Author Topic: LT1021CMH based mini-reference  (Read 33677 times)

0 Members and 1 Guest are viewing this topic.

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #50 on: November 03, 2017, 11:39:22 am »
The 1010B reference is back in my hands and after a 2 hours warm up at 24C in the lab the HP3458A (after ACAL ALL) measures 10.00002V on 10V output. I will log the 1010B over the weekend and post a graph next week, together with the resistance measurements and 1V output value. The residual offset in the measuring system is less than 0.5uV.

The reference will be available again at the end of next week.

Cheers

Alex
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #51 on: November 06, 2017, 04:32:58 pm »
The voltage readings are about -1ppm from what I've measured in August at the same temperature, both for 10V and 1V outputs. I suppose it is stable enough (the popcorn noise is still about 1ppm p-p) .

Cheers

Alex
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #52 on: November 09, 2017, 12:16:35 pm »
The latest measurements at 24C :

10.00002V
1.000041V
10.00044K
1.00010K

The reference is again available.

Cheers

Alex
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #53 on: November 10, 2017, 12:01:06 pm »
Here is the overnight measurement on 10V output with the temperature of the unit measured by a thermocouple. The tempco in this range of temperatures is about +1.25ppm/C .

Cheers

Alex

 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #54 on: March 01, 2018, 03:46:14 pm »
The 1010B is back in my lab after another travel and again available. The measured values are holding inside +/- 5ppm for last six months or so, measured by the same HP3458A Opt 002.

Cheers

Alex
 

Offline TheUnnamedNewbie

  • Super Contributor
  • ***
  • Posts: 1208
  • Country: 00
  • mmwave RFIC/antenna designer
Re: LT1021CMH based mini-reference
« Reply #55 on: March 13, 2018, 09:38:16 am »
The reference just arrived in Belguim! I'll maybe shoot some video of it, unless you prefer me not to.
The best part about magic is when it stops being magic and becomes science instead

"There was no road, but the people walked on it, and the road came to be, and the people followed it, for the road took the path of least resistance"
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #56 on: March 13, 2018, 10:43:36 am »
The reference just arrived in Belguim! I'll maybe shoot some video of it, unless you prefer me not to.

No problem with a video as long as you don't open the reference, it will ruin the calibration.

Cheers

Alex

 

Offline TheUnnamedNewbie

  • Super Contributor
  • ***
  • Posts: 1208
  • Country: 00
  • mmwave RFIC/antenna designer
Re: LT1021CMH based mini-reference
« Reply #57 on: March 13, 2018, 10:48:26 am »
The reference just arrived in Belguim! I'll maybe shoot some video of it, unless you prefer me not to.

No problem with a video as long as you don't open the reference, it will ruin the calibration.

Cheers

Alex



Ofcourse! I was not planning on opening it because of that reason.

Thanks again for making this possible. Seeing my Keithley read 10.00007 has given me a lot more confidence in future measurements. Will start logging tonight.
The best part about magic is when it stops being magic and becomes science instead

"There was no road, but the people walked on it, and the road came to be, and the people followed it, for the road took the path of least resistance"
 
The following users thanked this post: Alex Nikitin

Offline TheUnnamedNewbie

  • Super Contributor
  • ***
  • Posts: 1208
  • Country: 00
  • mmwave RFIC/antenna designer
Re: LT1021CMH based mini-reference
« Reply #58 on: March 24, 2018, 09:57:14 am »
Had a quite busy week so unfortunatly couldn't get as much data as I was hoping to, and haven't been able to make it to the post on Friday. However, I'll send it back on Monday or Tuesday.
Sorry for going over my 2 week slot!

The best part about magic is when it stops being magic and becomes science instead

"There was no road, but the people walked on it, and the road came to be, and the people followed it, for the road took the path of least resistance"
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #59 on: March 24, 2018, 12:22:12 pm »
Had a quite busy week so unfortunatly couldn't get as much data as I was hoping to, and haven't been able to make it to the post on Friday. However, I'll send it back on Monday or Tuesday.
Sorry for going over my 2 week slot!

Not a problem whatsoever, take your time, another week if you need it, there is no queue  at the moment!

Cheers

Alex
 

Offline guenthert

  • Frequent Contributor
  • **
  • Posts: 706
  • Country: de
Re: LT1021CMH based mini-reference
« Reply #60 on: March 31, 2018, 12:09:30 pm »
My HP34401 showed 10.00000V (+1/-2 over N=100, NLPC=10) at about 23°C (can't currently measure temperature with much confidence), which is quite astonishing given that it has not been calibrated in the last two years (if ever).

My Datron Wavetek 1271 showed between 9.999,9752 to 9.999,9766V (min, max each average over 10).  Not sure, whether the variance is due to low frequency noise of the DUT or the one of the internal reference or some draft across the contacts.  My home 'lab' is not suitable for sub-ppm measurements.  This result too is IMHO quite remarkable, given that the instrument was calibrated in 1993 (or at least nobody since bothered to update the calibration time stamp in the NVRAM).

I think this goes to show that with some luck old instruments can be very stable and much more accurate then the nominal specification suggests.
 

Offline ap

  • Frequent Contributor
  • **
  • Posts: 282
  • Country: de
    • ab-precision
Re: LT1021CMH based mini-reference
« Reply #61 on: March 31, 2018, 12:44:36 pm »
I think this goes to show that with some luck old instruments can be very stable and much more accurate then the nominal specification suggests.

There is a reason why many cal labs prefer old, aged precision instruments, such as the 3458A, 732 and 1281 (anyway not available new anymore) over new ones
Metrology and test gear and other stuff: www.ab-precision.com
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #62 on: May 25, 2018, 07:57:18 am »
The 1010B is back in my lab after another travel to Europe and again available.

It looks like my little unit holds the values really well, the difference from the values I've measured a month ago is below what I can measure reliably (HP3458A measures all four values at less than +/-2ppm difference).

Cheers

Alex
 

Offline borghese

  • Regular Contributor
  • *
  • Posts: 70
  • Country: si
Re: LT1021CMH based mini-reference
« Reply #63 on: May 25, 2018, 09:47:58 pm »
I was the last user of the reference, and I used it to calibrate my two HP3456, previous calibration date unknown; surprisingly they were out of tolerance less than 20ppm; excellent and easy to repair instruments.
Alex, maybe you could add the resistance value of 1.111k resistor so to have six digits of resolution; I estimated 1111.210 ohm
Thanks again Alex
Cheers
Cheers
Borghese
 

Offline Alex NikitinTopic starter

  • Super Contributor
  • ***
  • Posts: 1150
  • Country: gb
  • Femtoampnut and Tapehead.
    • A.N.T. Audio
Re: LT1021CMH based mini-reference
« Reply #64 on: August 09, 2018, 09:51:07 am »
The 1010B is back in the lab after a trip to Scotland, re-measured (with essentially the same results) and available again.

Cheers

Alex
 

Offline stijena1973

  • Newbie
  • Posts: 8
  • Country: hr
Re: LT1021CMH based mini-reference
« Reply #65 on: May 31, 2019, 07:56:29 am »
Are there some new data on the mini reference?

Also did You keep track on resistor ratio separately from the reference voltage?

If You did then You probably have some statistical data on the quality of the resistors  internal to the chip...?
 

Offline alex-sh

  • Regular Contributor
  • *
  • Posts: 179
Re: LT1021CMH based mini-reference
« Reply #66 on: February 11, 2023, 12:02:42 pm »
Hi,

Reviving this old post.
Is there any replacement for LT1021CMH?

Thanks
Alex
 

Offline mycroft

  • Regular Contributor
  • *
  • Posts: 70
  • Country: br
Re: LT1021CMH based mini-reference
« Reply #67 on: February 11, 2023, 02:48:44 pm »
Hi!

I am not sure if this LT1021CMH is still in production but Arrow has some LT1021DCH-7 https://www.arrow.com/en/products/lt1021dch-7/analog-devices.
 

Online Andreas

  • Super Contributor
  • ***
  • Posts: 3222
  • Country: de
Re: LT1021CMH based mini-reference
« Reply #68 on: February 11, 2023, 03:23:49 pm »
Mhm,

now more and more hermetically packaged devices run out of production.
(except those SMD packages where the long term stability is still not proven).

LT1021 is one option (perhaps as military version 5962-8860001GA)
AD588JQ would be my choice after the AD587JQ is now near unobtanium.

with best regards

Andreas
 

Offline iMo

  • Super Contributor
  • ***
  • Posts: 4675
  • Country: nr
  • It's important to try new things..
Re: LT1021CMH based mini-reference
« Reply #69 on: February 11, 2023, 06:02:44 pm »
I got LT1027LS8 in past - the smd ceramic one, still "in production", it seems.
It is with 5V output, however.
 

Offline SvanGool

  • Regular Contributor
  • *
  • Posts: 135
  • Country: nl
Re: LT1021CMH based mini-reference
« Reply #70 on: February 11, 2023, 10:10:02 pm »
On eBay the LT1021CMH/883 which I bought there in 2018 is still sold on the same site: https://www.ebay.com/itm/191123710347
« Last Edit: February 11, 2023, 10:12:00 pm by SvanGool »
# Don't hurry, the past will wait. #
 

Offline alex-sh

  • Regular Contributor
  • *
  • Posts: 179
Re: LT1021CMH based mini-reference
« Reply #71 on: February 16, 2023, 07:16:56 pm »
I got LT1027LS8 in past - the smd ceramic one, still "in production", it seems.
It is with 5V output, however.

I saw it, but I am after 10V ref
 

Offline alex-sh

  • Regular Contributor
  • *
  • Posts: 179
Re: LT1021CMH based mini-reference
« Reply #72 on: February 16, 2023, 07:19:22 pm »
On eBay the LT1021CMH/883 which I bought there in 2018 is still sold on the same site: https://www.ebay.com/itm/191123710347

Thank you - will try this one.
Though I was thinking about LT1021B-10 (2ppm/C)
« Last Edit: February 16, 2023, 10:41:59 pm by alex-sh »
 

Offline randymatt444

  • Contributor
  • Posts: 22
  • Country: us
Re: LT1021CMH based mini-reference
« Reply #73 on: April 10, 2023, 06:37:14 pm »
PCB for this design. Comments before I send it out please.

 

Online BD1QMP

  • Contributor
  • Posts: 24
  • Country: cn
Re: LT1021CMH based mini-reference
« Reply #74 on: April 18, 2023, 07:07:43 am »
I have some LT1021BCN8-10, the Temco is negative :(. cannot use 1n4148.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf