Teardown: Voltage Standards

[zlymex]

Summary before teardown




 - The years of release and stop are estimate. Correct me if anyone know the accurate.
 - Oven: small dot for chip level, large for board level
 - There are evidents indicating that the voltage of most LTZ1000 and LTFLU-1 go down with time while SZA263 go up.
 - The order of the teardown is roughly chronological
 - The order on the list is according to the annual drift(and the time of release of same)
 - The teardown will focus to the most important part: the 7V reference and the 7V to 10V conversion.
 - Of course I don't have the teardowns of all listed(the list is not complete on its own). If anyone has, contribute.
 - There is no release of new voltage standard for sometimes now, until recently by ADCMT, 'The highest performance 6900 in the world':
http://www.adcmt.com/news/press/press-2015/press20150624.html



Fluke 731A







One of the basic circuit.
If delete R3 and R4, connect neg input of the opamp to base of the refamp, then we get the simplest refamp circuit.


Fluke 731B





There are three major modifications compare to 731A
 - output current limiting circuitry added
 - use hermetic WW. Those WW became widely used by Fluke later
 - use SZA263 as refamp. This refamp became widely used by Fluke later



Fluke 732A
(See attachment)

There are some modifications compare to 731B
 - board ovenized.
 - use lead-acid batteries instead of NiCad.
 - small-sized hermetic WW were used
 - refamp protected by Q5(for later version of LTFLU-1, the protection is build-in)
 - formalize the output as 'series pass'
 - use 'binary' scheme on major part of the 10V adjustment, but not all.
The basic circuitry is not changed even for the designator

[zlymex]

Guildline 4400








Datron/Wavetek 4910
see attachment

[zlymex]

4910 continued




Fluke 732B










There are some modifications compare to 732A
 - more compact
 - battery: one 12V instead of four 6V

The crucial components unchanged. Those pair of hermetic WW contribute to most of the drift and there are many knock out 732B units because it.

[alanambrose]

Very nice, thanks for putting in all the work

Alan

[zlymex]

Datron/Wavetek/Fluke 7001










A lot of new technology used in it:
 - Low chip temperature to minimize drift
 - Taitanium-Nitrate(TaN) "statistical" resistor arrays
 - 8 bit DACs to adjust 10V
 - NiMH battery(10 AA)
 - Patented Hysteresis Safeguard
 - Patented high-isolation DC/DC Converter
 - Electronic(rather than electromechanical) switches were used
A practical approach to maintaining DC reference standards
www.elcal.ch/files/11749-eng-01-a.pdf

Strange enough, the teardown revealed that they use TDP1603 resistor array, the material Passivated nichrome instead of TaN.
www.vishay.com/docs/60045/tdp.pdf

(The End)

[quarks]

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[dr.diesel]

Most excellent   

[lowimpedance]

@ Zlymex
 Dont know how I missed this thread, but most excellent as usual. 
As for the Guildline 4400 It is also the same as the Statronics VS4 which was from a design developed at CSIRO.
I have a prototype and a VS4 (now operational again), will post some pics tomorrow.

[Vgkid]

On a related note, does snyone have any information on the koep transportable standards. I bought one on ebay, and it was stolen from the guys store .

[ManateeMafia]

I have a little info on the Koep standards. Attached are a couple of photos, I have the triple reference. Sorry, I need to take more pictures of mine and put them on xDevs. I have a few of the internal construction but each reference is potted.

There is also a datasheet for their zeners presumably the best were used in the standards.

I also have a scanned copy of the VTS4007 manual but it is too large to fit here but I will upload it to ko4bb.

Of note, the only one I know of that is in use is at IET labs. It is listed under their scope of accreditation. http://www.a2la.org/scopepdf/2073-01.pdf

[lowimpedance]

@ Zlymex
 Dont know how I missed this thread, but most excellent as usual. 
As for the Guildline 4400 It is also the same as the Statronics VS4 which was from a design developed at CSIRO.
I have a prototype and a VS4 (now operational again), will post some pics tomorrow.

Okay here are the photos of the VS4 and the NML01 prototype.
I see it looks like the Guildline version does not have the 1.018V outputs ?
The oven runs at approx 33 deg C. The heating 'elements' are the LM395

[zlymex]

@lowimpedance Very nice photo. Guildline also has the similar version called 4410, must be the same origin.

[lowimpedance]

@lowimpedance Very nice photo. Guildline also has the similar version called 4410, must be the same origin.

I was not aware of the Guildline versions, most interesting.
Forgot to mention the prototype only used 6 lm329s not the 8 as in the 'production units', also the precision card resistors were made by ESI iirc.

[manganin]

I was not aware of the Guildline versions, most interesting.

I see it looks like the Guildline version does not have the 1.018V outputs ?

There were two versions manufactured by Statronics in Australia, but distributed under the Guildline brand. The 4410 with 1.018V outputs and the economy 4400 without. The 4400 was identical to the 4410 except the front panel and the zener buffer op-amps and the 1V dividers not assembled on the printed circuit board.

Okay here are the photos of the VS4 and the NML01 prototype.

Your VS4 is the late version with the Guildline face lift (note the "grid" on the right side of the front panel), but Statronics branded. The original Statronics was not as pretty, see the photo attached.

[MegaVolt]

A little bit of beauty 732A