@ 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
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