Author Topic: Ultra Precision Reference LTZ1000  (Read 976924 times)

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Offline acbern

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Re: Ultra Precision Reference LTZ1000
« Reply #800 on: February 06, 2015, 03:05:12 pm »
Still off topic (LTZ1000) here:
In principle it applies to all imports to the EU. And within the EU, you can freely ship it (unless it is a controlled item such as military electronics or so, we normally dont own these).
I would think that the specific case was an exception, I had to deal with many guys from customs over many years, at the local customs office and through freight companies like fedex, and I only buy used stuff, never been a problem.
 

Offline quarks

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Re: Ultra Precision Reference LTZ1000
« Reply #801 on: February 06, 2015, 03:22:05 pm »
I read this with great interest, as I am importing a lot of test gear from the US for my personal use, and never had an issue in the customs office, and so this sounded scary initially. So I looked up the ProdSG in German, and it seems to me it is sufficient to certify, it is for repair and/or refurbishment.

Excempt from CE marking is:
"gebrauchte Produkte, die vor ihrer Verwendung instand gesetzt oder wiederaufgearbeitet werden müssen, sofern der Wirtschaftsakteur denjenigen, an den sie abgegeben werden, darüber ausreichend unterrichtet"

As you have translated, but I just did not get it in the english wording. Sorry for the German, but I tinks those who are potentially affected understand it, so helps. It does not even require repair, "aufgearbeitet" (to refurbish) is a wide field, it may also mean calibrate and adjust or whatever. So I would not accept this abitray judgement of the local guy, bring this up to the local head of the department, this was not lawfull.
In German, sorry: es handelt sich um einen Zoll-Verwaltungsakt, gegen den man zumindest Einspruch einlegen kann. Ggf. auch klagen, (wenn man viel Zeit hat. Der Einspruch geht schneller, und den entscheiden meistens Leute die mehr Ahnung haben und dann sollte es das normalerweise gewesen sein).

As stated, I even had a personal discussion about that with no luck and just gave up.

In your own case, if your custom official in charge does not look/care, then you are just lucky.
But if they care, they will/can send the gear in question to an official place to have it checked for CE conformity and you will have to pay for shipping and the test if you want to have the gear in your hands. If you do not agree, you can of course try to fight against this "Zoll-Verwaltungsakt" but that is not worth it (at least for me).
« Last Edit: February 06, 2015, 03:32:25 pm by quarks »
 

Offline quarks

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Re: Ultra Precision Reference LTZ1000
« Reply #802 on: February 06, 2015, 03:29:41 pm »
What about equipment imported from another EU country?

Very stupid but within the EU you can buy gear without CE Mark with no problems, probably because this is not handeled as an import. 
 

Online splin

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Re: Ultra Precision Reference LTZ1000
« Reply #803 on: February 06, 2015, 05:32:17 pm »
Coincidentally I asked for a quote for Edwin's resistors a few days ago and thought I would post the reply (with permission) as it does provide some more information and pricing which may be of interest to others here:


Hello Mr. xxxxx,

Thank you for your inquiry, your request is a bit complicated for a simple reply but I'll try to keep it to a short novel.  All of my resistors are rated to military temperature range so a lab environment would be quite soft and 0 ±3PPM/°C TCR is standard for nearly all of my resistors.  I presume you would prefer the resistor values called out by Linear Tech as these have proven to be the best values that work, only the heater value may need to be tweaked if the units are operated at elevated temperatures, the LTZ must always be above the maximum expected ambient temperature to maintain Vref.  I am currently manufacturing these sets for other customers with minor variations in heater resistor values.  ±0.1% tolerance is quite sufficient for those resistors.

Your home lab standards, 1 ohm, at the moment is a bit difficult as very low TCR alloy in larger diameters is a hit or miss even today, I just made some 10 ohm resistors for a customer with the 'best' low TCR wire I have at that big of a size, its TCR is slightly higher than I normally accept (by about 10%) but I can't always get the TCR I want.  Basically what this means is that the final TCR batch range may be shifted by 0.3PPM/°C, not much really.  While it is not impossible to make a 1 ohm resistor from this stock, it will be quite difficult as the length of wire will be quite short, 1.5" and at 0.010" diameter, not much to work with.  Unfortunately, trying to parallel multiple low ohm resistors and keep reasonably close tolerance and particularly low TCR is very tricky, a problem I was working on for the Bob Pease project that was mentioned in the forum threads.  I can try and make a 1 ohm resistor from this stock but I'm not real sure how it would turn out.  The 100 ohm is no problem nor the 10K, I have made working standards with 0 ±10PPM tolerance from 100 ohms up to 10M.  At low ohm values, lead resistance becomes very significant, small variations in the lead spacing will cause significant measurement errors.  As a point of interest, transfer standards (also known as working standards) have a TCR of 0 ±5PPM/C° at ?100?, higher than my resistors.

I haven't made any real low ohms in several years, I work mainly with the Evanohm alloys and they usually are not available (easily) in larger sizes and low TCRs unfortunately, I'm told it is a quirk of the alloy, the smaller the diameter, the lower the TCR possible, an inverse relationship.  Given the current circumstances, any resistance below about 10 ohms is considered on request, it is not so much that I don't know how to make them, it is a matter of getting the necessary materials.  At this time I generally decline making resistors below 1 ohm.

A dozen 1K resistors is easy, tolerance is no problem, quite easy, even ±0.005%.

Long term stability is specified at 0 ±5PPM/year, data indicates the actual 'drift' is < 2 PPM/year.  At rated power, rated temperature range, drift is 0 ±10PPM/year or less.

A website is under construction as are new data sheets.

Approximate pricing, standard TCR, 0 ±0.1%:

Value    1-9       11-24
1R        $8.10    $6.08
100R   $6.85    $5.14
120R   $6.85    $5.14
1K        $6.34    $4.76
10K      $7.28    $5.46
12.5K   $7.43    $5.57
70K      $8.25    $6.19

For 1K,     ±0.1%, <= 1PPM/°C, quantity of 12, each: $6.76
For 1R,     ±0.1%, <= 1PPM/°C, quantity of 1, each $10.10
For 100R, ±0.1%, <= 1PPM/°C, quantity of 1, each $8.85

Note, selection of TCR is labor and time intensive, it is likely that the batch will be close to your TCR limit anyway, unless you are sure you really need such selection, I would recommend accepting the straight production run.

My 242D resistance bridge at 1 ohm, has an accuracy of better than 5 PPM, an uncertainty of 0.5PPM.

Quote based on using my 805 style which is the same as the often noted 8e16 from Rhopoint, 0.250" D x 0.500" L, measurement spacing is standard 0.375" from resistor body (1.25" C-C).  There are no exact equivalent resistors to mine, only in general terms and physical dimensions, electrically no one else can claim the same specifications or performance.

If the envelope meets requirements, the International first class package service rate would be approximately $10, the International priority package rate would be approximately $25.  The paperwork requires an address and specific details to get a more exact rate.

Best regards,

Edwin G. Pettis

Pettis Engineering / Ultrohm Plus
125 Vista Grande Dr.
Grand Junction, CO  81507-1427
1-970-242-4929
pettiseng@q.com






Hi,

I'm interested in purchasing some of your precision resistors. I understand that firm pricing probably depends on the precise order so approximate pricing will be Ok. for now.

These would all be for lab use so TCs below 10C or over 35C may be greater.

I'd like between 1 and 4 sets of resistors for an LTZ1000 reference; standard 0 to +3ppm parts should be OK.

I am also interested in some resistors for use as home lab 'standards'. The number obviously depends on pricing but at least 1R, 100R and 10K would be required. Are you still able to supply selected, < 1ppm, parts? If 1R is not available in < 3ppm TC, could you quote for the minimum number of paralleled resistors that would achieve 1R, < 3ppm and < 1ppm? 1% tolerance would be acceptable but I would like to know the measured value. What would be the measurement uncertainty please?

Are you able to supply low value, < 10mohm 10W resistors? If so what would the be the price and specification?

Could you supply a set of 12, approximately 1k resistors matched to 1% or better with TCs matched to < 1ppm? What if they were matched to .1%?

How much would shipping to the UK cost for 20 resistors?

Do you have a web site?

Do you have any data available on long term, room temperature stability?

Thanks,
    xxxxxxx
 

Offline HighVoltage

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Re: Ultra Precision Reference LTZ1000
« Reply #804 on: February 06, 2015, 08:08:25 pm »
What about equipment imported from another EU country?

Very stupid but within the EU you can buy gear without CE Mark with no problems, probably because this is not handeled as an import.

Correct, anything from an EU country is not handled by customs. Sometimes I have items shipped to a friend in the  Netherlands, where the customs is much more relaxed than in Germany. But I found a different way for gear without CE marking. If you have a customs import number in Germany (EORI) and you make a statement that this gear is for research and development (Forschung und Entwicklung) then the German customs will release it to you on your own risk and you have to sign a release form. But in any case it is a hassle.

Another great way to bypass German customs has worked a few times for me in the last few month. Just tell the seller to write on the custom forms: "Adult Plastic Toys" and suddenly it is delivered to your house without anyone from customs touching it.
 
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Offline Edwin G. Pettis

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Re: Ultra Precision Reference LTZ1000
« Reply #805 on: February 06, 2015, 08:30:25 pm »
High Voltage,

Adult plastic toys.....that is hilarious!  My resistors would fit into just the right size box for that trick!
 

Offline macfly

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Re: Ultra Precision Reference LTZ1000
« Reply #806 on: February 07, 2015, 09:32:26 am »
Hi voltnuts,

problems with the customs at import to the EU ?

That's really unbelievable for me. During the past 14 years I bought nearly all my
test gear in the U.S. and never had any problem with CE marking.
My last buy was october last year.

Perhaps I am a lucky guy .... ::)

Regards,

macfly
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Online bingo600

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Re: Ultra Precision Reference LTZ1000
« Reply #807 on: February 07, 2015, 02:12:24 pm »
I haven't had any probs. with CE markings either here in DK.

Only customs , and i don't even think "Adult toys" would slip by , as DK-Mail can claim the 20€ in fee for every package that's above 10€.

I even had a package once bought for 12$ from an ebay seller , but DK-Mail (Customs) claimed i had to prove the value by sending them a print of the paypal transaction.

They really want the 20€ in fee.

/Bingo
 

Offline janaf

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Re: Ultra Precision Reference LTZ1000
« Reply #808 on: February 08, 2015, 07:50:24 pm »
The Edwin P resistors, I'm in for three sets if there is a group order.
3x120R
3x1K
3x12K5
6x70K
If it gets too complicated, I can order directly from him.

Jan
my2C
Jan
 

Offline Andreas

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Re: Ultra Precision Reference LTZ1000
« Reply #809 on: February 08, 2015, 10:23:43 pm »
Hello Ken,

do you have a higher resolution photo of the chip?
From the first view it looks rather different from the LTZ chip.

With best regards

Andreas
 

Offline babysitter

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Re: Ultra Precision Reference LTZ1000
« Reply #810 on: February 09, 2015, 06:09:19 am »
<guessing>
By the looks of it I believe that it is a stacked, combined and averaged bunch of sources until its figured out better.
Even probing the single contributors and disconnecting the bad apples is possible IMHO, or the single cells might be prepared to have different tempcos and then select them so they cancel.
</guessing>
Or does somebody have a better interpretation of this l.q. photo?


« Last Edit: February 09, 2015, 06:11:30 am by babysitter »
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Offline Andreas

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Re: Ultra Precision Reference LTZ1000
« Reply #811 on: February 09, 2015, 07:09:49 am »
<guessing>
By the looks of it I believe that it is a stacked, combined and averaged bunch of sources until its figured out better.
Even probing the single contributors and disconnecting the bad apples is possible IMHO, or the single cells might be prepared to have different tempcos and then select them so they cancel.
</guessing>
Or does somebody have a better interpretation of this l.q. photo?

For me it looks like having 16 references all in parallel on LTFLU.

Similar to the LTZ1000 where the transistors Q1 + Q2 are splitted
into 4 elements each staggered in 45 degree arangement.

The tempco on LTFLU will most probably be adjusted by adjustment of the zener current.
Usually these parts are sold as a complete RefAmp-Set (the reference + the proper adjusted resistors).

With best regards

Andreas
 

Offline richiem

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Re: D-105 DCV standard test results
« Reply #812 on: February 09, 2015, 07:36:26 am »
For those interested who haven't visited the D-105 voltage standard thread, the one I ordered arrived, and I posted some brief results of testing there; look for my post near the bottom of page 15:

https://www.eevblog.com/forum/testgear/calibratory-d-105-dc-precision-voltage-reference-standard/210/
 

Offline TiN

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Re: Ultra Precision Reference LTZ1000
« Reply #813 on: February 09, 2015, 11:12:27 am »
In case anyone miss, I have two references for sale.
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Online Dr. Frank

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Re: Ultra Precision Reference LTZ1000
« Reply #814 on: February 09, 2015, 11:41:43 am »
Just in case anyone is interested, here is a photo of a Linear-Tech LTFLU-1ACH with the top of the can cut off:




Hi Ken,

I've compared this chip with the known LTZ1000 chip..
This one, of the presumed LTFLU, looks very strange, and I especially could not find any resemblance to the LTZ1000 chip, although the buried zener should be identical, acc. to Bob Dobkin.

Therefore, are you sure, that this is not a photo of a fake chip?

Frank
 

Offline babysitter

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Re: Ultra Precision Reference LTZ1000
« Reply #815 on: February 09, 2015, 04:10:00 pm »
I am in the process of setting up a dedicated webspace used for voltage and resistance standards. I am not yet behind the idea stage, but maybe I am making progress with the community.

http://wildvolttaming.schaffenburg.de is the temporary location.

I think about using a Wiki-Style to have a "public device history file", with a unique ID assigned to every device.
The idea is to stick a QR code plaque to the Device so the hosts can see the history of their guest devices and add their own results to it.
The home labs can have a Wiki page there, too. Maybe later online comparison tools will be available.
This will support cross-comparison of hobbyists standards.

Does this idea get some love here?
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Offline quarks

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Re: Ultra Precision Reference LTZ1000
« Reply #816 on: February 09, 2015, 08:42:51 pm »

I've heard stories [or fables] that *some* very old Fluke 732A's hold the volt to +/-0.1ppm per year.   I don't know if this is true, but if I owned one of those, you would have to use dynamite to get it out of my hands...

So, some projects that have been "stewing" in my lab are:
  • Poor-man's primary voltage transfer standard [based on LTZ1000(A)]
  • Poor-man's voltage transfer device
  • Poor-man's multi-junction thermal converter for AC/DC transfers
  • Poor-man's resistance standards [1R, 10R, 100R, 1K, 10K, 100K, 1M, 10M, 100M, 1G]
  • Poor-man's resistance synthesizer [that uses the above resistors to get any value]
  • Poor-man's direct current comparator bridge for low resistance measurement
  • Poor-man's electrometer for high resistance measurement
  • Poor-man's calibrator for DCV, ACV, DCI, ACI
  • Poor-man's automatic LCR bridge
  • (and a few others that are still in the idea stage)
There's enough there to keep me busy for a very lonnnnnnnng time...

Almost anything on your list is/was also on my list and probably on many others list too.
But I wonder what you mean by "Poor-man's ...".
Can you share what accuracy and stability you like to achive or find good enough for your listed projects?
If some is DIY, what are your candidates for the parts?

To make a start, for DIY resistance standard I started to select and test parts.
The top canditates (I already have) are from Isabellenhuette, Burster, VPG and Caddock. Because I can measure the values with quite good accuracy myself, I did not look for much better than 0.01% types.  I mainly care for low TCR and long time stability.

So far I have not really managed a good 1Ohm solution and nothing adequate for 100 M and 1 GOhm.

Maybe we should open a new thread for this.
« Last Edit: February 09, 2015, 09:06:36 pm by quarks »
 

Offline janaf

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Re: Ultra Precision Reference LTZ1000
« Reply #817 on: February 09, 2015, 10:44:28 pm »
Here are some results from measurements I made on the heaters of two LTZ1000A
my2C
Jan
 

Offline quarks

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Re: Ultra Precision Reference LTZ1000
« Reply #818 on: February 10, 2015, 04:34:26 am »
Anyway, yes, I agree, these are probably better discussed in another thread.  I planned on launching some threads with the "[Metrology] " prefix, so that they would be easier to search for.

Very good, please do so
 

Offline janaf

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Re: Ultra Precision Reference LTZ1000
« Reply #819 on: February 10, 2015, 11:09:28 am »
Here is a diagram for setting the temperature of the LTZ1000A. The values are calculated from datasheet, not measured. I hope it's useful to someone.
my2C
Jan
 

Offline richiem

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Re: Ultra Precision Reference LTZ1000
« Reply #820 on: February 13, 2015, 06:57:59 am »
I have an HP 3458A ref board, REV A 03458-66509. Can anyone confirm whether this board rev has an LTZ1000 or 1000A? The HP part number for the LTZ is 1826-1860 -- I have a good HP X-ref, but this part # isn't in it. I've put a 12.1K metal foil resistor in the place of the 15k Vishay for temp control. This value would be OK for the 1000, but possibly marginal for the 1000A. Solid info will be very welcome!
 

Online Dr. Frank

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Re: Ultra Precision Reference LTZ1000
« Reply #821 on: February 13, 2015, 07:35:49 am »
Hi Dick,
As far as commonly known, HP used the A version only, due to the nominal 95•C.
12.1k sets  the oven to about 45•C but the interior temp already will be 35.. 40•C at least, so the difference is much too small, as the A version requires 10•C overhead plus some additional regulation margin, at least.
The self heating of the 3458A adds  13•C to room temperature ,plus 5 •C more for a dirty filter, plus 10•C if placed in a rack.
Therefore, I always recommend to set the temp to 65•C , ie 13k, or 100k in parallel to the 15k, if the lab is not warmer than 30•C

The reference ages only, when it is powered.
Therefore, drifts < 1ppm/year can be expected on 65•C,  if the 3458A is not running continuosly.

If you use the ref board outside the 3458A, then 12.5k is the correct value, for about 55•C.
45•C is a little bit critical for the A version, otherwise you have to make sure, that the ambient temperature will not exceed 30•C. And there should be a thermal shielding around the TO 99, which should allow heat exchange, ie not too good an isolating material.





Frank


« Last Edit: February 13, 2015, 08:53:53 am by Dr. Frank »
 

Offline ltz2000

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Re: Ultra Precision Reference LTZ1000
« Reply #822 on: February 13, 2015, 10:32:25 am »
I've heard stories [or fables] that *some* very old Fluke 732A's hold the volt to +/-0.1ppm per year. I don't know if this is true, but if I owned one of those, you would have to use dynamite to get it out of my hands...

True. Sometimes it happens that the drifts of the zener and the amplifier (resistors) are approximately the same magnitude but opposite direction resulting a very low net drift. However that is not "real" stability because the individual drifts can be and usually are still quite high. Would be risky to assume the net drift to stay constant forever because it is very sensitive to changes in individual drifts.
 

Offline quarks

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Re: Ultra Precision Reference LTZ1000
« Reply #823 on: February 13, 2015, 03:11:31 pm »
I have an HP 3458A ref board, REV A 03458-66509. Can anyone confirm whether this board rev has an LTZ1000 or 1000A? The HP part number for the LTZ is 1826-1860...

that is an interesting question. I have several boards with the same revision as yours and I read original LTZ1000ACH and also 1826-1860 on older ones (which is probably only printed on for HP). In the schematic (see att.) it says clearly LTZ1000 and there also is R417 200k which should be 400k, according to LT reference design. But even more interesting is, that it should not be populated when LTZ1000A is used, but the resistor is on all boards I have seen so far.

https://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/msg440601/#msg440601

I wonder if there is a good explanation.  Would be great if anyone could share knowledge.
« Last Edit: February 13, 2015, 03:16:11 pm by quarks »
 

Offline branadic

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Re: Ultra Precision Reference LTZ1000
« Reply #824 on: February 15, 2015, 11:07:24 am »
I found 0.3-0.8ppm/°C Precision zener-based references today. Maybe of interest for someone?

« Last Edit: February 15, 2015, 12:58:05 pm by branadic »
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