Re: [volt-nuts] HP-3458A Zero Reading
On 7/27/2015 10:26 PM, Mike S wrote: On 7/27/2015 7:54 PM, Bill Gold wrote: You will observe that the HP/Agilent/Keysight manual for the 3458A does not give any zero stability specs, at least that I can find. On DC 100 mV range, the standard model is spec'd for 14+3 ppm of range @ 2 years from calibration, not considering temperature. That's 1.7 uV, from my reckoning. The OP's reading of 0.7 uV is well within that - it even beats the 90 day spec. Doh. That 14+3 actually equates to ~=3 ppm ~= 0.3 uV (since reading is essentially zero), but there's also temperature, which contributes 0.115 / C. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] plastic caps on 3458A reference board
On 1/28/2015 9:00 AM, J. L. Trantham wrote: In the days of 3D printers and CAD/CAM, it might be possible to have a 'run' of these 'made to order', so to speak. I'd think a couple of pieces of pink (non-conductive) closed cell antistatic foam, one hollowed out a bit with a penknife, would work well. It would both shield from airflow and provide insulation. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Old HP3458A - SN: 2823A 03939
On 10/8/2014 4:23 AM, acb...@gmx.de wrote: the EPROMs are in sockets, no soldering needed. but again, buying a precision instrument but reprogramming cal data that is years old does not make any sense. unless of course if you are just a collector and do not use its accuracy. It makes perfect sense, for the same reason that HP doesn't touch the cal if it's in spec - for tracking/characterization. By keeping the same cal constants, if and when he does send it in for calibration he'll be able to know how much it drifted since it was last cal'd (25 years ago?). -- Mike ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] LM399 Long term drift specification
On 9/10/2014 7:00 PM, Tony wrote: I've just noticed that TI and Linear's specs for 'Long Term Stability' (typical) are different. TI state 20ppm/1000Hr while Linear state 8ppm/SQRT(kHr). That's a big difference - is this likely to be a real difference or just specmanship? I note that Linear (in Note 4) also state that Devices with maximum guaranteed long-term stability of 20ppm/SQRT(kH) are available. Presumably they would be a special order as there doesn't appear to be a unique part no. Would they be likely to be much more expensive? Isn't 8ppm/SQRT(kHr) better than 20ppm/SQRT(kH)? Why would the latter be more expensive? Or is it the difference between typical and guaranteed? -- Mike ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 5200A extender board.
On 8/29/2014 2:16 PM, Tom Miller wrote: Did you remove the two holes? :) You mean the two pin 1 markers on the silkscreen? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
On 8/25/2014 11:02 AM, Don@True-Cal wrote: Silver or Gold plating on the terminal or wire will introduce the undesirable dissimilar metal properties, both at the plating junction and at the plating metal to DUT terminal. Why? Any Seebeck effect is immediately offset in the opposite direction, since both junctions are (under normal conditions) at essentially the same temperature (e.g. there's a copper-gold thermocouple, the minimal thermal resistance of a micron of gold on the contact(s), then a gold-copper thermocouple). It seems to me that the improved consistency of the contact outweighs any loss from the thermocouples. A more typical contact would be copper-nickel plate-gold plate, but the concept is the same. Unless there is heat flowing through the entire assembly so one thermocouple is warmer than the offsetting one (e.g. shortly after plugging in a banana plug warmed by body heat), they simply cancel. Even if connecting gold plated to nickel plated contacts, it works out the same - a copper-nickel-gold-nickel-copper connection is completely offset. It's when the offsetting thermocouples occur across a temperature gradient that you have problems. -- Mike ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Question for Fluke 732A owners
On 2/26/2014 6:53 PM, J. L. Trantham wrote: Oh!! THAT's what they mean by 'male' and 'female'. I get it! :^)) You jest, but it's not always clear. Take the common Cannon D-sub connectors. A connector with male contacts will have have a female shield, making gender ambiguous. That's why they come in P (pin) or S (socket) forms, and not male/female. Or the old Token Ring connectors (or even older GR-874), which were hermaphroditic. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3457A
On 8/12/2013 2:23 PM, John Phillips wrote: A calibration indicates that the unit under test is withing manufactures specification. The equipment and procedure used has to be good enough (bad words in a cal lab) to have a high probability (nothing is 100%) of insuring the calibration documentation is valid. Things can can be a little looser if you are calibrating a 1% meter with a 10 ppm meter but it does not work the other way around. You can calibrate either way. You can't however, calibrate the 10 ppm meter so it's in spec using a 1% meter. That's different. Calibration merely means that it's documented how close it is to a reference, such as NIST, not that it's within the manufacturer's spec. The 10 ppm meter would end up with a 1%+ calibration - precise but not accurate. Not particularly useful, but valid. A good cal lab would do a calibration to specification, where the uncertainties place the 10 ppm meter within spec. As I cited and someone else already quoted, calibration is the property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. Nothing to do with making a device meet its specifications. That's why an eBay seller can claim they'll do a calibration traceable to NIST, because they're not claiming any particular accuracy. It's really not worth anything, unless they give specific uncertainties or claim calibration to manufacturer's specification. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
