??
Over this week, the drift of 0.11pm is without ACAL DCV in between?

All instruments will drift over temperature, they all have typical 0.5..1ppm/°C.

If the temperature is constant to about 0.2°C, you can expect drift/fluctuation of <= 0.2ppm/24hr, compared to an external LTZ1000 reference.

These cited 0.43ppm drift in AN-18 is much too high  a criterion for a "good" U180, as this is only the down-calculated annual drift of 8ppm/yr, to 24h.

So in summary, if you really observed 0.11ppm over one week w/o ACAL in between, and with constant RT, then your 3458A is REALLY FINE.

The 34401A are more sensitive to RT changes, and also show much more fluctuation and noise. They play in a totally different league, one order of magnitude worse than the 3458A.

Frank

Thanks, Dr. Frank

This was just a quick-test to see, if the data aquisition works.
I just moved the instruments back in to my other room and will have temp data as well for the next test

Yes, it was without ACAL in between
Monday 10-10-2016, ACAL and recorded CAL?72
Run for one week
Monday 10-17-2016, ACAL again and recorded CAL?72 again
Difference for 7 days = 0.11 ppm

Yes, I am aware of the huge difference to the 34401A and the larger drift is no surprise.
What surprised me is that one of the 34401A instruments had a totally different drift than the other two.

[Alex Nikitin]

Correct me if I am wrong, however from your graphs it looks like the vertical scale is 0.5ppm/div on the first graph and 5ppm/div on the second. So your drifts are 10 times higher than you've stated - i.e. 1.1ppm for the 3458A + the reference .

Cheers

Alex

[HighVoltage]

Correct me if I am wrong, however from your graphs it looks like the vertical scale is 0.5ppm/div on the first graph and 5ppm/div on the second. So your drifts are 10 times higher than you've stated - i.e. 1.1ppm for the 3458A + the reference .

Cheers

Alex

NO, sorry ...
the 1.1ppm drift has nothing to do with the graph
This is a calculated drift, based on the recommendation in Service Note 18A of the 3458A and the internal comparison of the CAL?72 values within one week of continuous run.

The graphs are showing - on a completely different subject - the measurement differences between 4 meters
And I am not surprised that the two 34401A meters drift down so much down, compared to the 3458A
I am just surprised that one of the 34401A meters has a completely different drift.
 

[Alex Nikitin]

Correct me if I am wrong, however from your graphs it looks like the vertical scale is 0.5ppm/div on the first graph and 5ppm/div on the second. So your drifts are 10 times higher than you've stated - i.e. 1.1ppm for the 3458A + the reference .

Cheers

Alex

NO, sorry ...
the 1.1ppm drift has nothing to do with the graph
This is a calculated drift, based on the recommendation in Service Note 18A of the 3458A and the internal comparison of the CAL?72 values within one week of continuous run.

The graphs are showing - on a completely different subject - the measurement differences between 4 meters
And I am not surprised that the two 34401A meters drift down so much down, compared to the 3458A
I am just surprised that one of the 34401A meters has a completely different drift.

Ah, OK ! The 34401 meters show a surprisingly high drift though, about 10-15ppm /week ...

Cheers

Alex

[TiN]

SN18 over 22 days on mine was -0.03ppm/d.

I monitor CAL constants data all the time though, even during normal datalogs. It takes a second to get CAL? values.
If you want run own checks on my data : everything is here: https://dev.xdevs.com/issues/1285

[Dr. Frank]

Here are my stability measurements. At first, the 10V gain factor over several months, and a 16h stability measurement on a virgin LTZ1000 (Andreas design).

As everybody knows, I switch my 3458A off, when not in use.
Anyhow, the AN-18 short term drift refers very probably to a defective U180, which will drift, even if the instrument is not powered--
Also, my 16h, or longer, stability measurements on LTZ1000 references also show stabilities on the order of < 0.2ppm over their time period.
There's usually no drift in one direction, it's more a random walk / fluctuation visible.



Same goes for the CAL? 72 query, over months, I see no drift over time, nor over temperature (which I would expect), only fluctuations of about +/- 0.2ppm from ACAL to ACAL.



So, obviously, I'm really blessed with an absolutely stable 3458A (U180!), the new LTZ1000 is also pretty stable from the beginning, there are much less spikes, no popcorn noise, and the basement is always at nearly constant room temperature (21.5 +/- 0.5°C). That's volt-nuts' paradise!

Frank