> > 2014-08-12 1:25 UTC+03.00, Tom Knox <actast@hotmail.com>: >> I am not sure the use of LM329's was a cost saving measure or >> compromise, actually the 4410 uses a different approch, it's basicly >> is a big oven. Guildline has been a Metrology leader for decades and >> has been a leader including temp measurements and oil baths so I >> for one would be interested in how well their approach to a voltage >> standard performs. > > The 4410 was not designed or manufactured by Guildline. Just like many > of the products sold under their brand name. > > At the time of design the LTZ1000 was not yet available and the Fluke > ref amp was obviously property of Fluke only. The only same level > technology available to all manufactueres was the 1N829 zener which if > carefully selected and matched can be as good as LTZ1000. Datron > calibrators with multiple selected, aged and matched 1N829 zeners are > a good example of that. > > The original 100 page (Statronics) documentation seems to be a masters > thesis rather than a product manual and has a detailed description of > the design process. The text mentions that the 1N829 temperature > compensated zeners were discarded because of the poor availability in > Australia where the unit was developed. The LM399/LM329 series was > selected because it was the "best available". Band-gap type references > were also evaluated but found unsatisfactory at the early stage. Will, Is that (Statronics) documentation available anywhere on the net for download? I'd be interested in reading about the technology behind the design, since I have built my own shop standard using four LM399 heated zeners. Thanks for the info, Dave M