As far as I know, the 3458A was bought by the thousands by defense and space organizations. I'd guess no-one else would support that kind of development. Well maybe the telecom sector if there was a need for such an instrument. > > No one else ever will. *WAY* too expensive for even Keysight to redesign these days. Just is not going to happen... > > Could you say a bit more about this? Did the 3458A not make economic sense for HP at the time? Is nobody buying 8.5s these days? The reason I ask is that I think we all have the general sense that as technology advances, getting to any particular design objective gets slowing easier as the years roll on. This would be an interesting data point to illustrate why that isn't always so. Possible to say more? > > Alan

-------- In message <CAFoWNwCWaz3F931THBhX+E2OTVT+HBPQ3RxTd+GOmm9uibsKNw@mail.gmail.com> , Jan Fredriksson writes: >> Could you say a bit more about this? Did the 3458A not make >>economic sense for HP at the time? Is nobody buying 8.5s these days? It's an interesting historical confluence: 8.5's are the clippers of DVMs. 8.5 only makes sense two places: fundamental/high-end metrology and basic research. Everybody else are totally fine with 7.5 and very few actually need more than 6.5 (specifying the temperature of your aligator-clips gets old really fast.) The 3458A made it possible to validate the josephson junction as SI voltage reference -- which ironically made the 3458A surplus to metrology requirements: Now you can generate any voltage you want on demand. That leaves a theoretical market in basic research, but that's a very small market which will happily pay a phd-theses for a prototype, but unless its on CERN scale, production runs are never an option. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.