Electronics > Metrology

Ultra Precision Reference LTZ1000

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quarks:
While waiting for the ESI gear I ordered for my resistance measuring stuff, I started to look for the best possible voltage reference.
I already have a few good DC Sources (Valhalla 2701C, Burster 6406, Knick SJ300 and a few Geller SVRs), but I do not have a "real" Voltage Reference Standard (like Fluke 732B or a Datron or any similar) to compare them to.

Besides "Josephson-Voltage-Standard" the next best still seems to be LTZ1000 and this is the reference I would like to give a try.

I read a lot of datasheets, Application Notes, Nuts&Volts posts, Bop Pease stuff, Joe Gellers info's (incl. his Patent), discussions in different blogs and many more sources.

Here are a few links I found good and worth reading (and translating):

http://www.linear.com/product/LTZ1000
http://www.maxmcarter.com/vref/
http://www.febo.com/pipermail/time-nuts/2008-November/034723.html
http://www.hellocq.net/forum/read.php?tid=139719
http://www.amobbs.com/thread-3593996-1-1.html
http://www.eefocus.com/lymexbg2vo/blog/09-12/181353_9b971.html

The last one shows a lot of boards, so I think of trying to get one or more, if that is possible.

Now I would be interested if anyone here in the forum has already done a LTZ1000 DIY project and is willing to share the outcome?
Or maybe one of you know where to get a well designed board or plans to do one and can offer to buy it?

thx
quarks

EEVblog:
The LTZ1000 is the 7V reference used in industry standard HP3458A 8.5 digit multimeter.
Part number 03458-66509
No oven, it just sits inside the meter case on it's own board with it's circuitry.
If it's good enough for the worlds best reference multimeter used in practically every cal lab, then it's good enough for any DIY project!

Dave.

(In)Sanity:

--- Quote from: EEVblog on January 13, 2013, 07:29:22 am ---The LTZ1000 is the 7V reference used in industry standard HP3458A 8.5 digit multimeter.
Part number 03458-66509
No oven, it just sits inside the meter case on it's own board with it's circuitry.
If it's good enough for the worlds best reference multimeter used in practically every cal lab, then it's good enough for any DIY project!

Dave.

--- End quote ---

This is a very interesting piece of information.  I had no idea the LTZ1000 reference was used in the 3458A.   I have a very nice condition 3457A which I believe uses the LM399 as a reference.   I have to wonder if their is any advantage to upgrading the 3457A to use an LTZ1000 or is it's 6 1/2 (7 1/2) digit resolution would see no real advantage?  It would of course need to be re-calibrated which I'm due for anyway.  I'm always looking to improve something just for the sake of doing so.   

On another note an interesting video might be one on temperature coefficients and techniques used to stabilize and/or compensate for temperature drift.   

Jeff

PA4TIM:
Dave, it depends on how you look at it, like the LM399 the LTZ1000 has a heater resistor so it is inside his own little oven.

A member of the voltnuts list has just modded his solartron 7081 and replaced the zeners with a LTZ1000 board. He also did measurements on noise and stability. He is really good on this stuff. 

Voltnuts is a "sister" of timenuts. Several members made LTZ1000 references. Jim Williams has an appnote about a sub-ppm standard and he used a LTZ1000 too. I made his design but then using a LM399 because I have no source for a LTZ1000.

I have a Fluke 332, a guildline 4 Standardcell cabinet ( will all calibration reports since production) and several other Fluke, Philips and homebuild calibrators/references. (a gift from a company that closed down theirs calibration lab) Besides that ESI resistors, two Flukes and a ESI KV devider, standard capacitors and inductors ect. And the famous, still made GR-1620 capacitance bridge that was first used by the GenRad lab self, then when it closed moved together with a staff member to a national brittisch Cal-lab and later sold to a dutch call lab and finaly ended in my lab.

Network analyses, capacitors anf voltnutting is my thing. Nice to meet an other voltnut. Blackdog, here on the forum also has a lot of knowledge about voltreferences. If i remember well also with the LTZ1000 but i think we will see him here. LTZ1000 works like a magnet too voltnuts .

I'm very interested to see your design and the result. I read the hardest part is something with setting the heater current. But some say that is not, others say it is. As far as I found out it only was a problem on some old 3458 reference boards

The things that make it hard are the parts around it. My 10V LM399 bases reference is now powered on 24/7 for months. I monitored it for months and it becomes more stable every month but still it varies 2-4 ppm and that is a reaction on temperature and humidity. So one of my next projects Will be an oven for the reference and a relative humidity and temp meter that will serve to give me those values and work as a controller for the oven. ( as soon as i find out if it is nessaserry and possible to keep humidity in the oven constant) for temp I will use one of Williams early designs when he was stil working for MIT.

(In)Sanity:

--- Quote from: PA4TIM on January 13, 2013, 08:15:04 am ---The things that make it hard are the parts around it. My 10V LM399 bases reference is now powered on 24/7 for months. I monitored it for months and it becomes more stable every month but still it varies 2-4 ppm and that is a reaction on temperature and humidity. So one of my next projects Will be an oven for the reference and a relative humidity and temp meter that will serve to give me those values and work as a controller for the oven. ( as soon as i find out if it is nessaserry and possible to keep humidity in the oven constant) for temp I will use one of Williams early designs when he was stil working for MIT.

--- End quote ---

So does this mean that my 1993 3457A should be far more stable then a fresh off the shelf LM399,  or do they degrade over time?   I fear becoming a volt nut,  I already fuss about stuff being out of tolerance by 10 uV,  let alone a fraction of that. 

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