A Josephson Junction is not a Cesium Standard. It is not quite to the Plug and Play level. And takes a few racks worth of space. Operation and Maintenance is more difficult then most calibrations. But big advances are being made. At some point in the not to distant future I foresee JJ arrays being configured as not just a references, but full function calibrators with direct quantum synthesis of any DC, AC, Ohms, and Current. Sam Benz has lead much of this research. http://www.nist.gov/pml/div686/devices/voltage.cfm I am amazed that greater advances have not been made in zeners references or more specifically their packaging
Thomas Knox > Date: Sat, 18 Jan 2014 17:44:43 -0700 > From: [email protected] > To: [email protected]; [email protected] > Subject: Re: [volt-nuts] What made a HP3458A so expensive > > Bill, > > Would a Josephson Junction standard need to be calibrated? > > Adjusted and maybe compared, yes, but you should not need to calibrate a > primary > standard? Years ago we had HP Cesium Frequency Standards at work. There were > primary standards and good to 4E-12 with no additional calibration. > > Joe > > > On 1/18/2014 3:37 PM, Tom Miller wrote: > > Can you imagine what it would cost to get that calibrated? > > > > Tom > > ----- Original Message ----- From: "Bill Gold" <[email protected]> > > To: "Discussion of precise voltage measurement" <[email protected]> > > Sent: Saturday, January 18, 2014 5:17 PM > > Subject: Re: [volt-nuts] What made a HP3458A so expensive > > > > > > In fact if you look at a 1982 HP catalog you will see that the 3456A was > > selling for around $3,700 and given inflation the 3458A is still a pretty > > good bargain when it was introduced in 1989. In 1989 the 3456A was selling > > for $4,600 while the 3458A was selling for $5,900. I wonder if there will > > > > ever be a "3459A" 9.5 digit meter? With a super miniture Josehpson Junction > > for a reference? > > Bill > > > > ----- Original Message ----- From: "Tom Knox" <[email protected]> > > To: "Discussion of precise voltage measurement" <[email protected]> > > Sent: Saturday, January 18, 2014 1:29 PM > > Subject: Re: [volt-nuts] What made a HP3458A so expensive > > > > > > Actually in spite of it's high price I feel the 3458A represents a bargain. > > When it was introduced in 1989 it was $5900. A price it held for decades. > > Although designed in > > then 80's it's accuracy is still unsurpassed. The 8846A is much less > > expensive because it has only about a quarter the parts. With few that > > are hand selected and/or aged. And all though both meter have well > > executed designs the result is the 3458A has about a magnitude greater > > accuracy. And anyone in Metrology can attest to the fact that the cost > > of accuracy is exponential. But the thought I wanted to contribute to the > > dialog is the real value of the 3458A is the body > > of knowledge built around the thousands of 358A's some running > > continuously for nearly three decades. The characteristics of the 3458A > > are perhaps the best documented of any electronic instrument ever made. > > That is priceless. When comparing that body of knowledge to individual > > units I have found every 3458A is a little different and seem to each > > have their own personality. In a side note, recently I owned what appeared > > > > to be the original 3458A. I cannot remember the serial number, but it had > > the numbered stickers identifying the boards that can be seen in the > > original service manual. And it was still working flawlessly. > > > > Thomas Knox > > > > > > > >> Date: Sat, 18 Jan 2014 17:41:26 +0100 > >> From: [email protected] > >> To: [email protected] > >> Subject: [volt-nuts] What made a HP3458A so expensive > >> > >> Well, > >> > >> the 3458A now is in production for about 25 years , and only around 50k > >> units have been sold. > >> (That's an estimation by Joe Gellers series number collection) > >> > >> As the 3458A is a niche product with homeopathic series volume, the > >> development, verification/validation, special reliability engineering, > >> selection and burn-in measures, QA costs had to be paid per unit in the > >> beginning. > >> > >> To my opinion, especially the 3458A was designed mainly for military > >> requirements (Tamb 55°C). The military was willing to pay a premium (HP > >> = High Price) at that time. So HP was able to realize that price. > >> > >> All that development budget is long paid, and after end of the Cold War, > > > >> the military does not order so many devices anymore, what caused the > >> problems of the T&M business (finally => Keysight, urgh!). > >> > >> But as that market is tight, competitors are few, so the price is not > >> going down, instead it's increasing over the years, from $5900 to around > > > >> $8500. > >> > >> It would be interesting to calcualte the BOM of the 3458A. > >> As they use many custom specific components, it should be relatively > >> expensive. > >> > >> > >> > >> There is no parameter in the HP3458A specifications, that the device has > > > >> to be powered constantly to meet the specs. > >> Those very high 8ppm/yr. drift might apply only during continuous > >> operation. > >> During power down, the LTZ should not drift at all, as the ageing > >> mechanism is driven by temperature. > >> But there might be (there are indeed) considerable hysteresis effects. > >> > >> I have set the temperature of my HP3458A to ~ 60°C, I shut it down after > >> usage, and the periodical comparison to 3 other references shows a drift > > > >> of less than 1ppm/year. > >> > >> Frank > >> > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
