USA calibration club

[cellularmitosis]

I intend just to track it personally, out of curiosity.

[jasonbrent]

Seems like I won an auction for 10 VRE3050 voltage references. I want two. The rest are available to club members for what I paid plus shipping.
https://www.ebay.com/itm/132499240091

Let me know.

Randy

Sent you a PM.

[RandallMcRee]

The VRE3050 seems interesting just from a price-point persepective. Look:

https://www.digikey.com/product-detail/en/apex-microtechnology/VRE3050JS/1240-1002-5-ND/2036537

Like, what? they are embedded in some deep pocket military stuff? But I think myself and others just want to know how they compare to an LTZ1000.

I'll ping people when I actually get these in hand. They're being shipped from the UK and I actually don't know what my outlay is in USD. (But its around $5-6 per *not* $90).

[bitseeker]

DigiKey wants $90

Yeah, you did good on that auction. I remember some folks were comparing them to the LTZ1000 and some others, but I don't recall the specifics. There's a thread somewhere around here.

[Andreas]

Seems like I won an auction for 10 VRE3050 voltage references. I want two. The rest are available to club members for what I paid plus shipping.

Hello,

for me it would be only interesting how noisy they are.
I hope you can measure 1/f (0.1 .. 10 Hz) noise.
The 2 pieces (VRE3050AS) that I bought from DigiKey were around 9-10uVpp
which is much against the typical 3uVpp of 5V buried zener devices.

Of course it can be that I picked 2 "mondays devices".
Especially since I bought them shortly after APEX had bought Thaler Corporation.
But my personal opinion is that you get a better price/performance ratio
with AD586LQ (if you pay the DigiKey prices).

with best regards

Andreas

[cellularmitosis]

Andreas, I have recently acquired a low-frequency LNA amp from Pipelie, so I can perform that measurement.

[Andreas]

Hello Jason,

fine.
It would also be interesting how this LNA measures the ADC#21 (arrived AUSTIN today) reference voltage.
here a typical example with my LNA.

with best regards

Andreas

[cellularmitosis]

AHHh it has already arrived!  I won’t be back in town until tuesday      

Something to look forward to

[kj7e]

Jason, these arrived today.







Gotta love quality parts.  Offer is still good if you need one for a one of TiN's 10v references.

[cellularmitosis]

Kj7e, that’s great!  I just mailed my hermetic resistors to Andreas to measure the tempco (I have made measurements but my setup is a bit crude, so it will be good to see how his measurements compare).

When they are shipped back, I will use the ones with the best tempco for TiN’s FX reference.

If you would like to ship your VHD200 to me, I can make some measurements while the rest of the resistors are in Germany.

[cellularmitosis]

Kj7e, actually... since you have a 7.5 digit meter, it would make more sense for me to ship a copy of my temperature control box to you, and then you could measure the tempco.  Have you set up and logging with your meter yet?

[kj7e]

Let me know what the parameters are, start temp, end temp, slope (deg C/Min).  I should be able to duplicate the effort here with what I have on hand.

Yes, I can log the temp and data from the 7510.

[TiN]

My resistors ETA is no earlier than May...

[nikonoid]

This rimes...   another talent


Sent from my iPhone using Tapatalk

[cellularmitosis]

TIN, between kj7e and myself we should have R1 through R5 as hermetic resistors.

Are you waiting on the 7V-10V resistors?

[TiN]

TIN, between kj7e and myself we should have R1 through R5 as hermetic resistors.

Are you waiting on the 7V-10V resistors?

No, those I already have. I ordered LTZ sets for all FX boards and few extras for fun.

[cellularmitosis]

Let me know what the parameters are, start temp, end temp, slope (deg C/Min).  I should be able to duplicate the effort here with what I have on hand.

Yes, I can log the temp and data from the 7510.

Great, I have just gotten back to Austin.  Soon, I’ll make graphs for the measurements I’ve done and make a post in Andreas’ TC thread, which will include parameters for each measurement.

But the gist of it is that I used 10 steps of 1C each, from 25C to 35C, to measure the tempco near 25C.  The best results came from using a 5 minute settling period at each step, and 30 minute plateaus at the top and bottom of each 25-to-35 or 35-to-25 excursion.  Time permitting, I tried to allow three up and down ramps for each resistor, because there was some overall drift of the system, and multiple ramps helps identify that source of error.

I was able to get in some light reading while I was out of town

Edit: feeling a bit wicked with this post     

[hwj-d]

Edit: feeling a bit wicked with this post     

OT:

Yes, stay at home, don't go out, since this number is gone
Can help, if you answe me now ... 

But beware in the mountains too!
Don't you know David Paulides "Missing 411"?
If not, YT to him. 
  

 

[kj7e]

Great, I have just gotten back to Austin.  Soon, I’ll make graphs for the measurements I’ve done and make a post in Andreas’ TC thread, which will include parameters for each measurement.

But the gist of it is that I used 10 steps of 1C each, from 25C to 35C, to measure the tempco near 25C.  The best results came from using a 5 minute settling period at each step, and 30 minute plateaus at the top and bottom of each 25-to-35 or 35-to-25 excursion.  Time permitting, I tried to allow three up and down ramps for each resistor, because there was some overall drift of the system, and multiple ramps helps identify that source of error.

Okay, just fooling around yesterday I ran from 12C to 45C and back down.  Never saw more than a 200mOhm shift on the 13K side and that was only at once over 35C.  For the most part the plot is just a flat line.  I'll post a quick and dirty screen shot of the plots later when I get down to my home office/lab.

[bitseeker]

I was able to get in some light reading while I was out of town

Edit: feeling a bit wicked with this post     

LOL! Nice place for such reading.

[kj7e]

Just a quick TC plot of the 13K side on the VHD200, 5C-45C temp plot;

At 25C, measured -100mOhm (13,000k zero).  On the cold side, the plot peaks just over 25mOhm at 17.5C then is a nearly flat down to 5C.  Above 25C the resistances falls slightly and gets a bit bumpy, I tried this three times and see the same results, not nearly as smooth as I thought it would be.  Dips to -300mOhm at 37.5C then starts to come back up.  So if we take the two most extreme points there is a 400mOhm NTC over 20C or 1.5ppm/C.  Ill test the 1K side next, the main thing is how close the 13:1 ratio remains.

[technogeeky]

Great, I have just gotten back to Austin.
...
I was able to get in some light reading while I was out of town

Edit: feeling a bit wicked with this post     

 

When I first saw the picture, I preferred to think that you were dragging metrology equipment behind you in a sled and making measurements at different altitudes and pressures or something. Something something true dedication to the craft.

[technogeeky]

I actually have a really selfish question regarding the next round of calibration send-arounds. My best multimeter equipment is a pair of Keithley 197s that I have worked somewhat hard to restore to life. One of them is very stable (all the way to ~ 5.5 digits or 220,000 counts), the other is not so stable and isn't even repaired yet. That said, I only need to calibrate one to check the other.

But one of my problems is that these meters use the 1.9 multiplier as the calibration points. So, at least in regard to the kind of calibrations that are possible without a super accurate voltage multiplier, the ranges that I have a chance of calibrating are the 200mV range (with 190.000mV) and the 2V range (with 1.90000V). Given that the reference we are talking about is 10V, I don't see a way to calibrate the higher ranges.

My current plan was to buy a bag of resistors to try and make a divider down from the best average value of the calibrator down to these two voltages, and try to get as close as possible to whatever ratio is required. Unfortunately the best equipment I have for this is also the Keithley 197's resistance ranges, so that seems like putting the cart before the horse.

The other possibility is that I can shoot for some value other than 1.9x that's easier to make with standard resistors (or resistors any of you guys have lying around), since the meter goes to 220,000 counts. I'm not sure I understand the impact this will have on the calibration, but I believe it's possible in principle. Since the procedure is to hook up a source whose voltage you know, and then make the display agree with that voltage you know, there is no reason I couldn't calibrate it at 2.0V. I assume this works in principle too for e.g. the 20V range: I could just try to calibrate it with 10V and make the display read 10V but I think would be a bad idea for a reason I don't understand (if anyone could tell me exactly why this is a bad idea, please do!)

In any case, does anyone have any advice here? Sending them off to be calibrated seems a bit silly, considering the cost of that is several times what I paid for the instruments in the first place. But if I could figure out a way to leverage the reference you're sending around, it would at least be a starting point.

The other reason I'm interested in this in particular on the low ranges, is that I think I once actually calibrated the 1.9V range on the 2nd meter (and hence mis-calibrated, because the meter is still broken). I would love, in particular, to fix that range.

Thanks a bunch!

[kj7e]

If you wanted, I would be willing to check it against my 7510 which was cal'ed in late September.  I calibrated my Keithley 191 with the same 1.9 cal points, just used a decade box and the 7510 to reference the known value to match on the 191.

[cellularmitosis]

technogeeky, I maintain a set of text files which describe the metal foil resistors for sale by the ebay seller "hifi-szjxic":

https://ssl.pepas.com/hifi/

In your case, if you wanted to make an LM399-based transfer standard, you might need to divide 6.95V down to 1.9V, for which you would need a voltage divider of ratio 0.273381.

Using https://ssl.pepas.com/hifi/resistor-ratios-z-all.txt (which just lists his "Z-foil" resistors), several combinations of resistors make ratios which come very close:

Code: [Select]

0.273303167421 [1x RNC90Z 604R00 BR Vishay RNC90 Series Metal Foil Resistors Y1189604R000BR0​L] [1x RNC90Z 2K2100 BR Vishay RNC90 Series Metal Foil Resistors Y11892K21000BR0​L]
0.273303167421 [1x RNC90Z 6K0400 BR Vishay RNC90 Series Metal Foil Resistors Y11896K04000BR0​L] [1x RNC90Z 22K100 BR Vishay RNC90 Series Metal Foil Resistors Y118922K1000BR0​L]
0.273303167421 [1x RNC90Z 6K0400 BR Vishay RNC90 Series Metal Foil Resistors Y11896K04000BR0​L] [1x VTA56Z 22K100 1.0%Z Metal Foil Resistors 0.25w Y009522K1000F0L]
0.273388375526 [1x RNC90Z 150R00 BR Vishay RNC90 Series Metal Foil Resistors Y1189150R000BR0​L] [1x Z201 548R67 0.1% Vishay Z-Foil Series Metal Foil Resistors Y1453548R670B0L]
0.273417721519 [1x RNC90Z 432R00 FR Vishay RNC90 Series Metal Foil Resistors Y1189432R000FR0​L] [1x RNC90Z 1K5800 BR Vishay RNC90 Series Metal Foil Resistors Y11891K58000BR0​L]

Edit: to find those resistors on ebay, just search for the description on ebay.com, e.g. "RNC90Z 432R00 FR Vishay RNC90 Series Metal Foil Resistors".