When I refer to a "Golden" 3458A is simple mean that over the years I have gone through dozens of 3458A's and in that time have found a few truly exceptional instruments that I and others who have them often refer to as "Golden". The biggest difference I see unit to unit is not ref/zenner but the A/D. A really good "Golden" 3458A can often stay at 5@10-8 (a few counts on the eighth digit) connected to a PJVS or good 732B for weeks or even months at a time. If you are lucky enough to have one don't ever let it go. So my thought was with advances since 1988 especially in A/D's will most/or a greater percentage of these redesigns be golden. Cheers;
Tom Knox 303-554-0307 [email protected] "Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein ________________________________ From: volt-nuts <[email protected]> on behalf of Frank Stellmach <[email protected]> Sent: Saturday, October 26, 2019 12:39 PM To: [email protected] <[email protected]> Subject: [volt-nuts] HP3458A - Black Edition @ Poul-Henning: It's improbable that we'll see improved specs. The presentation of the Black Edition already happened end of May, and the validation obviously was already running. The description @ meilhaus already claims that no change in spec. will happen, and the linked Black Edition specs are really identical. @ David and Bob: RoHS is a European requirement only, and may not (yet) apply to other markets. KS obviously has stocked a bunch of lead containing units (they called it EU3458A) in their own premises before the exemption expired, and as this stock would be depleted later, they needed to design a lead free unit - initially for the EU market only. I suppose they will sell the white version outside the EU for several years, until their old component stock is depleted also. I wonder what will happen to the EU34420A, which has the same problem, but lead free soldering might pose greater problems, due to e.m.f. @ nV level. @ Tom: I can't tell anything about Golden Units, as I only own a regular, white HP3458A from 2001, which still performs better than specification.. +1.8ppm drift only, over 9 years for DCV, and Ohm is also much more stable than specification, as far as I can judge. Ok, the trick is, that it does not run 24/365, and my LTZ reference board is set to ~ 65°C. Concerning the internal A/D converter clock, there are several papers about AC metrology, especially on AC power measurements, where the PTB improved the accuracy greatly by optically linking the internal clock to the rear of the 3458A, to mitigate the 10 or 100ns (?) clock phase jitter. See also Rado Lapuh, Sampling With 3458A, page 149. A practical schematic is not published, so it's very appreciated that you provide one, but a description, how to apply this clock would be necessary. Frank _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there.
