[volt-nuts] (New to me) 3458A Trivia

[Bill Gold]

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