Bill, I agree with the comments made by you and everyone else. That's why I said "..if it's good enough..". But there's one thing that kind of slid by everyone. All the other suggestions conclude with some variation of "..needs to be calibrated..". Is there any other way to get a NIST-traceable voltage into your shop for $35? (I'm not challenging you, I'd really like to know if there is another alternative) Granted, it's only at the 10 uv level, but for many applications that *is* good enough.
Let's be honest, as time-nuts we're spoiled rotten. Almost all of us have got rubidium standards at 10E-11 per day or better and at a ridiculously low price. Many have got cesium standards and a few have got hydrogen masers. We can calibrate them against GPS or Loran-C to obsessive-compulsive levels. So far, none of the other physical standards allow that level of independence for hobbyists. So when dealing with other measurement units (e.g. volts, ohms, etc) we either have to ease the requirements by orders of magnitude or increase the budget by orders of magnitude! If you're doing this as part of your job and can justify the need and the expense - great! I'm a hobbyist and I won't be spending $1843 any time soon to have NIST calibrate a DC solid-state voltage reference. For my needs Geller Labs provides good value for the very nominal cost. And just to be clear, I have no relationship with Geller Labs. Ed WB6BNQ wrote: > No way in hell does that thing qualify as a voltage standard. It barely > qualifies as a VERY short term transfer device assuming the temperature does > not change. > > If you want a real voltage reference then buy, from eBay, a Fluke 731B > voltage standard. You will still need to get it calibrated, but then it will > hold under 10ppm for well over a year or > more. Actually, if they are adjusted correctly, you can get less than 5ppm > and it will hold it at a given temperature. These items are serious devices > and their latest versions (very expensive) > are better than a properly maintained and operated group of standard cells. > > I completely disagree with Brian about buying any standard cells. Whatever > voltage value they had is lost upon shipment. Shaking the cells changes the > value and it will not return to the > original value. If you did have a set of cells, you would want at least 4 of > them. Then study statistical math all over again because you will need it to > use the cells. > > As Brian does suggest, you would be much better off picking up a hp3456A, > 3457A, 3458A or getting one of Fluke 8500 series if it has the Ohms and AC > options included. The basic Fluke 8500 series > is DC only mainframe. > > Measuring your resistors, using one of the above DVMs, in the 4-wire mode is > about the best you could possibly do. To do any better would require some > very serious effort. > > By the way you could buy several of the latest and greatest Fluke super DVMs > for the cost of what it would take to do a Josephson array and still have > money left over to fund that divorce. > > Bill....WB6BNQ > > > Ed Palmer wrote: > > >> It's nowhere near the idea of a Josephson array, but if a NIST-traceable 10V >> +-10uV reference is good enough to satisfy your voltage-nut urges, you can >> buy it from www.gellerlabs.com for $35. >> >> I also have a few standard resistors (e.g. 1.000002 ohms) that I'd be >> interested in calibrating, but I can't seem to come up with a practical way >> of doing it. >> >> Frustrating, isn't it? :-) >> >> Ed >> _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
