Re: [volt-nuts] HP 3457A calibration?
Someone pointed out in the comments that his DMM was probably calibrated once or twice at the most. >From looking at what is on this guys shelf, he has way more money than I do to spend on test equipment. I'm jealous :-) Speaking of too much test equipment, that guy Dave who does the EEVBlog videos also has a lab to drool over. I don't know what he does for a living, but he seems to be more knowledgeable than the guy from South Africa (who is also long winded and boring). As for the "cheaper" solution, I just bought a 3457A. I expect to see it this week. After checking it out for a bit, I'll be sending it to Agilent. Although it may seem ridiculous to spend $200 getting it calibrated, I figure that I'd be better off having Agilent do it this time, so I know where I stand. I'll have to read the cal counter before and after sending it to Agilent. I'll let you know the results. If the battery looks original, I'll have to change that out before sending it for calibration. I know that I have to keep the SRAM powered, so I don't loose the data already there. Joe Gray W5JG On Mon, Aug 19, 2013 at 7:59 PM, J. L. Trantham wrote: > Interesting video. > > His 'cal certificate' shows no data other than 'in tolerance' and the > 'standards' used to established that. > > He also makes a point of the 'calibration counter'. > > On the 3458A that I was able to 'kill' the 'cal RAM', the 'cal counter' was > at '1' when I received it. When I finished doing my 'home cal' on a > 'blank' > 'cal RAM', the 'cal counter' was about 20 or so. It appears that every > measurement that is calibrated increments the 'cal counter'. > > I don't recall how many ranges the 3457A has but add them all up and that > is > what I would expect the 'cal counter' to increment by once you finish a > 'home cal'. > > Since Agilent does all this via HPIB (at least that's what I think), it > increments the 'cal counter' only by '1' step. > > I would opt for a 'cheaper' 'seems to be working' 3457A then send it to > Agilent for their calibration rather than spend extra for someone else's > calibration. > > Joe > WB4BPP > > -Original Message- > From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On > Behalf Of Joseph Gray > Sent: Monday, August 19, 2013 8:20 PM > To: Discussion of precise voltage measurement > Subject: [volt-nuts] HP 3457A calibration? > > Recently, we were discussing where to get a DMM calibrated. Someone > mentioned an ebay seller in Albuquerque who had their meters calibrated > across town by a company with a similar name. > > I am currently watching a YouTube video about the HP 3457A. At around 7 > minutes, take a look at the calibration certificate when he holds it up. > > http://www.youtube.com/watch?v=HfxpJCdgVwc > > Joe Gray > W5JG > ___ > 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. > > ___ > 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. > > ___ 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.
[volt-nuts] Fluke 8842A
I just got a totally dead 8842A. After I repair it, I was thinking of perhaps using it as the basis of a homemade 10 VDC reference. It has one of those Motorola buried zener references in it. There is a test point for the 7 VDC reference. I'll have to look at the schematics for the 731 to see how Fluke did things. Joe Gray W5JG ___ 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.
Re: [volt-nuts] HP 3457A calibration?
Interesting video. His 'cal certificate' shows no data other than 'in tolerance' and the 'standards' used to established that. He also makes a point of the 'calibration counter'. On the 3458A that I was able to 'kill' the 'cal RAM', the 'cal counter' was at '1' when I received it. When I finished doing my 'home cal' on a 'blank' 'cal RAM', the 'cal counter' was about 20 or so. It appears that every measurement that is calibrated increments the 'cal counter'. I don't recall how many ranges the 3457A has but add them all up and that is what I would expect the 'cal counter' to increment by once you finish a 'home cal'. Since Agilent does all this via HPIB (at least that's what I think), it increments the 'cal counter' only by '1' step. I would opt for a 'cheaper' 'seems to be working' 3457A then send it to Agilent for their calibration rather than spend extra for someone else's calibration. Joe WB4BPP -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Joseph Gray Sent: Monday, August 19, 2013 8:20 PM To: Discussion of precise voltage measurement Subject: [volt-nuts] HP 3457A calibration? Recently, we were discussing where to get a DMM calibrated. Someone mentioned an ebay seller in Albuquerque who had their meters calibrated across town by a company with a similar name. I am currently watching a YouTube video about the HP 3457A. At around 7 minutes, take a look at the calibration certificate when he holds it up. http://www.youtube.com/watch?v=HfxpJCdgVwc Joe Gray W5JG ___ 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. ___ 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.
[volt-nuts] HP 3457A calibration?
Recently, we were discussing where to get a DMM calibrated. Someone mentioned an ebay seller in Albuquerque who had their meters calibrated across town by a company with a similar name. I am currently watching a YouTube video about the HP 3457A. At around 7 minutes, take a look at the calibration certificate when he holds it up. http://www.youtube.com/watch?v=HfxpJCdgVwc Joe Gray W5JG ___ 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.
Re: [volt-nuts] Fluke 732B
Yes, it was very cool to see the insides of the 732B. The older standards apparently ran at room temperature. The oven assembly looks like quite a bit of engineering went into it. The link that was provided to a Chinese site does have some interesting details about the entire Fluke reference series. However, using Google Translate, some of the images don't download. That makes it hard to follow the discussion, on top of the imperfect English translation. I had just read the Deaver paper a few days ago. It is interesting that the older 732A drift rates are clustered closer together than the 732B. You would think that with most of the circuit in an oven, the 732B would not show as much spread. Joe Gray W5JG On Mon, Aug 19, 2013 at 5:29 PM, Bill Gold wrote: > Joe: > > That was a very interesting teardown of the 732B on eevblog. The one > thing that this answered for me was if Fluke was using their "Reference > Amplifier" in all of the 732B production and Fluke did. > > If you look at a paper by David Deaver called "Predictability of Solid > State References" which he wrote, and you can download from the Fluke > website http://us.fluke.com/. you will see on page three of the paper > that he talks about the reference drifts of a number of 732Bs that were > checked over a period of time. Deaver talks about Motorola References and > Linear Technology References and that the Motorola's drift upwards while > the Linear Tech's drift downwards over time. Also look at Fig. 10. I was > assuming (wrongly of course as I see now) that Fluke had switched from the > "Reference Amplifier" to the LTZ1000 in the production of the 732B. Now I > see that it is just what company made the "Reference Amplifiers" for Fluke. > Of course the 4 legged device is a "Reference Amplifier" that they have > used for a least 25 years or more as the voltage reference in a lot of > their instruments. > > I have never seen a schematic of the super secret "oven assembly" but > you can probably bet that it looks a lot like the 732A but with a lot more > "black magic" built into it. I don't think that Fluke would ever expect > someone to fix this beyond the unit replacement level as I am sure that > this would require factory precedures far beyond anything that we could > muster in the field. Part of the black magic is adjusting the collector > current of the reference amplifier to obtain a zero TC around a very > limited range of operating temperatures. The digital adjustments also add > something inside the oven assembly, probably a DAC, and it would be > interesting what they are doing there, so a schematic would be interesting > to see. > > Anyway I will quit rambling. So many things to do, so little time. > > Bill > ___ > 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. > > ___ 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.
Re: [volt-nuts] Fluke 732B
Joe: That was a very interesting teardown of the 732B on eevblog. The one thing that this answered for me was if Fluke was using their "Reference Amplifier" in all of the 732B production and Fluke did. If you look at a paper by David Deaver called "Predictability of Solid State References" which he wrote, and you can download from the Fluke website http://us.fluke.com/. you will see on page three of the paper that he talks about the reference drifts of a number of 732Bs that were checked over a period of time. Deaver talks about Motorola References and Linear Technology References and that the Motorola's drift upwards while the Linear Tech's drift downwards over time. Also look at Fig. 10. I was assuming (wrongly of course as I see now) that Fluke had switched from the "Reference Amplifier" to the LTZ1000 in the production of the 732B. Now I see that it is just what company made the "Reference Amplifiers" for Fluke. Of course the 4 legged device is a "Reference Amplifier" that they have used for a least 25 years or more as the voltage reference in a lot of their instruments. I have never seen a schematic of the super secret "oven assembly" but you can probably bet that it looks a lot like the 732A but with a lot more "black magic" built into it. I don't think that Fluke would ever expect someone to fix this beyond the unit replacement level as I am sure that this would require factory precedures far beyond anything that we could muster in the field. Part of the black magic is adjusting the collector current of the reference amplifier to obtain a zero TC around a very limited range of operating temperatures. The digital adjustments also add something inside the oven assembly, probably a DAC, and it would be interesting what they are doing there, so a schematic would be interesting to see. Anyway I will quit rambling. So many things to do, so little time. Bill ___ 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.
