Author Topic: USA calibration club  (Read 140228 times)

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Offline Vgkid

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Re: USA calibration club
« Reply #325 on: August 20, 2017, 01:16:20 am »
I have two micro ohm meters (510a,Simpson). It might be a good test.


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Offline bitseeker

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Re: USA calibration club
« Reply #326 on: August 20, 2017, 01:31:28 am »
What kind of resistors are currently in the traveling kit? Anything of interest to micro ohm meter owners?
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Offline CatalinaWOW

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Re: USA calibration club
« Reply #327 on: August 20, 2017, 01:53:38 am »
There were none when it arrived here and I didn't add any.  The only reference parts are the voltage reference and a well calibrated capacitor.
 

Offline bitseeker

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Re: USA calibration club
« Reply #328 on: August 20, 2017, 02:24:29 am »
Ah, OK. I may have been thinking of the capacitor that was added, incorrectly recalling it as a resistor.
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Offline Vgkid

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Re: USA calibration club
« Reply #329 on: August 20, 2017, 11:16:30 pm »
Looking through the specs of most milliohm meters. 1m - 1k will be sufficient for most.
Resistors following the 1.9x decade scheme aren't very common. Especially as you go down in resistance.
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Offline Conrad Hoffman

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Re: USA calibration club
« Reply #330 on: August 20, 2017, 11:55:56 pm »
I was going to put in a 100 ohm resistor, but the weight of the package is right at the limit. I also didn't get the unit aged and measured as well as I'd like. Need a bigger box next time!
 

Offline kj7e

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Re: USA calibration club
« Reply #331 on: August 23, 2017, 01:36:33 am »
Ran 15-30 deg C tempco tests, one with the tempco comp jumper on and one off.  The package will be mailed to bitseeker in the morning.  More charts forthcoming.
 
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Offline bitseeker

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Re: USA calibration club
« Reply #332 on: August 24, 2017, 03:11:11 am »
Thanks, I'll keep my eyes peeled for it.
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Offline cellularmitosisTopic starter

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Re: USA calibration club
« Reply #333 on: August 24, 2017, 06:59:25 am »
Ran 15-30 deg C tempco tests, one with the tempco comp jumper on and one off.  The package will be mailed to bitseeker in the morning.  More charts forthcoming.

Fantastic!
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Offline Vacuuminded

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Re: USA calibration club
« Reply #334 on: August 25, 2017, 08:47:56 pm »
Hi Jason and all involved in this!  Such an excellent idea!  Hi my name is Chris, and I have a problem. <hi chris> :P
Been a long time lurker of eevblog, but at the prompting of someone on the voltnuts mailing list and Jason, finally created an account and am posting here.  Not sure just how much I can contribute to this effort, but if it works out that I can be added to the list I'd certainly like to be involved!  Pretty low on the food chain far as precision measurements go, but slowly getting there.  I presently have a recently calibrated (Simco, fwiw..) 3456A, and am repairing/partially rebuilding a recently acquired 3455A, which may be a perfect platform for experimenting with a more stable reference.  I could only DREAM of the legendary 3458A or similar that so many of you have! 
I am a long time tinkerer of tube type electronics (thus the screen name) and mechanical stuff, very passionate about vintage test equipment and ham radio/communications equipment.  This has awoken my inner OCD and need for extreme accuracy! 
Need to go back through this long thread and re-read everything but this is all extremely impressive and a very interesting idea! 
Regards,
Chris
« Last Edit: August 25, 2017, 08:52:58 pm by Vacuuminded »
 

Offline cellularmitosisTopic starter

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Re: USA calibration club
« Reply #335 on: August 25, 2017, 08:55:59 pm »
Great to have you on-board!  I'll add you to the end of this go-round.

Don't worry about your ability to "contribute" -- we are all helping each other!  Glad to have you participating :)
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Offline bitseeker

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Re: USA calibration club
« Reply #336 on: August 25, 2017, 10:31:14 pm »
Welcome to the club and the active side of the forum, Chris!
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Offline kj7e

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Re: USA calibration club
« Reply #337 on: August 25, 2017, 11:18:48 pm »
Hi Chris, is that some Collins gear in your photo?
 

Offline orin

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Re: USA calibration club
« Reply #338 on: August 26, 2017, 04:53:04 am »
Hi Jason and all involved in this!  Such an excellent idea!  Hi my name is Chris, and I have a problem. <hi chris> :P
Been a long time lurker of eevblog, but at the prompting of someone on the voltnuts mailing list and Jason, finally created an account and am posting here.  Not sure just how much I can contribute to this effort, but if it works out that I can be added to the list I'd certainly like to be involved!  Pretty low on the food chain far as precision measurements go, but slowly getting there.  I presently have a recently calibrated (Simco, fwiw..) 3456A, and am repairing/partially rebuilding a recently acquired 3455A, which may be a perfect platform for experimenting with a more stable reference.  I could only DREAM of the legendary 3458A or similar that so many of you have! 


Hi Chris! ;)

As to that 3455A... how is the jitter in the low digit in hi-res mode with auto-cal on when fed with 10V?  If it's more than +/- 1 digit, then it's probably dielectric absorption in the integrating capacitor.  I've only heard of one without this problem so far.  I've put some Russian teflon capacitors in mine and it's much improved.

Orin.
 

Offline Vgkid

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Re: USA calibration club
« Reply #339 on: August 26, 2017, 05:59:02 am »
Has the package already passed the East Coast yet?
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Offline cellularmitosisTopic starter

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Re: USA calibration club
« Reply #340 on: August 26, 2017, 06:57:34 am »
Has the package already passed the East Coast yet?

Yup, but it'll be running through NJ again to visit nikonoid.  PM me if you want to jump in!
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Offline bitseeker

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Re: USA calibration club
« Reply #341 on: August 30, 2017, 01:52:07 am »
I got a little box today.  :-+ More when I get it up and running.
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Offline Vacuuminded

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Re: USA calibration club
« Reply #342 on: September 02, 2017, 03:54:02 am »
Bitseeker, A WWII hacked up command set transmitter, (not sure who contract built that one), 12V command set dynamotor power supply, and a Hallicrafters "UHF" (really VHF) receiver of the same era.  I have a serious problem when it comes to accumulating boatanchors!  Barely visible behind me is also a B&W 5100B transmitter. 

Orin, I cannot honestly answer the 3455A jitter question, as I discovered the +12V regulator has a fault both producing some very ugly ripple, and loading down the power supply by an extra 200mA.  I located a NOS replacement but it is hanging in limbo at a Houston post office.  No idea when it will arrive.  I'm half tempted to use a TO-220 regulator and just bolt it to the dang chassis, haha! 

Do you know offhand which capacitor(s) you had this issue with?  All electrolytics have now been replaced, but no others have been touched.

Regards,
Chris
« Last Edit: September 02, 2017, 03:56:55 am by Vacuuminded »
 

Offline cellularmitosisTopic starter

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Re: USA calibration club
« Reply #343 on: September 02, 2017, 05:32:11 am »
Gentlemen!

After getting a 16-channel logic analyzer, I have finally made a break-through on my DIY GPIB project!  I can now stream readings from a Keithley 196!

I'll start a thread for this in the project sub-forum, so that I don't derail this thread.  But since I had posted about this earlier in this thread, I thought I'd mention my progress here as well.

https://www.eevblog.com/forum/projects/atmega-gpib-yet-another-diy-gpib-to-usb-project/
« Last Edit: September 02, 2017, 07:54:06 am by cellularmitosis »
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Offline bitseeker

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Re: USA calibration club
« Reply #344 on: September 04, 2017, 06:11:00 pm »
That's great news, cellularmitosis! Thanks for starting a thread on it. I haven't tried logging with my 196 yet and am curious what the deal was with yours. I'll check out the thread.

Back on the calibration front, I was delayed on getting started and then had some GPIB issues with my 34401A. It's all working now. With both the 34401A and 34410A connected to my laptop via 82357B, I'm running a logging test on a 6114A supply warming up at 15VDC. Warm up was approximately 50 minutes to flatten out. It's an all-HP volt party.

The 34410A is marked as having been calibrated on 25 Aug. 2009. The 34401A is unknown. However, they're currently reading within 4 to 5 counts of one another at 15V (i.e., 400-500 µV).
« Last Edit: September 04, 2017, 07:00:15 pm by bitseeker »
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Offline bitseeker

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Re: USA calibration club
« Reply #345 on: September 05, 2017, 12:50:41 am »
I'm on the tail end of a recent heat wave, so it's been a bit toasty in the lab the past few days. Fortunately, today's been a bit better and, from the two-hour period I was logging the reference, stable as far as temperature and humidity.

It's funny that you can see when I was in the lab to start and restart the logging each hour (BenchVue log timeout). I add to the humidity and lower the room's temperature. Who'd a thunk it.

Question: How much of the resolution captured via GPIB is for real on these meters? For example, the raw data had values such as 10.0000512. :o Surely, it can't do 8.5 digits even at 100 PLC. I formatted the stats below to 6.5 digits and added one extra decade for the standard deviation (so it wouldn't be zero).

Here are some stats (second hour only) and graphs from today's logging. I'll upload raw data to the xdev's share.

34401A
Range10VDC
NPLC100
Average10.00028
Std Dev0.000003
Min10.00027
Max10.00029

34410A
Range10VDC
NPLC100
Average10.00005
Std Dev0.000003
Min10.00004
Max10.00006

Attachments
T&H-Hour1&2.png: Temperature and humidity during the two-hour duration. Captured from the TI dongle and logged via EZGPIB.
34401A-Hour1.png: First hour of logging the 10V reference via 34401A.
34401A-Hour2.png: Second hour of logging the 10V reference via 34401A.
34410A-Hour1.png: First hour of logging the 10V reference via 34410A.
34410A-Hour2.png: Second hour of logging the 10V reference via 34410A.
34401A-34410A-10VDC.jpg: DMMs at work.
« Last Edit: September 05, 2017, 12:59:17 am by bitseeker »
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Offline cellularmitosisTopic starter

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Re: USA calibration club
« Reply #346 on: September 05, 2017, 06:21:16 am »
Interesting! 

So, because they show the same std deviation, does that indicate both meters are close in terms of stability and noise, and that the measurement overall was a high quality one?  That would give you good confidence that the 34401A is about 230uV high relative to the 34410A?
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Offline bitseeker

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Re: USA calibration club
« Reply #347 on: September 05, 2017, 06:56:06 am »
I, too, was quite surprised that they both fluctuated by only one count from the average. To minimize noise, I twisted the Pomona leads, disconnected every electronic device in the room except for the participating instruments and my laptop, turned off all the lights, and left the room during logging. I used an integration time of 100 PLC, but still didn't expect the DMMs to be so similar.

I haven't yet dug into the specifics of the data collected during the earlier runs, but if I recall correctly, someone posted that the SVR-T's output is pretty much right on. So, yes, I take that to mean that the 34401A is a bit high.

Hey, it just occurred to me to check the cal message in the menus, since there's no sticker. Bingo! 14 July 2003. Six years older calibration than the 34410A.

Here's some stats from 1 hour of the 34401A logging the output of the 6114A that was powering the SVR-T at 15V.

Average15.0219 V
Std Dev0.00009 V
Max15.0221 V
Min15.0217 V
« Last Edit: September 05, 2017, 07:10:31 am by bitseeker »
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Offline bitseeker

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Re: USA calibration club
« Reply #348 on: September 07, 2017, 04:44:21 am »
There were three programs on the thumb drive to log temp/humidity from the TI module using EZGPIB. One of them always returned -1 due to a conversion problem and only logged to the console. Another one logged to a file. The third one output the correct values and only logged to the console. Two or all three didn't log the date/time, logged as fast as possible (which seemed excessive), and had hard coded values for things such as the COM port, which made configuration more difficult.

I made a new one, TiSensorLogger.488, that logs date, time, and sensor values once per second to both the console and a file. There's a section near the beginning of the source code with configuration variables to set the COM port and location/name for the log file.

The log file that's created has a header row and is tab-delimited for easy loading into Excel, Libre Office Calc, etc. If the file already exists, data is appended to it.

I've added the program to the thumb drive in the package as well as attached here for anyone who has their own module and uses EZGPIB.
« Last Edit: September 09, 2017, 10:18:33 pm by bitseeker »
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Offline cellularmitosisTopic starter

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Re: USA calibration club
« Reply #349 on: September 07, 2017, 04:57:04 am »
Awesome work!  Thanks!   8)
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