Hello, Dr. Frank!
I read much about HP 3458 in HP Journal. What about ADC they are different in hardware, however the algorithm is almost the same. And the ADC in HP 34401a I like a little more... I don't know why...
Excuse me, you mean that there aren't experts at Keysight to develop new DMM? Then how the're developing other instruments? Are they (the instruments) simpler than DMM?)))
HighVoltage, thank you very much for the picture! It's nice to meet them))
In a recent product presentation about the 34401As multislope III A/D, I remember to have read exactly that, i.e. simplified HW, same state machine principle like the 3458A. I don't find this presentation any more, maybe it is inside the old manuals.
Me and some of other volt-nuts in this forum followed closely the development, or better the changes due to bugs of the 3446x platform, especially the 465/470A ones. See former analysis of the 465A/470A in another thread. Therefore we came to know that several of the old 3458A designers were involved, and that they either retired, or went to Keithley.
The R&D story behind the 3458A BE is also known in parts.. why and how there was no deep redesign, and probably will not happen any more in the future.
The design of such an instrument (DMM) is also very complicated, mostly analogue magic, don't underestimate this, and do not compare that with those RF designs, which are a completely different kind of magic.
Good analogue designers are getting more and more rare, I fear.
RF designers will not necessarily have the wisdom to design good DMMs.
The most important business for KS are scopes, and so, especially margin-wise.
Just watch the current Keysight Live Lab, what products they promote the most.
Frank