Author Topic: Ultra Precision Reference LTZ1000  (Read 958920 times)

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Offline alex-sh

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Re: Ultra Precision Reference LTZ1000
« Reply #2875 on: February 16, 2020, 08:14:14 pm »
The Vref based on a selected LM399AH inside the DMM6500 may walk (random walk) 5uV p-p at constant temp.
Edit: added "AH"

Afaik the reference inside is SZA263 .

IMHO DMM7510 has got LTFLU (SZA263?).
DMM6500 has got LM399AH voltage reference with Keithley marking - https://xdevs.com/review/dmm6500/
 
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Offline hwj-d

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Re: Ultra Precision Reference LTZ1000
« Reply #2876 on: February 16, 2020, 08:18:18 pm »
Because of the "storm". Maybe the quickly falling air pressure caused the slight upward trend that can be seen at the end of the curve.
 

Offline BU508A

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Re: Ultra Precision Reference LTZ1000
« Reply #2877 on: February 16, 2020, 08:36:09 pm »
The Vref based on a selected LM399AH inside the DMM6500 may walk (random walk) 5uV p-p at constant temp.
Edit: added "AH"

Afaik the reference inside is SZA263 .

IMHO DMM7510 has got LTFLU (SZA263?).
DMM6500 has got LM399AH voltage reference with Keithley marking - https://xdevs.com/review/dmm6500/

The 7510 has the LTFLU-1 inside.


Source:
https://hiveminer.com/Tags/dmm7510,pcb

The SZA263 has been produced by Motorola and is obsolete since a very long time (back in the 1980's I think).
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Offline Edwin G. Pettis

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Re: Ultra Precision Reference LTZ1000
« Reply #2878 on: February 17, 2020, 12:35:00 am »
Yes Motorola originated this part and a whole laundry list of zener based references, some of which live on in various newer reincarnations such as the LTFLU (you might call it the grandchild).  There were several pages of data sheets on various reference zeners and reference amplifiers (aka the SZA263 that eventually morphed into the LTFLU).

Besides the many zener references such as the 1N82xA series, 1N4565-1N4580, 1N3154/A, 1N4775/A, 1N4780/A, series1N935A/B/C, 1N216xA series and 1N941/A-1N945/A series
The precision ref zener series MZ605, MZ610, MZ620 and MZ640
Amplifying regulator diodes, MCA1911 - MCA2234
Low voltage zeners, MZ2360/61

Plus a host of house numbered variations like the SZA263.

Today, the LTFLU is only sourced by Linear Tech and sold only to Fluke, any of these that show up on the flea bays are either from recycled/resold equipment or fakes.  How the LTFLU 'legally' found its way inside a TEK piece of gear is up for speculation, perhaps a quiet agreement between TEK/Fluke/LT but Fluke was the only buyer of these that I had heard of.

Yes I'm aware that ADI took over LT but it is still LT making these parts, ADI doesn't make them.  No I didn't like the take over, I think ADI is messing LT up.
« Last Edit: February 17, 2020, 12:38:00 am by Edwin G. Pettis »
 
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Offline chuckb

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Re: Ultra Precision Reference LTZ1000
« Reply #2879 on: February 17, 2020, 03:25:51 am »
The Danaher Corporation bought Fluke in 1998. Then Fluke was spun off as part of Fortive a few years ago. Danaher also bought Tektronics in 2007 and Keithley in 2010. So Fluke, Keithley and Tektronics were all related for awhile. So at one point they may have shared their best technology like the LTFLU.
 

Offline Edwin G. Pettis

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Re: Ultra Precision Reference LTZ1000
« Reply #2880 on: February 17, 2020, 04:11:47 am »
Interesting, that may have been a viable situation although I'd bet Fluke wasn't too happy about it, never know about these corporate dealings, insanity lives for these <laughing>.
 

Offline MiDi

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Re: Ultra Precision Reference LTZ1000
« Reply #2881 on: February 17, 2020, 10:05:04 am »
Wondering if the LTFLU is orderable as a replacement from Keithley/Tektronix :-/O
 

Offline TiN

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Re: Ultra Precision Reference LTZ1000
« Reply #2882 on: February 18, 2020, 12:38:55 am »
Buying LTFLU without matching resistors is feat with little benefit vs "usual" LTZ.
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Offline Conrad Hoffman

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Re: Ultra Precision Reference LTZ1000
« Reply #2883 on: February 18, 2020, 12:44:40 am »
I was able to improve the thermal performance of my Fluke 731A by tweaking the resistors. The old cardboard box and light bulb trick. It took a few days but was well worth it. That leads me to believe it would work with any of 'em.
 

Offline notfaded1

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Re: Ultra Precision Reference LTZ1000
« Reply #2884 on: February 18, 2020, 01:06:59 am »
Buying LTFLU without matching resistors is feat with little benefit vs "usual" LTZ.

Speaking of this I was wondering... I recently (for the heck of it) picked up an F8842A.  Can I use it to make a decent voltage reference to help with comparing to my new 3458?  I'm already planning on two LTZ1000A's and have the LTZ's but what about using the resistor network from the F8842A with it's reference zener?  I saw someone else did this and boosted the output to make 10V reference.  I was hoping to do something similar.  No one's figured out how to use these resistor networks from an F8842A with an LTZ have they?  Or is that out of the question because they're all matched and you couldn't make it work?  That's the first thing that came to mind... wow a well aged resistor network... with the right ratios could be golden with an old aged LTZ1000A... maybe I'm dreaming?

To add to this... I've kinda come to the conclusion that making or remaking some refs makes more sense than buying old (maybe not working) 732A.  It's a little let down I'd think to pay that much then be stuck trying to take that old foam apart inside and then being afraid of messing up the way it's put together if it doesn't work right.  I can see replacing the batteries and some minor on the edges repairs but tearing into the guts doesn't look like it's for the faint at heart?  I may get one anyhow and try... I'm looking in other places now vs. just Ebay.  I found the 3458 that way.

I'd almost rather sleuth for a 732B I think.  The search for the 3458 was long but maybe it's worth the wait vs. one of your types of teardowns to try and fix an A.

What do you cut out the PCB section with without tearing it up so you have clean cut?  Some kind of dremel or saw of some kind?

Thanks,

Bill
« Last Edit: February 18, 2020, 01:48:31 am by notfaded1 »
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Offline TiN

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Re: Ultra Precision Reference LTZ1000
« Reply #2885 on: February 18, 2020, 03:51:26 am »
Yes and no. With 732A/B/C you get much more than just a reference chip and some resistors. There is far more attention to make everything rugged, battery backed-up and robust enough for everyday use and transport, which is a project on its own, compared to just LTZ module. I've bought 732A some time ago, and it had jumping SZA263 chip. Thread: https://www.eevblog.com/forum/metrology/fluke-732a-with-popcorn-noise-sza/

Since I didn't care about history, I've butchered original SZA chip, replaced it with SZA263 from donor 8842A, and... jumps are gone... yay.... but noise is 20 times worse now... That made me think 8840/8842A's get worse bin of SZA chips. Now I got 5440B reference board, where I can steal two SZA263's and matching PWW resistors to transplant it into 732A to make it useful... But that project sits abandoned since September. I'll revisit it some day.

With LTZ it's easier and cheaper (time wise) to get all parts and get it going. You don't need to dick around resistors and matching, unlike SZA/LTFLU. In worst case if you buy bad 732A, you get nice project box with oven, battery power, low thermal posts where you can put LTZ1000A circuit inside and have fancy looking DIY REF for your lab. ;) One of the benefits that SZA/LTFLU have - you can use same resistors to scale output voltage to 10V directly, instead of additional active components in case of LTZ. Making sub-ppm stable 10V out of 7V is much more difficult task than ultra-stable 7V.
« Last Edit: February 18, 2020, 03:55:03 am by TiN »
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Offline notfaded1

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Re: Ultra Precision Reference LTZ1000
« Reply #2886 on: February 20, 2020, 01:25:06 am »
Making sub-ppm stable 10V out of 7V is much more difficult task than ultra-stable 7V.
Yes and isn't this just what you need to compare with your 3458(s) right?  Maybe not to calibrate with but at least to compare and see how they agree... see what's drifting and which are staying more the same as a group giving some confidence.  I suppose either way measuring both the default 7V stable reference and the boosted 10V would be a good idea anyhow.  Perhaps your unboosted 7V reference is pretty stable but something happened with your boost resistors drifting and now your 10V is off because the boost part of the circuit changed?  I'm thinking this because I'm at the point of ordering PCB's and resistors vs. only looking for 732A/B.  I really like the red FX PCB btw... bummed I missed out on the FX reference.  How did you get so many Fluke-custom hermetic film resistor network P/N 2464707?  Ironically I think the company that makes them is just south of where I work... I think they're in Tempe, AZ.

Bill
« Last Edit: February 20, 2020, 01:49:00 am by notfaded1 »
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Offline Villain

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Re: Ultra Precision Reference LTZ1000
« Reply #2887 on: February 20, 2020, 03:20:44 pm »
Hi,

i have a quick side question. Is it possible to buy a LTZ1000 reference board fully assembled somewhere? Or from someone on the forum? I would pay an appropriate price obviously.

Regards,

Alex
 

Offline Grandchuck

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Offline Villain

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Re: Ultra Precision Reference LTZ1000
« Reply #2889 on: February 20, 2020, 06:14:42 pm »
Oh very interesting, thank you
 

Offline Edwin G. Pettis

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Re: Ultra Precision Reference LTZ1000
« Reply #2890 on: February 20, 2020, 06:26:58 pm »
As expected, the ADI implementation of the LTZ1000 circuits are flawed, they do not conform to the original design and does not produce the original specifications.  I would not recommend buying this board if you really want a good LTZ1000 reference.  They don't know what they're doing yet, they have no experience with this design and should have kept to the original design of LT.  They used the wrong resistors too....I know you were expecting me to say it but it is a fact none the less.
 
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Offline Villain

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Re: Ultra Precision Reference LTZ1000
« Reply #2891 on: February 20, 2020, 06:45:40 pm »
Yeah had a quick look at the design. I must say that i am too lazy to build one myself though, its time consuming..

« Last Edit: February 20, 2020, 06:50:14 pm by Villain »
 

Offline Andreas

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Re: Ultra Precision Reference LTZ1000
« Reply #2892 on: February 20, 2020, 07:40:56 pm »
 

Offline splin

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Re: Ultra Precision Reference LTZ1000
« Reply #2893 on: February 20, 2020, 07:53:37 pm »
 

Offline branadic

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Re: Ultra Precision Reference LTZ1000
« Reply #2894 on: February 20, 2020, 07:54:40 pm »
« Last Edit: February 20, 2020, 07:57:42 pm by branadic »
Metrology Meeting 2020 is canceled. Looking forward for MM2021
 
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Offline Villain

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Re: Ultra Precision Reference LTZ1000
« Reply #2895 on: February 20, 2020, 07:58:10 pm »
I contacted them already, found it an hour or so ago too.
 

Offline Andreas

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Re: Ultra Precision Reference LTZ1000
« Reply #2896 on: February 20, 2020, 08:06:47 pm »
Another possibility:

http://www.friedrich-messtechnik.de/index.php/unsere-produkte/32-uncategorised/71-esn-2010

With best regards

Andreas

Any idea how much it costs?

I only found it by accident when looking for LTZ1000. So I have no idea.

With best regards

Andreas
 

Offline Villain

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Re: Ultra Precision Reference LTZ1000
« Reply #2897 on: February 20, 2020, 08:13:45 pm »
I will let you all know the price when they respond.

edit: IslandLabs guys say 245 eur for LTZ1000ACH board

edit2: the friedrich-messtechnik guy said they only sell to companies
« Last Edit: February 21, 2020, 03:48:12 pm by Villain »
 

Online maginnovision

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Re: Ultra Precision Reference LTZ1000
« Reply #2898 on: February 20, 2020, 08:36:10 pm »
Having bought two from island labs I will say they seem to be good quality. When purchased you get data on aging, noise, current calibration, bom, and schematics. They're also fairly helpful with questions and offer 1 free calibration(I forget the time span).

Attached a couple of pictures I took last year of the LTZ1000A board. If I have time I'll take more detailed ones later of both but since they're in two boxes and one is soldered I don't have time just now.
« Last Edit: February 22, 2020, 05:59:32 pm by maginnovision »
 
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Offline notfaded1

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Re: Ultra Precision Reference LTZ1000
« Reply #2899 on: February 23, 2020, 07:00:47 am »
It just wouldn't be fun not build some of my own... I am interested in converting this into a non-LTZ reference though.  That's why I asked about best way to safely cut PCB's... IDK about tin snips but I know it's been done.  It's in a working 8842A now.  Somehow the reference might be more fun than the old MM to me I think.

Bill
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