Sorry if too far off topic -Depending on the age of the 3458A if it uses the Dallas chips, SnapHat, or coin style battery. The older units had processor boards that filled the entire compartment and used Dallas chips. I always refitted those Dallas chips with sockets, but there is no shortcut to a data dump or full re-cal. The latest processor board (I have seen) uses a "coin" style battery. Loss of data or data dump during battery replacement can be a real problem. When dealing with stand along batteries I often "cheat" soldering in a couple temporary pins/eyelets to connect an external battery allowing me to remove the original battery without losing power/data during replacement. I then (if not already installed) add a battery socket with two permanent eyelets on +/- or the socket so replacement only takes a few minutes in the future.
Sadly this does not help with SnapHats and Dallas chips replacement. Although I wonder if a chip socket could be modified with +/- eyelet the stacks between the Snaphat battery and chip allowing easier future replacement.The point is I have so many pieces of equipment with critical data that I usually end up only replacing when the instrument dies. But once these up-grades are complete can save a lot of time allowing regular replacements. 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 Philipp Cochems via volt-nuts <[email protected]> Sent: Saturday, October 26, 2019 1:13 PM To: Discussion of precise voltage measurement <[email protected]> Cc: Philipp Cochems <[email protected]> Subject: Re: [volt-nuts] HP3458A - Black Edition Hi, one should always keep in mind that all the specifications are made to achieve a certain yield in production. Assuming a Gaussian distribution it is not very unlikely, that we all have 3458As which perform much better than specified. In that respect you cannot rely on vishay marketing. Reducing the LTZ1000 temperature is also not that easy. The 3458A might be a metrology grade DMM, but it is also a system DMM. Even on my bench the TEMP? sometimes goes up to 47°C (at 26°C room) and it might be even higher in the summer. And it is not in a rack and only a HP 3488A is sitting on top which produces almost no heat. Running the 3458A in a rack full of equipment will not allow to reduce the LTZ1000 that much. I think the gap to the Fluke 8588A is too wide to catch up with only a little bit improved specs. I think the main reason for the black edition is to ensure that many test rigs can work for the next years. Best regards Philipp Am Sa., 26. Okt. 2019 um 20:48 Uhr schrieb Frank Stellmach < [email protected]>: > @ 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. _______________________________________________ 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.
