Most Fluke high-precision units used a Motorola buried zener + transistor reference in a metal can -- I forget the Moto part number, but they are pretty much unobtanium now. Units using this reference include, from personal knowledge, the 731B, 732A, 335B/C/D, 5440A/B, 8505/8506, 510A. In some units the reference device is in an oven, in others, notably the 8505/8506 and 510A, they are just at the internal case temperature, but all cleverly use the transistor to provide first-order temp comp. When ovenized together with the various voltage dividers, the part is very, very good, as shown by the 732A and 5440A/B, which can hold sub-ppm accuracies over periods of weeks to months. I personally found the 732As to be stable through many power-off/-on cycles, so I didn't use the batteries. The need to ship them hot is unnecessary, in my opinion, if 1ppm stability/accuracy is the goal. Don't know about the 731B. Demian's offer to ship 731Bs around is very helpful, and would be a great adjunct to the original proposal. This sharing of standards is something that I've wanted to see for quite a while, but when I owned the two 732As and 5440B, that just wasn't practical, and shipping high-res DMMs around didn't make much sense either. Many thanks to Bob for carefully evaluating design decisions and for embarking on this project. Now if someone could just send a 0.1ppm 10k resistor around, too, life would be great. Dick Moore On Aug 31, 2011, at 5:00 AM, volt-nuts-request@febo.com wrote: > > Message: 4 > Date: Tue, 30 Aug 2011 18:58:26 -0700 > From: "Demian Martin" <demianm_1@yahoo.com> > To: "'Bob Smither'" <smither@c-c-i.com> > Cc: volt-nuts@febo.com > Subject: Re: [volt-nuts] Traveling Standards > Message-ID: <00ed01cc6781$792a01e0$6b7e05a0$@com> > Content-Type: text/plain; charset="us-ascii" > > Bob: > To make a real PPM standard has so many technique pitfalls that it may be a > really frustrating experience. The late Jim Willians wrote something about > this in a article on checking precision DAC's. Even with the best stuff a > real climate controlled environment is more than most of us are able to do. > If you look at the manuals and construction efforts for these things there > is a lot of experience in details that's hard to just copy. Even the circuit > layouts and managing the thermocouples in all the connections is not > trivial. Here is a good starting point for understanding it: > http://cds.linear.com/docs/Application%20Note/an74f.pdf > > Here is an alternate offer I'll make. I just checked and I have 3 Fluke > 731b's that I'll be happy to provide for travelling standards. They are > doing nothing but occupying space on a shelf for now. I also have a 732A, a > Prema DVM and a Fluke 8506a, all of which use LTZ1000 references. Those > three have tracked each other within 50 ppm for the last 5 years without > attention. Probably none have been calibrated in the 21'st century and only > the Flukes have a common origin. Prema makes their own JJ standards. I'll > fire up the 3 731b's and check them against the trio to get things started. > I'll get them boxed in a nice reusable shipping case if you will pick up the > shipping to start this off. They may need service (the batteries are > probably shot by now), I'll leave that to you. I don't have time for more > with my "day" job. > > If this is interesting send me a note directly and I'll get it started. > Demian > > Date: Mon, 29 Aug 2011 22:52:24 -0500 > From: Bob Smither <smither@c-c-i.com> > To: Discussion of precise voltage measurement <volt-nuts@febo.com> > Subject: Re: [volt-nuts] Traveling Standards > Message-ID: <4E5C5E78.6020109@c-c-i.com> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > Fellow Voltage Fans, > > To review - I would like to have a lab standard here that I can trust to > 10 ppm or better to use to calibrate my expanding collection of > voltmeters. I have proposed to built a portable standard that I will > ship to participating volt nuts on this list who will record their > readings of the standard and share those readings with the list. > > I have designed a Traveling Standard that incorporates two references > (an LM199AH and a MAX6350E) along with an LM34 to measure the > temperature of the MAX6350 (the LM34 is glued to the top of the MAX6350. > > The schematic is attached to this page: > > http://www.c-c-i.com/TS > > Following suggestions on this list (thanks!) I will use an external > "wall wart" supply for the input 24 Volts. This reduces any shift > caused by the line regulation of the three terminal regulator. > > My design notes are included on the above page. > > I have constructed a bread board of the circuit on a plugboard. I will > move the circuit to a printed circuit version after some testing. > > Some preliminary readings from the breadboard of the LM199AH part are > noted on this page: > > http://c-c-i.com/node/121 > > Note that these readings are taken with an HP3455A which has not been > calibrated since I bought it new. I would expect the accuracy to be no > better than .01% and may be much worse. > > My plan is to mount the printed circuit board version in a short length > of 2" PVC pipe with connectors for the three outputs. > > After the printed circuit board version is aged some it will be ready to > ship. > > Are there any more on the list that would be willing to make a > measurement of the Traveling Standard? > > I will collect the readings that we collectively get on the TS and make > them available to the list. I anticipate that with some experience we > can all benefit from having this TS well aged and with a well known > output voltage. > > I will handle the shipping - all I ask is that you take careful > measurements and provide them to me, then return the unit. > > Thanks! > > **************** > > > > > ------------------------------ > > Message: 5 > Date: Wed, 31 Aug 2011 01:24:25 -0400 > From: "Charles P. Steinmetz" <charles_steinmetz@lavabit.com> > To: Discussion of precise voltage measurement <volt-nuts@febo.com> > Subject: Re: [volt-nuts] Traveling Standards > Message-ID: <20110831052432.5D80111BCE2@karen.lavabit.com> > Content-Type: text/plain; charset="us-ascii"; format=flowed > > Demian wrote: > >> To make a real PPM standard has so many technique pitfalls that it may be a >> really frustrating experience. * * * >> If you look at the manuals and construction efforts for these things there >> is a lot of experience in details that's hard to just copy. Even the circuit >> layouts and managing the thermocouples in all the connections is not >> trivial. Here is a good starting point for understanding it: >> http://cds.linear.com/docs/Application%20Note/an74f.pdf > > Linear Technology's Application Notes AN42, AN82, AN86, and AN124 > also contain valuable information on the topic. The Linear > Technology Design Note DN229 discusses reference hysteresis, > including the thermal shock from soldering. > >> I also have a 732A, a Prema DVM and a Fluke 8506a, all of which use >> LTZ1000 references. > > I believe the 732A uses a common-substrate zener + transistor in an > oven assembly that contains the whole reference circuit. > > Best regards, > > Charles > > > > > > > > > > ------------------------------ > > _______________________________________________ > volt-nuts mailing list > volt-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > End of volt-nuts Digest, Vol 24, Issue 37 > *****************************************

Hi Dick, Yes Demian's offer is quite nice. He really only needs to send one, though, not all three. The absolute value is unimportant only that it be stable. The first pass would let everyone know how they place with everyone else in measuring its value. Bill....WB6BNQ Dick Moore wrote: > Most Fluke high-precision units used a Motorola buried zener + transistor reference in a metal can -- I forget the Moto part number, but they are pretty much unobtanium now. Units using this reference include, from personal knowledge, the 731B, 732A, 335B/C/D, 5440A/B, 8505/8506, 510A. In some units the reference device is in an oven, in others, notably the 8505/8506 and 510A, they are just at the internal case temperature, but all cleverly use the transistor to provide first-order temp comp. > > When ovenized together with the various voltage dividers, the part is very, very good, as shown by the 732A and 5440A/B, which can hold sub-ppm accuracies over periods of weeks to months. I personally found the 732As to be stable through many power-off/-on cycles, so I didn't use the batteries. The need to ship them hot is unnecessary, in my opinion, if 1ppm stability/accuracy is the goal. Don't know about the 731B. > > Demian's offer to ship 731Bs around is very helpful, and would be a great adjunct to the original proposal. This sharing of standards is something that I've wanted to see for quite a while, but when I owned the two 732As and 5440B, that just wasn't practical, and shipping high-res DMMs around didn't make much sense either. > > Many thanks to Bob for carefully evaluating design decisions and for embarking on this project. Now if someone could just send a 0.1ppm 10k resistor around, too, life would be great. > > Dick Moore > > On Aug 31, 2011, at 5:00 AM, volt-nuts-request@febo.com wrote: > > > > > Message: 4 > > Date: Tue, 30 Aug 2011 18:58:26 -0700 > > From: "Demian Martin" <demianm_1@yahoo.com> > > To: "'Bob Smither'" <smither@c-c-i.com> > > Cc: volt-nuts@febo.com > > Subject: Re: [volt-nuts] Traveling Standards > > Message-ID: <00ed01cc6781$792a01e0$6b7e05a0$@com> > > Content-Type: text/plain; charset="us-ascii" > > > > Bob: > > To make a real PPM standard has so many technique pitfalls that it may be a > > really frustrating experience. The late Jim Willians wrote something about > > this in a article on checking precision DAC's. Even with the best stuff a > > real climate controlled environment is more than most of us are able to do. > > If you look at the manuals and construction efforts for these things there > > is a lot of experience in details that's hard to just copy. Even the circuit > > layouts and managing the thermocouples in all the connections is not > > trivial. Here is a good starting point for understanding it: > > http://cds.linear.com/docs/Application%20Note/an74f.pdf > > > > Here is an alternate offer I'll make. I just checked and I have 3 Fluke > > 731b's that I'll be happy to provide for travelling standards. They are > > doing nothing but occupying space on a shelf for now. I also have a 732A, a > > Prema DVM and a Fluke 8506a, all of which use LTZ1000 references. Those > > three have tracked each other within 50 ppm for the last 5 years without > > attention. Probably none have been calibrated in the 21'st century and only > > the Flukes have a common origin. Prema makes their own JJ standards. I'll > > fire up the 3 731b's and check them against the trio to get things started. > > I'll get them boxed in a nice reusable shipping case if you will pick up the > > shipping to start this off. They may need service (the batteries are > > probably shot by now), I'll leave that to you. I don't have time for more > > with my "day" job. > > > > If this is interesting send me a note directly and I'll get it started. > > Demian > > > > Date: Mon, 29 Aug 2011 22:52:24 -0500 > > From: Bob Smither <smither@c-c-i.com> > > To: Discussion of precise voltage measurement <volt-nuts@febo.com> > > Subject: Re: [volt-nuts] Traveling Standards > > Message-ID: <4E5C5E78.6020109@c-c-i.com> > > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > > > Fellow Voltage Fans, > > > > To review - I would like to have a lab standard here that I can trust to > > 10 ppm or better to use to calibrate my expanding collection of > > voltmeters. I have proposed to built a portable standard that I will > > ship to participating volt nuts on this list who will record their > > readings of the standard and share those readings with the list. > > > > I have designed a Traveling Standard that incorporates two references > > (an LM199AH and a MAX6350E) along with an LM34 to measure the > > temperature of the MAX6350 (the LM34 is glued to the top of the MAX6350. > > > > The schematic is attached to this page: > > > > http://www.c-c-i.com/TS > > > > Following suggestions on this list (thanks!) I will use an external > > "wall wart" supply for the input 24 Volts. This reduces any shift > > caused by the line regulation of the three terminal regulator. > > > > My design notes are included on the above page. > > > > I have constructed a bread board of the circuit on a plugboard. I will > > move the circuit to a printed circuit version after some testing. > > > > Some preliminary readings from the breadboard of the LM199AH part are > > noted on this page: > > > > http://c-c-i.com/node/121 > > > > Note that these readings are taken with an HP3455A which has not been > > calibrated since I bought it new. I would expect the accuracy to be no > > better than .01% and may be much worse. > > > > My plan is to mount the printed circuit board version in a short length > > of 2" PVC pipe with connectors for the three outputs. > > > > After the printed circuit board version is aged some it will be ready to > > ship. > > > > Are there any more on the list that would be willing to make a > > measurement of the Traveling Standard? > > > > I will collect the readings that we collectively get on the TS and make > > them available to the list. I anticipate that with some experience we > > can all benefit from having this TS well aged and with a well known > > output voltage. > > > > I will handle the shipping - all I ask is that you take careful > > measurements and provide them to me, then return the unit. > > > > Thanks! > > > > **************** > > > > > > > > > > ------------------------------ > > > > Message: 5 > > Date: Wed, 31 Aug 2011 01:24:25 -0400 > > From: "Charles P. Steinmetz" <charles_steinmetz@lavabit.com> > > To: Discussion of precise voltage measurement <volt-nuts@febo.com> > > Subject: Re: [volt-nuts] Traveling Standards > > Message-ID: <20110831052432.5D80111BCE2@karen.lavabit.com> > > Content-Type: text/plain; charset="us-ascii"; format=flowed > > > > Demian wrote: > > > >> To make a real PPM standard has so many technique pitfalls that it may be a > >> really frustrating experience. * * * > >> If you look at the manuals and construction efforts for these things there > >> is a lot of experience in details that's hard to just copy. Even the circuit > >> layouts and managing the thermocouples in all the connections is not > >> trivial. Here is a good starting point for understanding it: > >> http://cds.linear.com/docs/Application%20Note/an74f.pdf > > > > Linear Technology's Application Notes AN42, AN82, AN86, and AN124 > > also contain valuable information on the topic. The Linear > > Technology Design Note DN229 discusses reference hysteresis, > > including the thermal shock from soldering. > > > >> I also have a 732A, a Prema DVM and a Fluke 8506a, all of which use > >> LTZ1000 references. > > > > I believe the 732A uses a common-substrate zener + transistor in an > > oven assembly that contains the whole reference circuit. > > > > Best regards, > > > > Charles > > > > > > > > > > > > > > > > > > > > ------------------------------ > > > > _______________________________________________ > > volt-nuts mailing list > > volt-nuts@febo.com > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > > > End of volt-nuts Digest, Vol 24, Issue 37 > > ***************************************** > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.