Speaking of the 03458-66529 reference board added to the HP 3458A by Fluke (before Fluke offered the 8508A), has anyone ever seen a schematic of that board or how Fluke could rate that reference at 2 ppm? One person on this forum theorized that by lowering the operating temperature of the LTZ1000A to around 70 degrees C, which is what the LTC device specification note recommends, this might have what was done to achieve the better drift specification. It was noted that HP was running the LTZ1000A at around 105 degrees C which might accelerate the aging rate. I lowered my references to around 70 C and they have seemed to be a little more stable when checked against the Fluke 732A DC Reference Standard. But I never started a project to follow up on this theory. Just another project to play with when I "get a round toit" Bill

I think the main thing they do is age and screen. On Tue, Oct 30, 2012 at 6:48 AM, Bill Gold <wpgold3637@att.net> wrote: > Speaking of the 03458-66529 reference board added to the HP 3458A by Fluke > (before Fluke offered the 8508A), has anyone ever seen a schematic of that > board or how Fluke could rate that reference at 2 ppm? One person on this > forum theorized that by lowering the operating temperature of the LTZ1000A > to around 70 degrees C, which is what the LTC device specification note > recommends, this might have what was done to achieve the better drift > specification. It was noted that HP was running the LTZ1000A at around 105 > degrees C which might accelerate the aging rate. I lowered my references > to around 70 C and they have seemed to be a little more stable when checked > against the Fluke 732A DC Reference Standard. But I never started a > project to follow up on this theory. Just another project to play with > when I "get a round toit" > 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. > -- John Phillips

Per my conversation with Gary Biermann, the 4 ppm and the 2 ppm units are the same as the 8 ppm units except they perform better. Purely a selection of best performers and nothing to do with a special circuit. I don't know about Fluke. Joe -----Original Message----- From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of John Phillips Sent: Tuesday, October 30, 2012 11:07 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] (New to me) 3458A Trivia I think the main thing they do is age and screen. On Tue, Oct 30, 2012 at 6:48 AM, Bill Gold <wpgold3637@att.net> wrote: > Speaking of the 03458-66529 reference board added to the HP 3458A by > Fluke (before Fluke offered the 8508A), has anyone ever seen a > schematic of that board or how Fluke could rate that reference at 2 > ppm? One person on this forum theorized that by lowering the > operating temperature of the LTZ1000A to around 70 degrees C, which is > what the LTC device specification note recommends, this might have > what was done to achieve the better drift specification. It was noted > that HP was running the LTZ1000A at around 105 degrees C which might > accelerate the aging rate. I lowered my references to around 70 C and > they have seemed to be a little more stable when checked against the > Fluke 732A DC Reference Standard. But I never started a project to > follow up on this theory. Just another project to play with when I "get a round toit" > 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. > -- John Phillips _______________________________________________ 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.