From jra at febo.com Sat Aug 1 23:23:15 2009 From: jra at febo.com (John Ackermann) Date: Sat, 01 Aug 2009 19:23:15 -0400 Subject: [volt-nuts] Administrivia: febo.com SSL certificates Message-ID: <4A74CE63.9080303@febo.com> Since some of you will be going to the secure version of febo.com to sign up for volt-nuts or to otherwise mess with your time-nuts subscription, just a reminder that I use a self-signed SSL certificate rather than spending $$$ each year to buy a cert from someone. So, if you are warned about an invalid certificate when you go to https://www.febo.com, you can safely accept it; the error is just due to the lack of commercial signing. John From phill.r1 at btinternet.com Sun Aug 2 15:42:35 2009 From: phill.r1 at btinternet.com (Roy Phillips) Date: Sun, 2 Aug 2009 16:42:35 +0100 Subject: [volt-nuts] Quality Multimeters Message-ID: <2B0CDD49C9E548558C511032F1F4BFD2@LapTop> Hello to all the members There has been considerable discussion on the time-nuts site regarding the HP3458, which I would like to add to my other HP DVM's. This is a problem due to the relative rarity, and therefore cost in the UK. But I have got a 3457 and a 3456 in my lab. What is the general opinion of the 3457 - is it a good deal short of the 3458 - I gather it is all down to the voltage reference device. It would seem that obtaining a good DC voltage standard (mine is a Fluke 731B), is much more difficult than the frequency standard, with a heap of GPS and other gear at inexpensive price levels. Any good designs for this purpose, or is it best to find commercial products. Any advice on these matters would be welcome. Roy From kilodelta4foxmike at gmail.com Sun Aug 2 18:32:43 2009 From: kilodelta4foxmike at gmail.com (Brian Kirby) Date: Sun, 02 Aug 2009 13:32:43 -0500 Subject: [volt-nuts] Quality Multimeters In-Reply-To: <2B0CDD49C9E548558C511032F1F4BFD2@LapTop> References: <2B0CDD49C9E548558C511032F1F4BFD2@LapTop> Message-ID: <4A75DBCB.7040306@gmail.com> Roy Phillips wrote: > Hello to all the members > > There has been considerable discussion on the time-nuts site regarding the HP3458, which I would like to add to my other HP DVM's. This is a problem due to the relative rarity, and therefore cost in the UK. But I have got a 3457 and a 3456 in my lab. > What is the general opinion of the 3457 - is it a good deal short of the 3458 - I gather it is all down to the voltage reference device. > It would seem that obtaining a good DC voltage standard (mine is a Fluke 731B), is much more difficult than the frequency standard, with a heap of GPS and other gear at inexpensive price levels. Any good designs for this purpose, or is it best to find commercial products. > Any advice on these matters would be welcome. > Roy > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > Its up to the references and the A/D converters have to be very linear. I recently had my cal lab to do a test on the 3457A (7-7-2009). I had them to hook it up to their calibrator system, A Fluke 5700A, which they rated at 1.0000000V at 8 ppm and I had them to let the meter average the measurement for 10 minutes. The mean reading was 1.000002V and the STD Dev was 137.3x10-9. I also had them to read 10V, using their Fluke 732B which was certified at 9.999959V at +/- 0.4 ppm. The instrument read 9.999956, the STD Dev was 5.358x10-6 for ten minutes. I read somewhere that HP rates the instrument at 5 ppm, and from the 10V readings that appears to be very close. The 3456A is rated 2 ppm, but you can only read 6 digits. Brian - KD4FM From drfrank.stellmach at freenet.de Sun Aug 2 19:50:40 2009 From: drfrank.stellmach at freenet.de (Dr. Frank Stellmach) Date: Sun, 02 Aug 2009 21:50:40 +0200 Subject: [volt-nuts] Quality Multimeters: HP 3457A Message-ID: <4A75EE10.9020009@freenet.de> Hello Roy, take into account the 34401A also, as the spec (stability) are very similar to the 3457A. The 3457A has some extended DCI ranges, compared to the 34401, but also no complete ACAL feature, as the 3458A. I have in mind, that the 3457A may also be used in 7 1/2 digit mode, but could not find this in the manual. The 34401A can deliver more digits than 6 1/2 via GPIB Linearity is 2ppm, but the 3457A is not specified at all in this regard. Seems to me, that the 3457A is an elderly design, discretely built, and has not been so common. The 34401A design is derived from the 3458A, more compact and ruggedized. Anyhow, better go for the 3458A. ACAL, its stability and precision, the complete set of current ranges, the different possibilities to make high precision AC measurements, and the digitizing fetures are all worth the money. I was lucky to pick a 9 year old unit here in Germany for about 3000? recently. I built a LTZ1000A based, dual reference, as a replacement of Fluke 732A / 732B or 7001. Short term stability (1h) compared with the 3458A is around 2e-7. Then I added a one decade precision divider for linearity testing (like a 720A), and a 10:1, 100:1 reference divider, like the 752A. Mentioned commercial devices are also rare here, but if you find them, they are too expensive in most cases here in EU. I think, the US market would be a better place to acquire them, despite tax & toll. The analogous device to the time-nuts cesium clock would be a Josephson array plus HF-devices plus liquid helium. It's a pity that "volt" cannot be transferred wireless also.. Frank Stellmach From gbusg at comcast.net Sun Aug 2 23:27:57 2009 From: gbusg at comcast.net (Greg Burnett) Date: Sun, 2 Aug 2009 17:27:57 -0600 Subject: [volt-nuts] ...a guide to buying the HP/Agilent 3458A References: <2B0CDD49C9E548558C511032F1F4BFD2@LapTop> Message-ID: <006e01ca13c8$de99f8a0$6501a8c0@gb02> Danger Signs: ========== 1. The seller states it as "untested" and/or claims not to have even bothered to power it up and run self-test. ...Note that many such boxes have hardware failures. Your original acquisition cost + repair can easily exceed cost of buying a fully tested unit. 2. The seller's photo shows it as powered up but you can see "Err" in small letters below the main characters in the display. ... "Err" means an error was reported and the seller would need to hit "Blue Shift" Error to find out which error(s). Watch out for the Version of its A5 Outguard Controller: ====================================== 1. Old version is 03458-66505 (first released in 1988) or 03458-66515 if opt. 001 It has 3 SRAMs, each having a non-replaceable internal battery that lasts 10 to 15 years. When the batteries crash, you'll loose your cal constants and your DMM won't work. The fix is to either replace the 3 SRAMS (expensive) or upgrade to the new ver. A5 The SRAMS are qty 2 DS1230Y and qty 1 DS1220Y. Check the datecodes on them. Bottom line: If date codes are more than 10 years ago, you're living on borrowed time! Firmware might be very old. ...depends on age but might be between ver. 2 to ver. 8. 2. New version is 03458-66547 or 03458-66548 if opt. 001 Much better! Uses new version Non-volatile RAM with user replaceable batteries! Has much newer version firmware. (Probably ver. 8 or later.) Cheers, Greg From holrum at hotmail.com Mon Aug 3 04:12:40 2009 From: holrum at hotmail.com (Mark Sims) Date: Mon, 3 Aug 2009 04:12:40 +0000 Subject: [volt-nuts] ...a guide to buying the HP/Agilent 3458A In-Reply-To: References: Message-ID: Although the life of these chips is spec'd at 10 years, their probable life at normal storage/operating temperature is probably 30+ years. I talked to a designer of these devices and he said the limiting factor in most cases is the self-discharge rate of the internal batteries. The actual lifetime is determined by statistical luck of the draw. If the batteries go, you will need to replace the chips and do a full cal. If your chips are old and you are having a full cal done, it would be best to replace them. A full cal will set you back around $500. The chips should be around $50... cheap insurance. I have some Tek 1503B/C TDR's that are over 20 years old. The Dallas Semi batteries have never been changed and still measure 3.6V. ---------------------------------------- _________________________________________________________________ Windows Live?: Keep your life in sync. http://windowslive.com/explore?ocid=PID23384::T:WLMTAGL:ON:WL:en-US:NF_BR_sync:082009 From gbusg at comcast.net Mon Aug 3 05:18:45 2009 From: gbusg at comcast.net (Greg Burnett) Date: Sun, 2 Aug 2009 23:18:45 -0600 Subject: [volt-nuts] ...a guide to buying the HP/Agilent 3458A References: Message-ID: <00c401ca13f9$e085a5c0$6501a8c0@gb02> Mark - a few questions that might be helpful to the rest of us... 1. How do we measure the internal battery voltage for the DS1230Y and DS1220Y chips? ...Across which pin numbers? 2. Where can we buy the 3 chips for around $50? (That sounds like a good deal to me.) BTW, my first 3458A NVRAM battery failure occurred at 15 years, right in the middle of a critical 6 month-long data collection experiment. So this was catastrophic. In a second 3458A, the NVRAM battery failure occurred at 16 years. Over their lifetimes, I estimate those two units were powered up only 10 percent of the total time. So if someone powers-up their 3458A more of the time (e.g. running 24/7 all those years), maybe they stand a better chance of longer battery life? (These chips automatically disconnect their internal batteries when Vcc rises above 3Vdc.) The 3458A first went into production 21 years ago. Time sure flies when we're having fun! -Greg From df6jb at ulrich-bangert.de Mon Aug 3 05:26:34 2009 From: df6jb at ulrich-bangert.de (Ulrich Bangert) Date: Mon, 3 Aug 2009 07:26:34 +0200 Subject: [volt-nuts] Quality Multimeters: HP 3457A In-Reply-To: <4A75EE10.9020009@freenet.de> Message-ID: <290E7076273247ADA22CEACE2BD11CBF@athlon> Gentlemen, > I have in mind, that the 3457A may also be used in 7 1/2 > digit mode, but > could not find this in the manual. The 3457A has an additional "high resolution register" that may be read completely apart the normal measured result over GPIB and added to the measured result for appr. 7 1/2 digit resolution. I have used this feature with a PT100 4-wire measurement to give me a 1/100 degree C resolution for a thermometer. BTW: The 3457A is one of the devices that does not make use of the GPIB EOI-line (unless explicitely told so). Unless you are aware of that getting GPIB communication to work can be a real pain. Best regards Ulrich Bangert > -----Urspr?ngliche Nachricht----- > Von: volt-nuts-bounces at febo.com > [mailto:volt-nuts-bounces at febo.com] Im Auftrag von Dr. Frank Stellmach > Gesendet: Sonntag, 2. August 2009 21:51 > An: volt-nuts at febo.com > Betreff: [volt-nuts] Quality Multimeters: HP 3457A > > > Hello Roy, > > take into account the 34401A also, as the spec (stability) are very > similar to the 3457A. > The 3457A has some extended DCI ranges, compared to the > 34401, but also > no complete ACAL feature, as the 3458A. > > I have in mind, that the 3457A may also be used in 7 1/2 > digit mode, but > could not find this in the manual. > The 34401A can deliver more digits than 6 1/2 via GPIB > Linearity is 2ppm, but the 3457A is not specified at all in > this regard. > > Seems to me, that the 3457A is an elderly design, discretely > built, and > has not been so common. > > The 34401A design is derived from the 3458A, more compact and > ruggedized. > > > Anyhow, better go for the 3458A. > ACAL, its stability and precision, the complete set of > current ranges, > the different possibilities to make high precision AC > measurements, and > the digitizing fetures are all worth the money. > > I was lucky to pick a 9 year old unit here in Germany for about 3000? > recently. > > I built a LTZ1000A based, dual reference, as a replacement of > Fluke 732A > / 732B or 7001. > Short term stability (1h) compared with the 3458A is around 2e-7. > > Then I added a one decade precision divider for linearity > testing (like > a 720A), and a 10:1, 100:1 reference divider, like the 752A. > > Mentioned commercial devices are also rare here, but if you > find them, > they are too expensive in most cases here in EU. I think, the > US market > would be a better place to acquire them, despite tax & toll. > > > The analogous device to the time-nuts cesium clock would be a > Josephson > array plus HF-devices plus liquid helium. It's a pity that > "volt" cannot > be transferred wireless also.. > > Frank Stellmach > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. From phk at phk.freebsd.dk Mon Aug 3 07:45:22 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Mon, 03 Aug 2009 07:45:22 +0000 Subject: [volt-nuts] ...a guide to buying the HP/Agilent 3458A In-Reply-To: Your message of "Mon, 03 Aug 2009 04:12:40 GMT." Message-ID: <71589.1249285522@critter.freebsd.dk> In message , Mark Sims writes: >If the batteries go, you will need to replace the chips and do a full cal. > If your chips are old and you are having a full cal done, it would be be >st to replace them. A full cal will set you back around $500. The chips s >hould be around $50... cheap insurance. ...or provide them with an external backup-supply higher than 3.0 and lower than 4.5 Volts. At 4.5 Volts the chips go into Read-Only mode and the internal backup battery is a 3V lithium. I have not tried this on the 3458A yet, but I have used this trick in other kit. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From phill.r1 at btinternet.com Mon Aug 3 09:32:47 2009 From: phill.r1 at btinternet.com (Roy Phillips) Date: Mon, 3 Aug 2009 10:32:47 +0100 Subject: [volt-nuts] Quality Multimeters: HP 3457A In-Reply-To: <4A75EE10.9020009@freenet.de> References: <4A75EE10.9020009@freenet.de> Message-ID: <90F51C891B6C45E5BAC045E908B94F21@LapTop> Hello Frank Thanks for you assessment of the "quality" DVM's - - I also have a 34401A, but I have never been confident that it was in the "quality" league. This is probably because of the opinion of a dealer, who considered it to be inferior, and perhaps the fact that it has been discontinued, although this latter factor is probably more to do with marketing. But I had not realized that its design was based upon the 3458A, I will now consider having it checked for calibration. A considerable number of 3457A's have been available in the UK, as I gather that it was widely used as a system DMM by the various military organizations - but you are right - it is aging now, despite the fact that it uses two processors ! I will continue with the quest for a 3458A. Thanks for your suggestions regarding the "home made" voltage standard - I have seen the LTZ1000A mentioned on many occasions. ----- Original Message ----- From: "Dr. Frank Stellmach" To: Sent: Sunday, August 02, 2009 8:50 PM Subject: [volt-nuts] Quality Multimeters: HP 3457A Hello Roy, take into account the 34401A also, as the spec (stability) are very similar to the 3457A. The 3457A has some extended DCI ranges, compared to the 34401, but also no complete ACAL feature, as the 3458A. I have in mind, that the 3457A may also be used in 7 1/2 digit mode, but could not find this in the manual. The 34401A can deliver more digits than 6 1/2 via GPIB Linearity is 2ppm, but the 3457A is not specified at all in this regard. Seems to me, that the 3457A is an elderly design, discretely built, and has not been so common. The 34401A design is derived from the 3458A, more compact and ruggedized. Anyhow, better go for the 3458A. ACAL, its stability and precision, the complete set of current ranges, the different possibilities to make high precision AC measurements, and the digitizing fetures are all worth the money. I was lucky to pick a 9 year old unit here in Germany for about 3000? recently. I built a LTZ1000A based, dual reference, as a replacement of Fluke 732A / 732B or 7001. Short term stability (1h) compared with the 3458A is around 2e-7. Then I added a one decade precision divider for linearity testing (like a 720A), and a 10:1, 100:1 reference divider, like the 752A. Mentioned commercial devices are also rare here, but if you find them, they are too expensive in most cases here in EU. I think, the US market would be a better place to acquire them, despite tax & toll. The analogous device to the time-nuts cesium clock would be a Josephson array plus HF-devices plus liquid helium. It's a pity that "volt" cannot be transferred wireless also.. Frank Stellmach _______________________________________________ volt-nuts mailing list -- volt-nuts at febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. From phk at phk.freebsd.dk Mon Aug 3 10:30:03 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Mon, 03 Aug 2009 10:30:03 +0000 Subject: [volt-nuts] Quality Multimeters: HP 3457A In-Reply-To: Your message of "Mon, 03 Aug 2009 10:32:47 +0100." <90F51C891B6C45E5BAC045E908B94F21@LapTop> Message-ID: <72170.1249295403@critter.freebsd.dk> In message <90F51C891B6C45E5BAC045E908B94F21 at LapTop>, "Roy Phillips" writes: >Thanks for you assessment of the "quality" DVM's - - I also have a 34401A, >but I have never been confident that it was in the "quality" league. The only blemish on the 34401A is measuring very low AC voltages/currents, where some serious unlinearity shows up. See: http://www.gellerlabs.com/34401A%20Low%20Level%20AC%20Voltage.pdf -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From gbusg at comcast.net Mon Aug 3 11:07:17 2009 From: gbusg at comcast.net (Greg Burnett) Date: Mon, 3 Aug 2009 05:07:17 -0600 Subject: [volt-nuts] Quality Multimeters References: <2B0CDD49C9E548558C511032F1F4BFD2@LapTop> Message-ID: <000f01ca142a$90eca410$6501a8c0@gb02> IMO the 3457A, 3456A and 34401A are all excellent DVMs. All three DVMs must be adjusted at many cardinal points for DCV, ACV and Ohms. Of course these adjustments are via physical pots in the 3456A, whereas most are via electronic cal constants in the 3457A and 34401A. I would say that the 3457A is a little bit the predecessor of the thinking that went into the development of the 3458A. But the 3458A is still king by a thousand miles. Nothing else comes close. Its internal "ACAL" routines take advantage of the 0.02ppm linearity of its DAC, establishing ratios from one range to the next (and from its LTZ1000A zener reference voltage to full-scale on its 10V range). Consequently its adjustments to the external world require only a short, a 10Vdc standard and a 10k ohm resistor. It even adjusts its own AC freq. response (during ACAL AC) by adjusting for the most pure flat top of an internally generated square wave. Its most accurate AC mode (AC SYNC) digitizes AC sinewaves and then calculates and displays their voltage. After a 3458A has been adjusted at "0", 10Vdc and 10k ohms (and SCAL AC if needed for AC HF frequency response above 2MHz) - and after internal ACAL - it will meet all published specs. (Or else it's broke and needs repair because there's nothing else to adjust.) It's had an amazing long life (21 years) so far. Cheers, Greg From holrum at hotmail.com Mon Aug 3 15:15:04 2009 From: holrum at hotmail.com (Mark Sims) Date: Mon, 3 Aug 2009 15:15:04 +0000 Subject: [volt-nuts] ...a guide to buying the HP/Agilent 3458A In-Reply-To: References: Message-ID: You should pay around $20 each for the DS1230 and $10 for the DS1220. I bought mine from a local dealer. Digikey also has them. If you buy 24-36 of them the price drops to around $13/$7. I don't think the internal voltage is available on those chips. The Tek 1503B uses a DS memory keeper battery and external SRAMs. The battery/power controller are the same as in the DS RAM chips. For the 2Kx8 device you could probably substitute a ferroelectric SRAM... no batteries needed. Somewhere there is a place that sells a small PCB with an FRAM on it to substitute for the DS1220 in some arcade games. It should not be hard to build a DS1230 replacement. I have also seen some small PCB's outfitted with a SMT 32kx8 ram and external battery that substitute for the DS1230 chips. The batteries on these were much less capacity than the internal DS1230 battery, but was changeable. I do a lot of work on Tek TM500 series modules. The DM5010 meter saves its cal constants in a RAM backed up by a 2 cell rechargeable NiCad (remember to use that meter occasionally or you will need to recal). If one cell goes bad, the RAM contents usually survive. I built a device out of a battery and DIP clip that allows one to hot-swap the (soldered down) nicad battery without losing the memory. I usually replace the NiCad with a lithium battery/series diode so you don't have to worry about keeping the thing charged. ---------------------------------------- _________________________________________________________________ Get back to school stuff for them and cashback for you. http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHYCB_BackToSchool_Cashback_BTSCashback_1x1 From slburris at gmail.com Mon Aug 3 15:34:32 2009 From: slburris at gmail.com (Scott Burris) Date: Mon, 03 Aug 2009 08:34:32 -0700 Subject: [volt-nuts] any gotchas for these Fluke voltmeters? Message-ID: <4A770388.6010509@gmail.com> After reading about the tribulations of battery backed SRAM failing on HP voltmeters, I was starting to wonder if there are any common service issues with the Fluke voltmeters I have. I have 3 Flukes: 8502A 8505A 8860A Any horrible time bombs lurking in these? Or service or operational issues others have run into? Thanks! Scott From holrum at hotmail.com Mon Aug 3 15:41:03 2009 From: holrum at hotmail.com (Mark Sims) Date: Mon, 3 Aug 2009 15:41:03 +0000 Subject: [volt-nuts] HP3457 quirks and gripes In-Reply-To: References: Message-ID: My main gripe with the 3457A is that high-res mode. It was just plain stupid on HP's part to not make the meter operate directly in 7.5 digit mode. Why does one have to read a separate register and manually add it to the reading? Come now... can't a microprocessor do that better than a person. In fact I built a 3457A GPIB interface to a MegaDonkey touch screen LCD controller specifically to read the high res register and do the addition/display. Another thing to watch out for on the 3457A is the "seams" between the ranges. Even on units freshly checked out and calibrated from HP I have seen rather large errors in readings when I put a precision resistance decade box or voltage cal source on the thing. Stepping the value from say 2.9V to 3V and from 3.1V to 3V produces different readings that were out of spec. (the 3V point seems the most error prone). ---------------------------------------- _________________________________________________________________ Get back to school stuff for them and cashback for you. http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHYCB_BackToSchool_Cashback_BTSCashback_1x1 From kilodelta4foxmike at gmail.com Tue Aug 4 00:52:46 2009 From: kilodelta4foxmike at gmail.com (Brian Kirby) Date: Mon, 03 Aug 2009 19:52:46 -0500 Subject: [volt-nuts] HP3457 quirks and gripes In-Reply-To: References: Message-ID: <4A77865E.4000909@gmail.com> We'll, asking the 3457A to read 7.5 digits - exceeds the capability of the internal reference. A 6.5 digit meter needs a reference to have 0.5 ppm stability. The service manual rates the instrument at 5 PPM, and when I had a cal lab to test my unit, it came back as 5.8 ppm. Something else to remember, is the last digit of the multimeter should not really be used, if your concerned about accuracy. A good application note to read on this issue is AN82-1 from Linear Technology. There is a graph on the front page that sums it up. Mark Sims wrote: > My main gripe with the 3457A is that high-res mode. It was just plain stupid on HP's part to not make the meter operate directly in 7.5 digit mode. Why does one have to read a separate register and manually add it to the reading? Come now... can't a microprocessor do that better than a person. In fact I built a 3457A GPIB interface to a MegaDonkey touch screen LCD controller specifically to read the high res register and do the addition/display. > > Another thing to watch out for on the 3457A is the "seams" between the ranges. Even on units freshly checked out and calibrated from HP I have seen rather large errors in readings when I put a precision resistance decade box or voltage cal source on the thing. Stepping the value from say 2.9V to 3V and from 3.1V to 3V produces different readings that were out of spec. (the 3V point seems the most error prone). > > ---------------------------------------- > > > _________________________________________________________________ > Get back to school stuff for them and cashback for you. > http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHYCB_BackToSchool_Cashback_BTSCashback_1x1 > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > From holrum at hotmail.com Tue Aug 4 01:00:14 2009 From: holrum at hotmail.com (Mark Sims) Date: Tue, 4 Aug 2009 01:00:14 +0000 Subject: [volt-nuts] HP3457 quirks and gripes In-Reply-To: References: Message-ID: Well, actually the last digit in ANY instrument is just marketing department eyewash... but can be useful for getting a feel for the trend of the measurements. As far a 6.5 digit meters needing a .5 ppm reference... that is for absolute accuracy, not measurement resolution. Look at the 3458 specs... 8.5 digit meter, 2 ppm ref at best. Absolute accuracy is in the 6 digit range... and it is the best meter on the market (and has been for the last 20 years). ---------------------------------------- _________________________________________________________________ Get your vacation photos on your phone! http://windowsliveformobile.com/en-us/photos/default.aspx?&OCID=0809TL-HM From gbusg at comcast.net Tue Aug 4 01:50:58 2009 From: gbusg at comcast.net (Greg Burnett) Date: Mon, 3 Aug 2009 19:50:58 -0600 Subject: [volt-nuts] HP3457 quirks and gripes References: Message-ID: <00c001ca14a6$03c836e0$6501a8c0@gb02> Mark wrote: Well, actually the last digit in ANY instrument is just marketing department eyewash... but can be useful for getting a feel for the trend of the measurements. As far a 6.5 digit meters needing a .5 ppm reference... that is for absolute accuracy, not measurement resolution. Look at the 3458 specs... 8.5 digit meter, 2 ppm ref at best. Absolute accuracy is in the 6 digit range... and it is the best meter on the market (and has been for the last 20 years). -------clip-------- The LSD resolution is useful *if* the meter's short-term noise and drift are low enough. For example the 3458A's 10 minute spec on 10Vdc range is 0.05ppm of reading + 0.05ppm of range. On the same range its 24 hour spec is 0.5ppm of reading + 0.05ppm of range. The 3455A is an example of the opposite situation (in which its selectable ppm LSD is pretty much meaningless because it's short-term noise and drift are too high). Greg From drfrank.stellmach at freenet.de Tue Aug 4 17:01:16 2009 From: drfrank.stellmach at freenet.de (Dr. Frank Stellmach) Date: Tue, 04 Aug 2009 19:01:16 +0200 Subject: [volt-nuts] Some thoughts about 3458A stability Message-ID: <4A78695C.5050301@freenet.de> Well, the voltage performance of the 3458A is best-in-class concerning linearity (better than Fluke 720A) and short term stability (transfer accuracy). Its longterm volt stability is mediocre, compared to its long 8 1/2 digit range and I really wondered, why. In the service note, 3458A-18A, it's even mentioned, that virtually all references initially show a drift behaviour which is too high for the specification of 8ppm/yr. Only by aging, and later by regular usage of the instrument, the drift will decrease to lower values. If not used, the reference may fall back into its pre-aged state! Its internal reference, the LTZ1000, is capable to deliver a stability of 1ppm/year, stated by the Linear Technology datasheet. Also, standards like the 732B (2nd generation), the 7001 and the Datron 4910, also using this same reference, provide much better drift rates. What's the reason for this obvious disagreement? I had a quick look at the reference board of the 3458A, and I think I have found the reason. The temperature of the LTZ1000 seems to be set to about 95?C, as the temperature sensing divider consists of a 15k and a 1k resistor. The LT datasheet states a typ. drift rate of 1ppm/yr at 65?C, which is 30?C less. Typically, drift rates of such a devices detoriate by a factor of 2 every 10K temperature rise. This would fit well to the observed high drift rate of the 3458A. The Fluke 732A/B references are stabilized at 45 and 48?C, and the 7001 maybe set to about 40?C only. Fluke offered a "pimped" version of the 3458A, naming it HP3458A-HFL, with a drift rate of 3ppm/yr. only. I assume, they just have set the stabilization temperature to 50-60?C, either by using their own design, or by just adding a ~70k resistor in parallel to the 15k. The disadvantage of a lower reference temperature is a longer warm up time for stabilization, as such buried zener references show a pronounced hysteresis or creep behaviour during temperature-cycling. This can be overcome by a permanent heating ( as with the 732s), or a "degaussing" technique to remove the hysteresis, as has been used in the Fluke 7001. Frank Stellmach From phk at phk.freebsd.dk Tue Aug 4 17:09:33 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Tue, 04 Aug 2009 17:09:33 +0000 Subject: [volt-nuts] Some thoughts about 3458A stability In-Reply-To: Your message of "Tue, 04 Aug 2009 19:01:16 +0200." <4A78695C.5050301@freenet.de> Message-ID: <2603.1249405773@critter.freebsd.dk> In message <4A78695C.5050301 at freenet.de>, "Dr. Frank Stellmach" writes: >This can be overcome by a permanent heating ( as with the 732s), [...] I actually thought about doing that, has anybody tried it ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From warrensjmail-one at yahoo.com Tue Aug 4 18:26:27 2009 From: warrensjmail-one at yahoo.com (WarrenS) Date: Tue, 4 Aug 2009 11:26:27 -0700 Subject: [volt-nuts] Some thoughts about 3458A stability Message-ID: I have taken JUST the opposite approach and achieved good results with cheap devices using the following rules. 1) Run them in at a combination of heat and time 2) the most important step is then Select out the good ones. 3) add a simple adjustable TC circuit that does a first order temp correction to zero the TC over a limited lab range The error due to TC that is possible is better than 0.1 PPM Total over a lab temp environment. (see attached) 4) After that DO NOT heat them up at all, Keep them at room temp. 5) Do not turn them on except when needed for short times With no high temp and no power they pretty much just sit there and don't change. Then you can use them as a reference should be use, as a transfer device, Not as a working reference. ws **************** n message <4A78695C.5050301 at freenet.de>, "Dr. Frank Stellmach" writes: >This can be overcome by a permanent heating ( as with the 732s), [...] I actually thought about doing that, has anybody tried it ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From warrensjmail-one at yahoo.com Tue Aug 4 18:31:02 2009 From: warrensjmail-one at yahoo.com (WarrenS) Date: Tue, 4 Aug 2009 11:31:02 -0700 Subject: [volt-nuts] Some thoughts about 3458A stability Message-ID: Attachment included this time Subject: Re: [volt-nuts] Some thoughts about 3458A stability I have taken JUST the opposite approach and achieved good results with cheap devices using the following rules. 1) Run them in at a combination of heat and time 2) the most important step is then Select out the good ones. 3) add a simple adjustable TC circuit that does a first order temp correction to zero the TC over a limited lab range The error due to TC that is possible is better than 0.1 PPM Total over a lab temp environment. (see attached) 4) After that DO NOT heat them up at all, Keep them at room temp. 5) Do not turn them on except when needed for short times With no high temp and no power they pretty much just sit there and don't change. Then you can use them as a reference should be use, as a transfer device, Not as a working reference. ws **************** n message <4A78695C.5050301 at freenet.de>, "Dr. Frank Stellmach" writes: >This can be overcome by a permanent heating ( as with the 732s), [...] I actually thought about doing that, has anybody tried it ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. -------------- next part -------------- A non-text attachment was scrubbed... Name: TC of #216 on 8-20-05.jpg Type: image/jpeg Size: 44736 bytes Desc: not available URL: From robert8rpi at yahoo.co.uk Wed Aug 5 07:07:52 2009 From: robert8rpi at yahoo.co.uk (Robert Atkinson) Date: Wed, 5 Aug 2009 07:07:52 +0000 (GMT) Subject: [volt-nuts] Mistery LTZ1000A transfer Standard Message-ID: <435786.44492.qm@web27105.mail.ukl.yahoo.com> Hi, I have a transfer standard that I'm trying to identify. It has no makers name or model number. It's quite small about 6.5" wide, 3" high and 9" deep. The case is blue "clamshell" with black bezel front and rear and cream front panel. It has two 4mm binding posts on the fornt and is simply marked "10 V Source" it's mains powered. Inside iis the psu and a diecast box with a pcb and the LTZ100ACH and other circitry. It has a small label saying "UK distributor Multi Sources Ltd" This was a company in Milton Keynes that was de-registered in 1994. I guess they removed the makers mark (the serial number looks like it was part of a larger label) to preserve their market. I aquired the unit in a consignment of UK MOD surplus test gear about 7 years ago. Anyone know anything about this unit? Robert G8RPI. From scottr9 at yahoo.com Fri Aug 7 15:26:22 2009 From: scottr9 at yahoo.com (Randy Scott) Date: Fri, 7 Aug 2009 08:26:22 -0700 (PDT) Subject: [volt-nuts] 3458A calibration Message-ID: <133426.31358.qm@web57702.mail.re3.yahoo.com> In the HP Journal article on the calibration of the 3458A, regarding DC calibration it says: The internal 7V Zener reference is measured relative to an externally applied traceable standard. A traceable value for this internal reference is stored in secure calibration memory... Can someone explain this to me? The 3458A's A/D converter uses +/-12V reference voltages, presumably derived from the internal 7.2V reference. Are they saying that the external 10V standard is measured using the A/D converter or that the A/D converter's 12V reference is switched to be based on the externally applied 10V and then used to measure the internal 7.2V reference? The former sounds like there would be too many variables to obtain a useful result, so the latter seems more plausible. I think that I may have answered my own question. I presume that the result of this comparison is not used directly to adjust the output of the reference, but just used to adjust later measurement results. Right? Related to this, how does the 3458A convert the 7.2V reference into the +/-12V references used by the converter? Is it as simple as a couple of opamps and some precision gain setting resistors? Wouldn't the stability of those other components then dominate the overall stability of the converter? Is something similar done in other LTZ1000-based voltage standards (such as the Datron 491x)? Thanks. Randy. From phk at phk.freebsd.dk Fri Aug 7 17:56:54 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Fri, 07 Aug 2009 17:56:54 +0000 Subject: [volt-nuts] 3458A calibration In-Reply-To: Your message of "Fri, 07 Aug 2009 08:26:22 MST." <133426.31358.qm@web57702.mail.re3.yahoo.com> Message-ID: <68610.1249667814@critter.freebsd.dk> In message <133426.31358.qm at web57702.mail.re3.yahoo.com>, Randy Scott writes: >Can someone explain this to me? The 3458A's A/D converter uses >+/-12V reference voltages, presumably derived from the internal >7.2V reference. The A/D is so precise that they can use it to calculate ratios quite precisely. They measure the external 10V and then the internal 7V and since the 12V reference does not drift much over a minute, the value of the 7V in absolute terms is now known. Later, when you run ACAL, the 7V is measured, and using the recorded absolute value, the voltage of the 12V reference is calculated. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From warrensjmail-one at yahoo.com Fri Aug 7 18:05:15 2009 From: warrensjmail-one at yahoo.com (WarrenS) Date: Fri, 7 Aug 2009 11:05:15 -0700 Subject: [volt-nuts] 3458A calibration Message-ID: Randy The general way it is done is mostly with "smoke and mirrors', otherwise known as Software scale factors and offset numbers. The 10 Cal example: Measure a known external approx 10V signal, tell the Unit what it should read for that voltage and it then changes its S/W scale factor to read that number. As far as how they keep the other things like the +- 12 supplies from dominating the stability. First they use pretty good resistors and OpAmps, BUT the trick is they say you should do an auto cal once a day or so. That measures the internal 7 volt reference number (which it stored the value of in secure memory during the last external 10V Cal) and if the 7 volts does not read the same, it knows that the unit has changed or the 7 V ref has changed. It assumes the unit changed and redoes it's S/W scale factor to make the 7V reading the same as it was during the 10V cal. It does the same sort of thing as the above for all the other dividers, and ranges. etc. It Measure a constant voltage (not necessary an accurate one) on two different ranges and using S/W scale factors makes the two reading the same. All it needs is to know the value of its 7 volt reference, and its 10Kohm resistance standard, everything else is done with S/W and comparing readings and rations What makes it all practical is its near perfect linearity and high resolution. ws ************** In the HP Journal article on the calibration of the 3458A, regarding DC calibration it says: The internal 7V Zener reference is measured relative to an externally applied traceable standard. A traceable value for this internal reference is stored in secure calibration memory... Can someone explain this to me? The 3458A's A/D converter uses +/-12V reference voltages, presumably derived from the internal 7.2V reference. Are they saying that the external 10V standard is measured using the A/D converter or that the A/D converter's 12V reference is switched to be based on the externally applied 10V and then used to measure the internal 7.2V reference? The former sounds like there would be too many variables to obtain a useful result, so the latter seems more plausible. I think that I may have answered my own question. I presume that the result of this comparison is not used directly to adjust the output of the reference, but just used to adjust later measurement results. Right? Related to this, how does the 3458A convert the 7.2V reference into the +/-12V references used by the converter? Is it as simple as a couple of opamps and some precision gain setting resistors? Wouldn't the stability of those other components then dominate the overall stability of the converter? Is something similar done in other LTZ1000-based voltage standards (such as the Datron 491x)? Thanks. Randy. From phk at phk.freebsd.dk Fri Aug 7 18:40:55 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Fri, 07 Aug 2009 18:40:55 +0000 Subject: [volt-nuts] 3458A calibration In-Reply-To: Your message of "Fri, 07 Aug 2009 11:05:15 MST." Message-ID: <68881.1249670455@critter.freebsd.dk> In message , "WarrenS" writes: >Randy > >The general way it is done is mostly with "smoke and mirrors', >otherwise known as Software scale factors and offset numbers. Calling it "smoke and mirrors" sounds weird in my ears: they have merely automated what you would have done manually to reach the same level of precision otherwise. The main difference is that the 3458A *also* gives you a very fast data-collection/digitizer, which, instead of being calibrated by twisting trimmers, is calibrated using the same math as is used for the metrology grade instrument in the same box. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From warrensjmail-one at yahoo.com Fri Aug 7 19:06:29 2009 From: warrensjmail-one at yahoo.com (WarrenS) Date: Fri, 7 Aug 2009 12:06:29 -0700 Subject: [volt-nuts] 3458A calibration Message-ID: <429EB87FA4234EFC839758D7F04E3744@WSOffice> OK, So it is not the best or most accurate technical phrase to use. My Smoke and mirrors name, was just meant as another name for an apparent 'Magic' trick, that is not magic at all once it is understood. When it is realized that there is no such thing as a voltmeter, There are just a ration meters, Then you can leave the details of how it scales the RATIO up to S/W. The 3458A thru a couple of internal steps uses the 7 volt reference as the ratio for the ADC. And its accuracy is maintained by doing regular recalibrating. Speaking of How they Automate things There are many manual ways to get a perfect +1 to -1 ratio, Anyone know exactly How the negative readings are rationed & referenced to the positive readings in the 3458A?. ws ****************** In message , "WarrenS" writes: >Randy > >The general way it is done is mostly with "smoke and mirrors', >otherwise known as Software scale factors and offset numbers. Calling it "smoke and mirrors" sounds weird in my ears: they have merely automated what you would have done manually to reach the same level of precision otherwise. The main difference is that the 3458A *also* gives you a very fast data-collection/digitizer, which, instead of being calibrated by twisting trimmers, is calibrated using the same math as is used for the metrology grade instrument in the same box. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From stijena at tapko.de Mon Aug 10 15:39:54 2009 From: stijena at tapko.de (Predrag Dukic) Date: Mon, 10 Aug 2009 17:39:54 +0200 Subject: [volt-nuts] 3458A calibration Message-ID: <7.0.1.0.1.20090810173047.01d8cd90@tapko.de> Hi all volt-nuts, A quote from previous mails about 3458a calibration: "What makes it all practical is its near perfect linearity and high resolution". Does anyone know how it is achieved? I read all that's available to me and my main question is: How to maintain this "perfect linearity". I read about multislope ramp conversion, but that is a solution meant to shorten the integration for such a big number of digits, not to improve linearity. All sorts of effects come to my mind...: nonlinear active component leakage, voltage coeficients in resistors (also resistive dividers), nonlinear dielectric absorption in integration capacitors etc etc... Does anyone has some 3458a AD schematics? Service manual can't be downloaded from internet... Predrag Dukic From phk at phk.freebsd.dk Mon Aug 10 15:58:07 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Mon, 10 Aug 2009 15:58:07 +0000 Subject: [volt-nuts] 3458A calibration In-Reply-To: Your message of "Mon, 10 Aug 2009 17:39:54 +0200." <7.0.1.0.1.20090810173047.01d8cd90@tapko.de> Message-ID: <50014.1249919887@critter.freebsd.dk> In message <7.0.1.0.1.20090810173047.01d8cd90 at tapko.de>, Predrag Dukic writes: >How to maintain this "perfect linearity". I read about multislope >ramp conversion, but that is a solution meant to shorten the >Does anyone has some 3458a AD schematics? Service manual can't be >downloaded from internet... The ADC in the HP3458A derives its linearity from a very small handful of components, most importantly a quite small capacitor (~120pF), by converting the measurement of voltage to a measurement of time. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From bruce.griffiths at xtra.co.nz Mon Aug 10 21:13:14 2009 From: bruce.griffiths at xtra.co.nz (Bruce Griffiths) Date: Tue, 11 Aug 2009 09:13:14 +1200 Subject: [volt-nuts] 3458A calibration In-Reply-To: <50014.1249919887@critter.freebsd.dk> References: <50014.1249919887@critter.freebsd.dk> Message-ID: <4A808D6A.3020102@xtra.co.nz> Poul-Henning Kamp wrote: > In message <7.0.1.0.1.20090810173047.01d8cd90 at tapko.de>, Predrag Dukic writes: > > >> How to maintain this "perfect linearity". I read about multislope >> ramp conversion, but that is a solution meant to shorten the >> > > >> Does anyone has some 3458a AD schematics? Service manual can't be >> downloaded from internet... >> > > The ADC in the HP3458A derives its linearity from a very small handful > of components, most importantly a quite small capacitor (~120pF), > by converting the measurement of voltage to a measurement of time. > > The April 1989 HP journal article on the 3458A states that the integrator uses a 330pF feedback capacitor. The effect of dielectric absorption in the integrator feedback capacitor is kept small by using a capacitor with low dielectric absorption and by keeping the maximum charge stored in the capacitor a small fraction of the full scale integrator input current integration time product. The effect of dielectric absorption can be minimised by ensuring that the average voltage across the integrator feedback capacitor remains low over the integration cycle. HP/Agilent have several patents covering this aspect of DVM integrator runup cycles. However the runup cycle of the 3458 unlike some other HP/Agilent DVMs doesn't appear to use this technique. Later HP DVMs do use such techniques. Bruce From scottr9 at yahoo.com Mon Aug 10 21:29:21 2009 From: scottr9 at yahoo.com (Randy Scott) Date: Mon, 10 Aug 2009 14:29:21 -0700 (PDT) Subject: [volt-nuts] 3458A calibration In-Reply-To: <4A808D6A.3020102@xtra.co.nz> Message-ID: <903928.69508.qm@web57703.mail.re3.yahoo.com> > The effect of dielectric absorption can be minimised by > ensuring that the average voltage across the integrator feedback > capacitor remains low over the integration cycle. > HP/Agilent have several patents covering this aspect of DVM > integrator runup cycles. Are you referring to what HP calls their "charge-balancing" A/D converter where during the run-up phase of the conversion they attempt to keep the output of the integrator balanced around 0 volts? The Agilent 34401A does something like this and then uses a second, fast A/D converter to replace the run-down phase. > However the runup cycle of the 3458 unlike some other > HP/Agilent DVMs doesn't appear to use this technique. > Later HP DVMs do use such techniques. It would seem that with an A/D, like the 3458A's, that relies on multi-slope run-down, it would be advantageous to keep the integrator output as high as possible at the end of the run-up phase to maximize the resolution achieved during run-down. Randy. From bruce.griffiths at xtra.co.nz Mon Aug 10 21:41:20 2009 From: bruce.griffiths at xtra.co.nz (Bruce Griffiths) Date: Tue, 11 Aug 2009 09:41:20 +1200 Subject: [volt-nuts] 3458A calibration In-Reply-To: <903928.69508.qm@web57703.mail.re3.yahoo.com> References: <903928.69508.qm@web57703.mail.re3.yahoo.com> Message-ID: <4A809400.5090202@xtra.co.nz> Randy Scott wrote: >> The effect of dielectric absorption can be minimised by >> ensuring that the average voltage across the integrator feedback >> capacitor remains low over the integration cycle. >> HP/Agilent have several patents covering this aspect of DVM >> integrator runup cycles. >> > > Are you referring to what HP calls their "charge-balancing" A/D converter where during the run-up phase of the conversion they attempt to keep the output of the integrator balanced around 0 volts? > > The Agilent 34401A does something like this and then uses a second, fast A/D converter to replace the run-down phase. > > The 34401 runup algorithm is a little more complex than that, it actually sums the output of the integrator with the input to the integrator and uses that as the comparator input. The term balanced is ambiguous, I mean that the algorithm attempts to keep the integral of the integrator output constant. Even lower dielectric absorption effects are achieved if a term proportional to the integral of the integrator output is included in effect a second order delta sigma runup cycle. >> However the runup cycle of the 3458 unlike some other >> HP/Agilent DVMs doesn't appear to use this technique. >> Later HP DVMs do use such techniques. >> > > It would seem that with an A/D, like the 3458A's, that relies on multi-slope run-down, it would be advantageous to keep the integrator output as high as possible at the end of the run-up phase to maximize the resolution achieved during run-down. > Randy. > Bruce From jfor at quik.com Mon Aug 10 21:43:22 2009 From: jfor at quik.com (J. Forster) Date: Mon, 10 Aug 2009 14:43:22 -0700 (PDT) Subject: [volt-nuts] 3458A calibration In-Reply-To: <903928.69508.qm@web57703.mail.re3.yahoo.com> References: <903928.69508.qm@web57703.mail.re3.yahoo.com> Message-ID: <2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> Keeping the voltage across the integrating capacitor (0 is a special case of constant) is a good idea because it solves the problem of dC/dV (voltage coefficient of capacitance). -John ============ >> The effect of dielectric absorption can be minimised by >> ensuring that the average voltage across the integrator feedback >> capacitor remains low over the integration cycle. >> HP/Agilent have several patents covering this aspect of DVM >> integrator runup cycles. > > Are you referring to what HP calls their "charge-balancing" A/D converter > where during the run-up phase of the conversion they attempt to keep the > output of the integrator balanced around 0 volts? [snip] From bruce.griffiths at xtra.co.nz Mon Aug 10 21:51:58 2009 From: bruce.griffiths at xtra.co.nz (Bruce Griffiths) Date: Tue, 11 Aug 2009 09:51:58 +1200 Subject: [volt-nuts] 3458A calibration In-Reply-To: <2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> References: <903928.69508.qm@web57703.mail.re3.yahoo.com> <2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> Message-ID: <4A80967E.7080203@xtra.co.nz> For the 3458A integrator feedback capacitor nonlinearity isnt an issue (as long as there is no hysteresis) as it cancels out during the rundown phase. For DVMs like the 34401A which use an ADC to sample the integrator output integrator feedback capacitor nonlinearity is important. Bruce J. Forster wrote: > Keeping the voltage across the integrating capacitor (0 is a special case > of constant) is a good idea because it solves the problem of dC/dV > (voltage coefficient of capacitance). > > -John > > ============ > > > >>> The effect of dielectric absorption can be minimised by >>> ensuring that the average voltage across the integrator feedback >>> capacitor remains low over the integration cycle. >>> HP/Agilent have several patents covering this aspect of DVM >>> integrator runup cycles. >>> >> Are you referring to what HP calls their "charge-balancing" A/D converter >> where during the run-up phase of the conversion they attempt to keep the >> output of the integrator balanced around 0 volts? >> > [snip] > > > From gbusg at comcast.net Tue Aug 11 03:29:10 2009 From: gbusg at comcast.net (Greg Burnett) Date: Mon, 10 Aug 2009 21:29:10 -0600 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard? References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> <4A80967E.7080203@xtra.co.nz> Message-ID: <006201ca1a33$e4565d80$6501a8c0@gb02> Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC Reference Standard Does anyone know of an affordable substitute for these batteries? Fluke's web site doesn't even recognize their own part number for these batteries, but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's price a set of four would cost $269.96! According to Newark their physical size is 70x45x107mm. The old set that were in my 732A are marked, "PT56 6V 5AH Made in China". So someone installed these as substitutes. I searched the internet for "PT56" but didn't see anything linking that number to a standard or generic battery. Thanks, Greg From jfor at quik.com Tue Aug 11 03:34:29 2009 From: jfor at quik.com (J. Forster) Date: Mon, 10 Aug 2009 20:34:29 -0700 (PDT) Subject: [volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard? In-Reply-To: <006201ca1a33$e4565d80$6501a8c0@gb02> References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> <4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> Message-ID: <3116.12.6.201.245.1249961669.squirrel@popacctsnew.quik.com> Try a place that sells to professional alarm installers. -John ============= > Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC > Reference Standard > > Does anyone know of an affordable substitute for these batteries? Fluke's > web site doesn't even recognize their own part number for these batteries, > but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's > price a set of four would cost $269.96! From gbusg at comcast.net Tue Aug 11 03:46:51 2009 From: gbusg at comcast.net (Greg Burnett) Date: Mon, 10 Aug 2009 21:46:51 -0600 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard? References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com><4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> <3116.12.6.201.245.1249961669.squirrel@popacctsnew.quik.com> Message-ID: <007501ca1a36$5ceb4880$6501a8c0@gb02> ----- Original Message ----- From: "J. Forster" Try a place that sells to professional alarm installers. -John ============= OK, good suggestion. I'll try that. Thanks, Greg From ed_palmer at sasktel.net Tue Aug 11 06:36:36 2009 From: ed_palmer at sasktel.net (Ed Palmer) Date: Tue, 11 Aug 2009 00:36:36 -0600 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard? In-Reply-To: <006201ca1a33$e4565d80$6501a8c0@gb02> References: <903928.69508.qm@web57703.mail.re3.yahoo.com> <2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> <4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> Message-ID: <4A811174.9090508@sasktel.net> Hi Greg, Do you have to use the Fluke battery? Can't you use a regular one? When I looked at Newark for 4 to 5 AH @ 6V lead acid, I found 6 batteries priced from $8.17 to $38.65 each. Digikey has two in the $10 to $12 range. In any case, you might find that shipping costs make a mail order purchase unattractive. You should definitely compare prices at a local battery store. Ed Greg Burnett wrote: > Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC > Reference Standard > > Does anyone know of an affordable substitute for these batteries? Fluke's > web site doesn't even recognize their own part number for these batteries, > but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's > price a set of four would cost $269.96! > > According to Newark their physical size is 70x45x107mm. > > The old set that were in my 732A are marked, "PT56 6V 5AH Made in China". So > someone installed these as substitutes. I searched the internet for "PT56" > but didn't see anything linking that number to a standard or generic > battery. > > Thanks, > Greg > From drfrank.stellmach at freenet.de Tue Aug 11 06:55:50 2009 From: drfrank.stellmach at freenet.de (Dr. Frank Stellmach) Date: Tue, 11 Aug 2009 08:55:50 +0200 Subject: [volt-nuts] 3458A calibration - linearity Message-ID: <4A8115F6.6050205@freenet.de> Predrag, Please download the HP Journal Vol 40, #2 (April 1989) from here: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1989-04.pdf The multislope rundown conversion is explained in detail (p.8 ff), also why its linearity is nearly perfect. The main negative effect of multislope A/D conversion, which is cancelled in the 3458A, is the charge injection by the analogue switches. A strictly symmetrical switching pattern is used for every possible situation. So the charge injection effects are cancelld out. The external passive components (R,C) are relatively uncritical compared to this effect. But besides the linearity of the A/D converter, there is another nonlinearity in the 3458A. On the 1000V range, a quadratic nonlinearity over increasing input voltage is introduced by dissipation effect in the 100:1 divider. Therefore, up to 12ppm additional error has to be taken into account. That's a big disadvantga of this AUTOCAL technique. Other longscale DVMs use external 1000V / 500V reference points to calculate and cancel this effect. Frank Stellmach From phill.r1 at btinternet.com Tue Aug 11 10:36:12 2009 From: phill.r1 at btinternet.com (Roy Phillips) Date: Tue, 11 Aug 2009 11:36:12 +0100 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: <006201ca1a33$e4565d80$6501a8c0@gb02> References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com><4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> Message-ID: Hello Greg I am sure that you can find a suitable replacement "sealed lead acid" battery from a number of sources for considerably less than your quoted amount. Due to the content, most of these are made in China or other Far Eastern Country - regardless of the "name" of the manufacturer. I have two Fluke 731B's, and these use Ni-Cad batteries. As we can see, these were "dropped" as a back-up" power source, due to the corrosive damage they caused to the PCB. Regardless, I still get a very good performance from these "ancient" DC standards. Incidentally, if anyone finds it hard to obtain information from the Fluke US and European websites, try Fluke in Australia - much more generous in manuals for older items. Roy From: "Greg Burnett" To: "Discussion of precise voltage measurement" Sent: Tuesday, August 11, 2009 4:29 AM Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? > Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC > Reference Standard > > Does anyone know of an affordable substitute for these batteries? Fluke's > web site doesn't even recognize their own part number for these batteries, > but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's > price a set of four would cost $269.96! > > According to Newark their physical size is 70x45x107mm. > > The old set that were in my 732A are marked, "PT56 6V 5AH Made in China". > So > someone installed these as substitutes. I searched the internet for "PT56" > but didn't see anything linking that number to a standard or generic > battery. > > Thanks, > Greg > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > From masondg44 at comcast.net Tue Aug 11 14:04:29 2009 From: masondg44 at comcast.net (Dave M) Date: Tue, 11 Aug 2009 10:04:29 -0400 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com><4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> Message-ID: <4AAA8D51B59040FE8CEE1D98216FA0D4@D77M7BF1> ----- Original Message ----- From: "Greg Burnett" To: "Discussion of precise voltage measurement" Sent: Monday, August 10, 2009 11:29 PM Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? > Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC > Reference Standard > > Does anyone know of an affordable substitute for these batteries? Fluke's > web site doesn't even recognize their own part number for these batteries, > but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's > price a set of four would cost $269.96! > > According to Newark their physical size is 70x45x107mm. > > The old set that were in my 732A are marked, "PT56 6V 5AH Made in China". > So > someone installed these as substitutes. I searched the internet for "PT56" > but didn't see anything linking that number to a standard or generic > battery. > > Thanks, > Greg > Greg, These are plain 6-volt sealed lead-acid (SLA) batteries, with an obvious 5AH rating. Just get on the web and find 6V/5AH SLA batteries with the same dimensions and terminals, and you're all set. Some battery vendors are: http://www.batterywholesale.com/ http://www.batterystation.com/gelcell.htm http://www.nicdladyonline.com/shop/?shop=1&cat=17 http://www.arizonabattery.com Google for SLA Batteries Dave M masondg44 at comcast dot net I went to a bookstore and asked the saleswoman, "Where's the self-help section?" She said if she told me, it would defeat the purpose. From holrum at hotmail.com Tue Aug 11 16:27:59 2009 From: holrum at hotmail.com (Mark Sims) Date: Tue, 11 Aug 2009 16:27:59 +0000 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: References: Message-ID: Be very careful when getting the batteries... They come with either 0.25" or 0.187" wide tabs. Make sure that they match your terminals. ---------------------------------------- _________________________________________________________________ Get your vacation photos on your phone! http://windowsliveformobile.com/en-us/photos/default.aspx?&OCID=0809TL-HM From garnere at gmail.com Tue Aug 11 16:41:42 2009 From: garnere at gmail.com (Eric Garner) Date: Tue, 11 Aug 2009 09:41:42 -0700 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: <4AAA8D51B59040FE8CEE1D98216FA0D4@D77M7BF1> References: <903928.69508.qm@web57703.mail.re3.yahoo.com> <2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> <4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> <4AAA8D51B59040FE8CEE1D98216FA0D4@D77M7BF1> Message-ID: If you are in the US, you might try Batteries Plus for a local option (if they have one near you) http://www.batteriesplus.com/ I've had good luck with them for replacements for my UPS batteries. theyare not as cheap as online places, but there's no shipping and you get instant gratification. -Eric On Tue, Aug 11, 2009 at 7:04 AM, Dave M wrote: > ----- Original Message ----- From: "Greg Burnett" > To: "Discussion of precise voltage measurement" > Sent: Monday, August 10, 2009 11:29 PM > Subject: [volt-nuts] Affordable batteries for Fluke 732A DC > ReferenceStandard? > > >> Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC >> Reference Standard >> >> Does anyone know of an affordable substitute for these batteries? Fluke's >> web site doesn't even recognize their own part number for these batteries, >> but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's >> price a set of four would cost $269.96! >> >> According to Newark their physical size is 70x45x107mm. >> >> The old set that were in my 732A are marked, "PT56 6V 5AH Made in China". >> So >> someone installed these as substitutes. I searched the internet for "PT56" >> but didn't see anything linking that number to a standard or generic >> battery. >> >> Thanks, >> Greg >> > > > > Greg, > These are plain 6-volt sealed lead-acid (SLA) batteries, with an obvious 5AH > rating. ?Just get on the web and find 6V/5AH SLA batteries with the same > dimensions and terminals, and you're all set. > Some battery vendors are: > http://www.batterywholesale.com/ > http://www.batterystation.com/gelcell.htm > http://www.nicdladyonline.com/shop/?shop=1&cat=17 > http://www.arizonabattery.com > > Google for SLA Batteries > > Dave M > masondg44 at comcast dot net > > I went to a bookstore and asked the saleswoman, "Where's the > self-help section?" She said if she told me, it would defeat the > purpose. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- --Eric _________________________________________ Eric Garner From holrum at hotmail.com Tue Aug 11 19:02:11 2009 From: holrum at hotmail.com (Mark Sims) Date: Tue, 11 Aug 2009 19:02:11 +0000 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: References: Message-ID: Ebay item 390080814098... 4 pieces for $17.30 (total!) plus 10 bucks shipping... can't beat that with a stick ---------------------------------------- _________________________________________________________________ Windows Live?: Keep your life in sync. http://windowslive.com/explore?ocid=PID23384::T:WLMTAGL:ON:WL:en-US:NF_BR_sync:082009 From jfor at quik.com Tue Aug 11 19:20:38 2009 From: jfor at quik.com (J. Forster) Date: Tue, 11 Aug 2009 12:20:38 -0700 (PDT) Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: References: Message-ID: <2108.12.6.201.40.1250018438.squirrel@popacctsnew.quik.com> That vendor seems pretty well on the up and up, but try and get fresh stock. Gel cells rot on the shelf. Best, -John ========== > Ebay item 390080814098... 4 pieces for $17.30 (total!) plus 10 bucks > shipping... can't beat that with a stick > > > ---------------------------------------- From gbusg at comcast.net Wed Aug 12 07:14:48 2009 From: gbusg at comcast.net (Greg Burnett) Date: Wed, 12 Aug 2009 01:14:48 -0600 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com><4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02><4AAA8D51B59040FE8CEE1D98216FA0D4@D77M7BF1> Message-ID: <003201ca1b1c$945345c0$6501a8c0@gb02> ...Great information and suggestions by everyone! (I'd not thought of all those possibilities.) Now the ball is in my court to measure the old batteries' outside dimensions, tab dimensions and tab positions - and then narrow the choice down to batteries that will fit. One thing I've learned from this so far is that apparently each battery manufacturer (or re-seller) uses their own custom battery part number designation. Too bad they didn't do a better job of standardizing? One important consideration is that the battery connection tabs must align with the corresponding holes in Fluke's internal aluminum top plate. (This wouldn't be a consideration for the vast majority of similar applications, but in this case Fluke's internal aluminum plate "expects" the tabs to be precisely positioned.) Thanks John, Ed, Roy, Dave, Mark and Eric for all your help! Greg From jfor at quik.com Wed Aug 12 14:09:27 2009 From: jfor at quik.com (J. Forster) Date: Wed, 12 Aug 2009 07:09:27 -0700 (PDT) Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: <003201ca1b1c$945345c0$6501a8c0@gb02> References: <903928.69508.qm@web57703.mail.re3.yahoo.com><2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com><4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02><4AAA8D51B59040FE8CEE1D98216FA0D4@D77M7BF1> <003201ca1b1c$945345c0$6501a8c0@gb02> Message-ID: <1082.12.6.201.210.1250086167.squirrel@popacctsnew.quik.com> Many battery suppliers have cross-reference charts. That might make life easier. -John ============ > ...Great information and suggestions by everyone! (I'd not thought of all > those possibilities.) > > Now the ball is in my court to measure the old batteries' outside > dimensions, tab dimensions and tab positions - and then narrow the choice > down to batteries that will fit. One thing I've learned from this so far > is > that apparently each battery manufacturer (or re-seller) uses their own > custom battery part number designation. Too bad they didn't do a better > job > of standardizing? > > One important consideration is that the battery connection tabs must align > with the corresponding holes in Fluke's internal aluminum top plate. (This > wouldn't be a consideration for the vast majority of similar applications, > but in this case Fluke's internal aluminum plate "expects" the tabs to be > precisely positioned.) > > Thanks John, Ed, Roy, Dave, Mark and Eric for all your help! > > Greg From ed_palmer at sasktel.net Wed Aug 12 14:45:52 2009 From: ed_palmer at sasktel.net (Ed Palmer) Date: Wed, 12 Aug 2009 08:45:52 -0600 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC ReferenceStandard? In-Reply-To: <003201ca1b1c$945345c0$6501a8c0@gb02> References: <903928.69508.qm@web57703.mail.re3.yahoo.com> <2122.12.6.201.191.1249940602.squirrel@popacctsnew.quik.com> <4A80967E.7080203@xtra.co.nz> <006201ca1a33$e4565d80$6501a8c0@gb02> <4AAA8D51B59040FE8CEE1D98216FA0D4@D77M7BF1> <003201ca1b1c$945345c0$6501a8c0@gb02> Message-ID: <4A82D5A0.7060905@sasktel.net> Two more things to keep in mind... I was looking for a replacement for an old 12V 5AH gel cell. It turnes out that newer batteries are specified differently than the old ones were. To get a new battery the same physical size as the old one, I had to look at 12V 7AH batteries! If you're considering a local purchase, take the battery carrier, holder, unit, whatever with you to the battery store so that you can test the fit of the batteries. Ed Greg Burnett wrote: > ...Great information and suggestions by everyone! (I'd not thought of all > those possibilities.) > > Now the ball is in my court to measure the old batteries' outside > dimensions, tab dimensions and tab positions - and then narrow the choice > down to batteries that will fit. One thing I've learned from this so far is > that apparently each battery manufacturer (or re-seller) uses their own > custom battery part number designation. Too bad they didn't do a better job > of standardizing? > > One important consideration is that the battery connection tabs must align > with the corresponding holes in Fluke's internal aluminum top plate. (This > wouldn't be a consideration for the vast majority of similar applications, > but in this case Fluke's internal aluminum plate "expects" the tabs to be > precisely positioned.) > > Thanks John, Ed, Roy, Dave, Mark and Eric for all your help! > > Greg > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > From kilodelta4foxmike at gmail.com Thu Aug 13 23:41:38 2009 From: kilodelta4foxmike at gmail.com (Brian Kirby) Date: Thu, 13 Aug 2009 18:41:38 -0500 Subject: [volt-nuts] More Precision Resistors Message-ID: <4A84A4B2.60005@gmail.com> You can also find precision resistors in a lot of older bridges at hamfest. I have seen a lot of Leeds and Northrup bridges available. If the bridge is inop, you usually can get it for close to nothing. Sometimes just one string of resistors will have been burned out and the rest will be available. Brian KD4FM From jfor at quik.com Thu Aug 13 23:58:44 2009 From: jfor at quik.com (J. Forster) Date: Thu, 13 Aug 2009 16:58:44 -0700 (PDT) Subject: [volt-nuts] More Precision Resistors In-Reply-To: <4A84A4B2.60005@gmail.com> References: <4A84A4B2.60005@gmail.com> Message-ID: <1664.12.6.201.137.1250207924.squirrel@popacctsnew.quik.com> Not all will be really useful as they are open style, wirewound on mica cards, and pretty fragile. Best, -John ============= > You can also find precision resistors in a lot of older bridges at > hamfest. I have seen a lot of Leeds and Northrup bridges available. If > the bridge is inop, you usually can get it for close to nothing. > Sometimes just one string of resistors will have been burned out and the > rest will be available. > > > > Brian KD4FM From kilodelta4foxmike at gmail.com Fri Aug 14 01:29:09 2009 From: kilodelta4foxmike at gmail.com (Brian Kirby) Date: Thu, 13 Aug 2009 20:29:09 -0500 Subject: [volt-nuts] More Precision Resistors In-Reply-To: <1664.12.6.201.137.1250207924.squirrel@popacctsnew.quik.com> References: <4A84A4B2.60005@gmail.com> <1664.12.6.201.137.1250207924.squirrel@popacctsnew.quik.com> Message-ID: <4A84BDE5.50609@gmail.com> It probably depends when they were made. Most that I have seen, have been wire-wound on waxed paper bobbins. I'm just pointing out some sources - everybody's mileage will vary. J. Forster wrote: > Not all will be really useful as they are open style, wirewound on mica > cards, and pretty fragile. > > Best, > -John > > ============= > > > >> You can also find precision resistors in a lot of older bridges at >> hamfest. I have seen a lot of Leeds and Northrup bridges available. If >> the bridge is inop, you usually can get it for close to nothing. >> Sometimes just one string of resistors will have been burned out and the >> rest will be available. >> >> >> >> Brian KD4FM >> > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > From phk at phk.freebsd.dk Sat Aug 15 23:00:27 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Sat, 15 Aug 2009 23:00:27 +0000 Subject: [volt-nuts] Backing up HP3458A NVRAM Message-ID: <6187.1250377227@critter.freebsd.dk> Old NVRAM batteries are a common affliction for HP3458A units, and various hardware fixes have been floated. The trouble of course, is that if you loose the content of the chip that contains your calibration constants, you will need a new calibration of your meter, even though the error domain is entirely within the outguard part. However, I belive there also is a software workaround, and I'm documenting it here, so that you can perform step 1, even if step 2 has not been found and tested yet. The 3458A has a number of undocumented commands, amongst these: XYZZY (try it :-) MREAD MWRITE JSR MREAD allows you to read one 16bit memory word, for instance: MREAD 4 MREAD 6 will get you the two halfwords of the RESET vector. The Calibration NVRAM is located in the top byte of the memory at address 0x60000...0x60fff, so by issuing 2048 GPIB commands: MREAD 393216 MREAD 393218 ... MREAD 397308 MREAD 397310 And recording the output, you can create a backup copy of the entire calibration NVRAM on your computer. Now, if the battery in your NVRAM finally dies, your system will come up with some variant of a calibration error. You can then either unsolder the NVRAM, program another suitable device (FRAM ?) with the content of your backup file, and mount that in the PCB(-socket) instead. OR, and this is the interesting part: It should then be possible to write this backup copy back using MWRITE commands, RESET the 3458A and continue working, as long as you do not unplug power from it. I have not tried this yet, because I have not yet figured out the magic sequence to writing-enable the NVRAM, there is a layer of sw/hw protection to prevent just that. So that awaits confirmation at some point. But those of you with ancient NVRAMs, can at least make a backup copy now, before you need it. It is not my impression that the other two NVRAMs are as important, they "only" contain stored functions and similar stuff, but if you want a copy of those as well, I belive they are located in full words from 0x120000...0x12ffff (1179648...1245182 decimal) Enjoy, Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at 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. From holrum at hotmail.com Sun Aug 16 01:26:48 2009 From: holrum at hotmail.com (Mark Sims) Date: Sun, 16 Aug 2009 01:26:48 +0000 Subject: [volt-nuts] More Precision Resistors In-Reply-To: References: Message-ID: I recently got in an ESI DB877 8 decade resistance box (12 Megohms at 0.1 ohms/step). This box is chock full of 0.01% wire wound resistors (1R and 5x2R resistors per decade) and a pair of nested four gang switches/dials. The 1K resistor was pretty much toast. I replaced it with the 900.98 ohm and 100.02 ohm resistors from a Tektronix 067-0503-00 precision DC divider (paralleled with a selected 1 Meg resistor). That resistor is now within around 0.0005%. The 10K resistor was also off, reading around 10015 ohms. Paralleling it with a selected resistor pair also got it to around 0.0005%. All is well with this wonderful little box and all values are now well within spec (0.01%). Most are under 0.003%. However, things could be better for this volt nut. The 100K and 5x200K resistors are all around 8-9 ohms high. Does anybody know of a cheap source of 1 to 5 gohm resistors (actually 1.250 gohm, 1x2.500 gohm, and 4x4.000 gohm, would be best and would get that whole decade under 0.001%)? Mouser/Digikey/etc have them for around 4 bucks a pop... cheaper is better... Now, if I could also find a -0.0382 ohm resistor to cancel out the zero ohm lead/switch bias... ---------------------------------------- _________________________________________________________________ Windows Live?: Keep your life in sync. http://windowslive.com/explore?ocid=PID23384::T:WLMTAGL:ON:WL:en-US:NF_BR_sync:082009 From warrensjmail-one at yahoo.com Sun Aug 16 05:52:48 2009 From: warrensjmail-one at yahoo.com (WarrenS) Date: Sat, 15 Aug 2009 22:52:48 -0700 Subject: [volt-nuts] More Precision Resistors1 Message-ID: <2C362B85347D4C79990F40A65CD7EFB6@WSOffice> Mark Allen Bradley did make 100 meg 1/4 w P# CB1075 ?? I picked a large number of these and just series them for the exact same thing. not pretty but effective and they were cheap when bought in quantities of a hundred long ago. That with the additional of the digikey 1000 meg, makes a good set of adjustments. Still not the greatest thing for 4G. If I get real desperate, I'll parallel with a good quality high value resistor to get the value under and then series it with a small value fixed &/or pot. Some of my precision dividers have quite a bit of tweaks inside, but they are dead nuts on. To get the neg ohms, Two ways I've used: Bringing out an extra lead from the other side of the switch, for 4-wire ohms, will sometimes do it. The other way that works, is to add a small resistance to make it a nice constant extra 0.10 Ohms (One LS dial setting) high on all ranges and move the dial 1 count on the low order switch (and add an '11'). ws From robert8rpi at yahoo.co.uk Sun Aug 16 13:58:15 2009 From: robert8rpi at yahoo.co.uk (Robert Atkinson) Date: Sun, 16 Aug 2009 13:58:15 +0000 (GMT) Subject: [volt-nuts] More Precision Resistors In-Reply-To: Message-ID: <151775.83775.qm@web27104.mail.ukl.yahoo.com> I picked up a DB-877 at the De Anza swap meet in the bay area a few years ago. It was grubby but a bargain at $40! Works perfectly after a bit of cleaning and some lubrication of the concentric shafts. These a realy good units, very compact for 8 decades. 0.01% is good enought for me as a decade box. The swap meet is well worth a vist. Dispite many vists to the bay area only on coincided with the meet. Robert G8RPI. --- On Sun, 16/8/09, Mark Sims wrote: > From: Mark Sims > Subject: [volt-nuts] More Precision Resistors > To: volt-nuts at febo.com > Date: Sunday, 16 August, 2009, 2:26 AM > > I recently got in an ESI DB877 8 decade resistance box (12 > Megohms at 0.1 ohms/step).???This box is > chock full of 0.01% wire wound resistors (1R and 5x2R > resistors per decade) and a pair of nested four gang > switches/dials. > > The 1K resistor was pretty much toast.? I replaced it > with the 900.98 ohm and 100.02 ohm resistors from a > Tektronix 067-0503-00 precision DC divider (paralleled with > a selected 1 Meg resistor).? That resistor is now > within around 0.0005%. > > The 10K resistor was also off,? reading around 10015 > ohms.? Paralleling it with a selected resistor pair > also got it to around 0.0005%. > > All is well with this wonderful little box and all values > are now well within spec (0.01%).???Most are > under 0.003%.? However,? things could be better > for this volt nut.? The 100K and 5x200K resistors are > all around 8-9 ohms high.? > > Does anybody know of a cheap source of 1 to 5 gohm? > resistors (actually 1.250 gohm,? 1x2.500 gohm,? > and 4x4.000 gohm,???would be best and would > get that whole decade under 0.001%)?? > Mouser/Digikey/etc have them for around 4 bucks a pop... > cheaper is better... > > Now,? if I could also find a -0.0382 ohm resistor to > cancel out the zero ohm lead/switch bias... > > ---------------------------------------- > > > _________________________________________________________________ > Windows Live?: Keep your life in sync. > http://windowslive.com/explore?ocid=PID23384::T:WLMTAGL:ON:WL:en-US:NF_BR_sync:082009 > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > From holrum at hotmail.com Sun Aug 16 16:27:23 2009 From: holrum at hotmail.com (Mark Sims) Date: Sun, 16 Aug 2009 16:27:23 +0000 Subject: [volt-nuts] More Precision Resistors In-Reply-To: References: Message-ID: IET still makes the DB877... a shiny new one will set you back $6000! Several vendors sell used ones for $1500-$2000. There is one on Ebay for $700. I paid $75 for mine (plus $25 for the Tek divider I used to fix the thing - ESI also made the resistors in it). It was in really good condition. I also have a DB655 and a couple of the ESI Kelvin-Varley dividers that use the same cone-centric stack of knobs. If I just patch the 100K resistor, all the setting will be under 0.005%. For around 40 bucks it looks like I can get the 100K decade pretty much perfect. I could also also tune up the megohm decade with some 100 gohm resistors.... I considered adding a series resistance to get the 0.032 zero ohm bias to 0.10 ohms, but that would affect the performance of the other ranges. Also the bias is not a constant value. It does change some depending upon the path through the switches. I treated all the switches with Stabilant 22 (magic stuff... and it darn well better be at $50/5mL) which really helped. ---------------------------------------- I picked up a DB-877 at the De Anza swap meet in the bay area a few years ago. It was grubby but a bargain at $40! _________________________________________________________________ Get back to school stuff for them and cashback for you. http://www.bing.com/cashback?form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHYCB_BackToSchool_Cashback_BTSCashback_1x1 From scottr9 at yahoo.com Tue Aug 18 13:31:45 2009 From: scottr9 at yahoo.com (Randy Scott) Date: Tue, 18 Aug 2009 06:31:45 -0700 (PDT) Subject: [volt-nuts] 3458A AC board Message-ID: <382937.60392.qm@web57701.mail.re3.yahoo.com> Gents, I have a 3458A on its way to me that fails self test with the error "202 Hardware Failure - Slave Test: AC Board". The assembly-level repair manual calls for replacing the AC converter board (at $1200 minus a $200 trade-in for the broken board). Assuming that it is actually broken and its not something simple, does any one have an opinion on the repairability of the board? Would the component-level "information packet" be worthwhile? Or, should I just bite the bullet and buy a new board from Agilent? Thanks. Randy. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com From holrum at hotmail.com Tue Aug 18 17:47:29 2009 From: holrum at hotmail.com (Mark Sims) Date: Tue, 18 Aug 2009 17:47:29 +0000 Subject: [volt-nuts] 3458A AC board In-Reply-To: References: Message-ID: First thing to do is get the meter in and to try and debug the AC board. It could be something as simple as a flakey connection or bad cap/diode/transistor/moon phase modulator. If you have a (very good) friend with another 3458A it would be good to try swapping the AC board to verify that is actually the problem. Next I would probably get the component level documentation try to debug the unit with that info. Only then would I spring for a new AC board (or probably just let HP fix the thing). It would not be good to buy a $1000 board that does not fix the problem... _________________________________________________________________ With Windows Live, you can organize, edit, and share your photos. http://www.windowslive.com/Desktop/PhotoGallery From holrum at hotmail.com Thu Aug 20 22:30:43 2009 From: holrum at hotmail.com (Mark Sims) Date: Thu, 20 Aug 2009 22:30:43 +0000 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard? In-Reply-To: References: Message-ID: OK, I just got in a 732A with bad batteries... hint, SLA batteries should not rattle with a crunchy sound. The original batteries were PowerSonic PS604's with a flat top and wire leads/molex type connector coming out the side of the battery at the top. The battery "terminals" were under the sealed flat top. This battery style was once used in about every emergency exit light ever made, but it is no longer made... bummer. Your easiest solution is to use two PS1229 12V 2.9AH batteries. They fit in the space with room to spare. No problem. You do have to use some rigid foam, etc to shim up the excess space. You also have to bridge over the unused battery connectors on the PCB. The biggest problem is you lose 25% of the capacity (or 33% of the capacity available with modern 4.5 AH capacity). The problem with current production PS604 cells is their size. Although their case is slightly shorter than the original battery, the new ones have spade lug terminals that stick up out of the top of the battery and are bent over at a right angle. I went to the local battery/light bulb store (www.evssupply.com - highly recommended) and checked out the current production PS604 cells. The ones I looked at are made by PowerSonic. Other brands may have slightly different case sizes... I was convinced that they would work. I selected four cells that had the bend in the terminal closest to the battery case. I also bought four 10" wire harnesses with the molex type connector on one end and insulated spade lugs on the other. Total cost was about $50. I modified the spade lugs by shaving part of the bottom of the spade lug insulation off. I pressed down on the battery terminals as much as possible to lower their height. I managed to shoehorn the new cells into the 732A case, but, alas, when I tried to install the battery unit back into the 732A, the top plate of the case where the PC board is was bowed up enough so that it would not mate with the connector in the 732A... Leaving screws loose, etc made no difference.. crap... Looking at the construction of the 732A battery case, I noticed that the bottom plate of the case was a small rectangular dish about 1/4" deep that is mounted bottom side up. The batteries sit on the flat, bottom part of the dish. Hmmm, the dish is held to the case with several screws/PEM nuts that are symmetrically spaced. You can undo the dish and flip it over (you will have leave out the three screws on the front of the assembly where the dish is notched out for some nylon bushings or do some grinding on the bushings if you want those three screws to fit). The battery cells are a tiny bit too big to drop down into the dish, but (according to the Battery Expert) you can mount the cells upside down. The top of the cells will rest on the lip of the dish and the battery terminals will sit in space between the lip and bottom of the dish. There is enough space between the batteries to run the wires in the dish and up between the two middle cells to the PC board connectors. Voila, everything fits perfectly. ---------------------------------------- _________________________________________________________________ Windows Live: Keep your friends up to date with what you do online. http://windowslive.com/Campaign/SocialNetworking?ocid=PID23285::T:WLMTAGL:ON:WL:en-US:SI_SB_online:082009 From holrum at hotmail.com Sat Aug 22 00:15:29 2009 From: holrum at hotmail.com (Mark Sims) Date: Sat, 22 Aug 2009 00:15:29 +0000 Subject: [volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard? In-Reply-To: References: Message-ID: Ooops, the batteries mentioned in my last post should be PS640's, not PS604's... They do seem to work. We had a 2 hour power failure last night which the 732A sailed through just fine. ---------------------------------------- _________________________________________________________________ Windows Live: Keep your friends up to date with what you do online. http://windowslive.com/Campaign/SocialNetworking?ocid=PID23285::T:WLMTAGL:ON:WL:en-US:SI_SB_online:082009 From scottr9 at yahoo.com Wed Aug 26 13:28:56 2009 From: scottr9 at yahoo.com (Randy Scott) Date: Wed, 26 Aug 2009 06:28:56 -0700 (PDT) Subject: [volt-nuts] 3458A AC board In-Reply-To: Message-ID: <39022.28961.qm@web57701.mail.re3.yahoo.com> Okay, it arrived a few days ago. Its pretty banged up on the outside and obviously lived a pretty hard life, but it looks pristine on the inside. All of the connections look good and the voltages on the inguard power supply are fine. The only thing that I've found is what appears to be a blown fuse. There are two soldered-on fuses on the AC board: F701 seems okay (ohm meter sees a short), F702 is open (blown). Anyone have an idea what this fuse is for? There are three additional fuses (F001, F002, and F003) on the AC board near a silkscreen label "SPARE FUSES". Are these truly spares? Are there any special precautions that I should take before swapping out the bad fuse for one of the spares? Randy. --- On Tue, 8/18/09, Mark Sims wrote: > From: Mark Sims > Subject: [volt-nuts] 3458A AC board > To: volt-nuts at febo.com > Date: Tuesday, August 18, 2009, 12:47 PM > > First thing to do is get the meter in and to try and debug > the AC board.? It could be something as simple as a > flakey connection or bad cap/diode/transistor/moon phase > modulator. > > If you have a (very good) friend with another 3458A it > would be good to try swapping the AC board to verify that is > actually the problem. > > Next I would probably get the component level > documentation? try to debug the unit with that info. > > Only then would I spring for a new AC board (or probably > just let HP fix the thing).? It would not be good to > buy a $1000 board that does not fix the problem...? > _________________________________________________________________ > With Windows Live, you can organize, edit, and share your > photos. > http://www.windowslive.com/Desktop/PhotoGallery > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > From holrum at hotmail.com Wed Aug 26 15:41:36 2009 From: holrum at hotmail.com (Mark Sims) Date: Wed, 26 Aug 2009 15:41:36 +0000 Subject: [volt-nuts] 3458A AC board Message-ID: Check to see if you can see any etches going to the "spare" fuses. If, so... they ain't spare. It was fairly common for equipment of this vintage to have spare fuses, but I have never seen them soldered down. Are the spares mounted in sockets and the others soldered down?. Also when replacing pin lead/pico/wire lead fuses of fairly small amp (< 2A?) rating, I usually install pins from an old machine pin wire-wrap socket onto the circuit board. That way you can replace the fuse without having to do more soldering on the board. Many times whatever killed the fuse is a persistent fault and will kill the replacement. _________________________________________________________________ Windows Live: Keep your friends up to date with what you do online. http://windowslive.com/Campaign/SocialNetworking?ocid=PID23285::T:WLMTAGL:ON:WL:en-US:SI_SB_online:082009 From gbusg at comcast.net Wed Aug 26 16:24:16 2009 From: gbusg at comcast.net (Greg Burnett) Date: Wed, 26 Aug 2009 10:24:16 -0600 Subject: [volt-nuts] 3458A AC board References: <39022.28961.qm@web57701.mail.re3.yahoo.com> Message-ID: <000d01ca2669$a8fee8a0$6501a8c0@gb02> Randy wrote: There are two soldered-on fuses on the AC board: F701 seems okay (ohm meter sees a short), F702 is open (blown). Anyone have an idea what this fuse is for? --------clip-------- Randy, F702 is a 0.125A fuse between raw -18V and the collector of Q702, which is the -17V regulator. So I'd first measure the resistance from board ground to the emitter of Q702. It it's a short (or nearly so), you'd want to follow the -17V line to see what's holding it down. First thing to look at would be the 15uF capacitor (C709) running from the emitter of Q702 to ground. F001, F002 and F003 are indeed spare fuses, so you can use one of them to replace F702. Let us know what you find. Greg From scottr9 at yahoo.com Thu Aug 27 00:46:27 2009 From: scottr9 at yahoo.com (Randy Scott) Date: Wed, 26 Aug 2009 17:46:27 -0700 (PDT) Subject: [volt-nuts] 3458A AC board In-Reply-To: <000d01ca2669$a8fee8a0$6501a8c0@gb02> Message-ID: <738965.66097.qm@web57707.mail.re3.yahoo.com> Greg, Thanks for the information. However, it was actually F701 (my bad) that was blown. Taking a chance, I jumpered it to one of the spares and it seems to be running great. It seems too easy... :) Randy. --- On Wed, 8/26/09, Greg Burnett wrote: > From: Greg Burnett > Subject: Re: [volt-nuts] 3458A AC board > To: "Discussion of precise voltage measurement" > Date: Wednesday, August 26, 2009, 11:24 AM > Randy wrote: > There are two soldered-on fuses on the AC board: F701 seems > okay (ohm meter > sees a short), F702 is open (blown).? Anyone have an > idea what this fuse is > for? > --------clip-------- > > Randy, F702 is a 0.125A fuse between raw -18V and the > collector of Q702, > which is the -17V regulator. So I'd first measure the > resistance from board > ground to the emitter of Q702. It it's a short (or nearly > so), you'd want to > follow the -17V line to see what's holding it down. First > thing to look at > would be the 15uF capacitor (C709) running from the emitter > of Q702 to > ground. > > F001, F002 and F003 are indeed spare fuses, so you can use > one of them to > replace F702. > > Let us know what you find. > > Greg > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > From gbusg at comcast.net Thu Aug 27 00:58:19 2009 From: gbusg at comcast.net (Greg Burnett) Date: Wed, 26 Aug 2009 18:58:19 -0600 Subject: [volt-nuts] 3458A AC board References: <738965.66097.qm@web57707.mail.re3.yahoo.com> Message-ID: <001901ca26b1$7868c740$6501a8c0@gb02> Good deal Randy! Out of curiosity, what displayed error code did the blown fuse cause? Greg ----- Original Message ----- From: "Randy Scott" To: "Discussion of precise voltage measurement" Sent: Wednesday, August 26, 2009 6:46 PM Subject: Re: [volt-nuts] 3458A AC board Greg, Thanks for the information. However, it was actually F701 (my bad) that was blown. Taking a chance, I jumpered it to one of the spares and it seems to be running great. It seems too easy... :) Randy. From scottr9 at yahoo.com Thu Aug 27 02:03:22 2009 From: scottr9 at yahoo.com (Randy Scott) Date: Wed, 26 Aug 2009 19:03:22 -0700 (PDT) Subject: [volt-nuts] 3458A AC board In-Reply-To: <001901ca26b1$7868c740$6501a8c0@gb02> Message-ID: <421243.17935.qm@web57701.mail.re3.yahoo.com> Error was "202 Hardware Failure - Slave Test: AC Board". Randy. --- On Wed, 8/26/09, Greg Burnett wrote: > From: Greg Burnett > Subject: Re: [volt-nuts] 3458A AC board > To: "Discussion of precise voltage measurement" > Date: Wednesday, August 26, 2009, 7:58 PM > Good deal Randy! Out of curiosity, > what displayed error code did the blown > fuse cause? > > Greg > > > ----- Original Message ----- > From: "Randy Scott" > To: "Discussion of precise voltage measurement" > Sent: Wednesday, August 26, 2009 6:46 PM > Subject: Re: [volt-nuts] 3458A AC board > > > Greg, > > Thanks for the information.? However, it was actually > F701 (my bad) that was > blown.? Taking a chance, I jumpered it to one of the > spares and it seems to > be running great.? It seems too easy... :) > > Randy. > > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts at febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. >