I forgot to mention that I reduced the number of measurements to 100 per set since I wasn't seeing much difference in the variance between 100 and 1000 measurements and the 1000 measurement per set takes too long.
Randy On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans <randyevans2...@gmail.com> wrote: > I am doing multiple 100 measurements simply to characterize the stability > of the 3458A and 732A units I just bought. After about 10 measurement sets > over 2 days I am seeing a variance of about .5 uV for the 10V output, or > 0.05 ppm. However, the mean varies over a range of 10 uV, or 1 ppm. Does > that sound reasonable/ > > Randy > > > On Tue, Aug 26, 2014 at 5:41 PM, <acb...@gmx.de> wrote: > >> hi randy, >> >> just for curiosity, why doing 100 measurements at nplc 1000. is this to >> sample a changing value? >> when i am doing 10 measurements from a stable signal at nplc 100 (only >> there many subsequent measuremnts with statistics make sense) I am already >> getting a stanard deviation below 0.1ppm. >> in a 30 minute test cycle, i would also be concerned about drifts (acal) >> unless the amb. temperature is really very stable (half a degree already >> adds about 0.25ppm at 10v) >> >> thanks >> >> >> >> >> > Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr >> > Von: "Randy Evans" <randyevans2...@gmail.com> >> > An: "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> > Betreff: Re: [volt-nuts] 732A and Prologix received >> > >> > Is there any way to tell when the function key routine is complete? In >> the >> > case of taking multiple readings using the DEFKEY and MATH function, I >> > don't see any indication when the routine is complete. In one >> particular >> > case, I am taking a 100 readings with NLPC set for 1000 so its a long >> while >> > before it's complete, but i have to guess when it's done. >> > >> > Thanks, >> > >> > Randy >> > >> > >> > On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans <randyevans2...@gmail.com> >> > wrote: >> > >> > > Bill, >> > > >> > > I am trying to figure out the MATH function without much success. I >> input >> > > the sequence you said (I looked up the instructions to understand >> what you >> > > did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG >> 4;TRIG; and >> > > it shows up on the display when I input BLUE F1. I hit ENTER and it >> takes >> > > the 40 measurements and the MATH symbol shows on the display during >> the >> > > measurements. After the SMPL symbol no longer blinks I hit MATH 2 >> and I >> > > get a MATH ERR symbol on the display. I tried it a couple of times >> and the >> > > same result so I am doing something wrong. Is there a better source >> for >> > > explaining how to do front panel masurements than the User Guide, >> which >> > > seems oriented at programming automatic rather than manual >> measurements. >> > > >> > > Randy >> > > >> > > >> > > >> > > On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold <wpgold3...@att.net> >> wrote: >> > > >> > >> Randy: >> > >> >> > >> The MATH function is accessible from the keypad. I don't have >> an IEEE >> > >> interface right now that works. You can also program the numeric >> keypad >> > >> keys to have preprogrammed functions. DEFKEY >> > >> >> > >> I have made my own "low thermal" measurement leads from Pomona >> #4892 >> > >> banana plugs and Belden #9272 wire. Why 9272, because it was handy >> at the >> > >> time. It is tin plated copper, shielded twisted pair 20 ga. I have >> plans >> > >> to do custom cables with 16 ga. bare copper wire that I will twist >> and >> > >> then >> > >> put a braided shield over it. I simply cannot find what I want so I >> will >> > >> build my own cable. I have done something like this before and it >> worked >> > >> fine. When I get a "round toit". >> > >> >> > >> I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I >> have >> > >> used >> > >> in the past to verify my homemade "low thermal" leads as described >> above. >> > >> Frankly I cannot see any difference between using the 1756 cables >> and my >> > >> homemade cables once I give them a few minutes for the thermals to go >> > >> away. >> > >> As far as I can tell and measure the differences, if any, are below >> 0.1 >> > >> ppm >> > >> at 10 volts. >> > >> >> > >> Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A >> are all >> > >> adjustable you may be seeing a misadjusted 1 volt from the 732A. As >> far >> > >> as >> > >> the instability of the readings it is hard to determine which is >> causing >> > >> the >> > >> problem. I have programed (DEFKEY) a numeric keypad key #1 with the >> > >> following code. "MATH 14;NRDGS 40;TRIG 4;TRIG ;" So what this >> does is >> > >> set >> > >> the MATH to "Statistics" (store high reading/low reading/ and mean >> of the >> > >> readings) in the registers, the number of readings to "40", the >> trigger to >> > >> "hold" (which keeps the meter from triggering until I press "ENTER" >> and >> > >> then >> > >> trigger the sequence of 40 readings when I push the "ENTER" button. >> You >> > >> can >> > >> do all of this manually from the keypads but since I use this >> sequence a >> > >> lot >> > >> I have preprogrammed it. This is after I set digits to "8" and PLC >> to >> > >> 100. >> > >> Once those 40 readings are finished then you can access the various >> MATH >> > >> statistic registers, using the menu, by entering "MATH" and then a 2 >> for >> > >> low, a 4 for mean, and 13 for high. Of course you could do all of >> this >> > >> through the IEEE also. The 3458A has a very rich set of measurement >> > >> commands. I am still learning all of them. It depends upon what I >> am >> > >> trying to accomplish. >> > >> >> > >> Since the 1.018 and 1.0 volt outputs are passive and derived from >> > >> resistive dividers from the 10 volt, I don't see how they could >> contribute >> > >> to the varying readings you are measuring. I think I would put a >> short on >> > >> the input of the 3458A and manually set the range to 1 volt and then >> > >> observe >> > >> the variations that way without the 732A involved. When I do this I >> see a >> > >> variation from low reading to high reading of 0.125 uVolts and then >> > >> another >> > >> 40 I get 0.155 uVolts. This is without the GUARD connected to the >> low >> > >> side >> > >> of the measurment terminals, GUARD connected doesn't seem to affect >> the >> > >> readings. So that is the base noise of the 3458A without the 732A, >> > >> somewhere below .2uVolts. When hooked up to the 732A 1.0 volt >> output I >> > >> got >> > >> a variation of 0.159 uVolts using the same 40 reading method above. >> I >> > >> would >> > >> use this to determine where your problem might exist. Just having >> the >> > >> meter >> > >> input shorted will point you in the right direction. Meter, cables >> or >> > >> 732A. >> > >> >> > >> Sorry for the long dissertation. Friends get mad at me for >> being so >> > >> detailed sometimes. >> > >> >> > >> Bill >> > >> >> > >> ----- Original Message ----- >> > >> From: "Randy Evans" <randyevans2...@gmail.com> >> > >> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> > >> Sent: Sunday, August 24, 2014 7:22 AM >> > >> Subject: Re: [volt-nuts] 732A and Prologix received >> > >> >> > >> >> > >> > Bill, >> > >> > >> > >> > I have convinced myself that the problem I an seeing is due to >> thermals. >> > >> > If I move the cables (with gold-plated banana plugs) using a small >> > >> towel >> > >> > rather than letting my hand touch the plugs, it is much more >> stable. >> > >> If I >> > >> > then hold the banana plug with my hand after the reading has >> stabilized, >> > >> > the reading drifts rapidly upward. I am trying to check the >> stability >> > >> of >> > >> > the reading but I haven't figured out the MATH function yet. I >> assume >> > >> this >> > >> > is a programmed function using GPIB only? >> > >> > >> > >> > The stability I am seeing by manually recording readings (using >> NLPC of >> > >> 100 >> > >> > and 1000) is much greater than what you are measuring on your >> system. >> > >> Not >> > >> > sure how to ascertain if it's the 3458A or the 732. The value of >> the >> > >> > readings are very different between the two - the 3458 reads about >> 50 uV >> > >> > high on the 10 V output and about 12 uV low on the 1V output. >> Rather >> > >> large >> > >> > differences (this is after an ACAL). I need to find some better >> cables >> > >> to >> > >> > make sure the errors are not due to thermals again. >> > >> > >> > >> > Randy >> > >> > >> > >> > >> > >> > On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold <wpgold3...@att.net> >> wrote: >> > >> > >> > >> > > Randy: >> > >> > > >> > >> > > I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they >> will fit >> > >> > > perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic >> LC-R064R5C and >> > >> > > others >> > >> > > that are in this size and package. Order from one of the usual >> > >> electronics >> > >> > > distributors like Allied, Mouser, Digikey. This is a very common >> > >> battery >> > >> > > as >> > >> > > it is used in a lot of "EXIT" signs so they are lighted when the >> power >> > >> goes >> > >> > > out. I don't see how the 12V 7AH will fit as they are too >> large. I >> > >> guess >> > >> > > you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 >> volt >> > >> 4 >> > >> AH >> > >> > > but the terminals are in the wrong place so you will have to >> "nibble" >> > >> out >> > >> > > the aluminum plate that holds them in the 732A battery pack. >> You have >> > >> to >> > >> > > be >> > >> > > careful if you use the 12v 5AH as you will have 4 extra battery >> > >> connection >> > >> > > leads to deal with and connect correctly. I would stick with >> the 6V >> > >> 4AH. >> > >> > > New batteries will last around 12 to 14 hours before the "CAL" >> light >> > >> goes >> > >> > > out when AC power is not applied. So shipping to Cal Lab can be >> a >> > >> problem >> > >> > > if it is a distance away, or you have to use a shipper like UPS >> or >> > >> FEDEX >> > >> > > and >> > >> > > you ship the night before and then use their "Morning delivery" >> and >> > >> the >> > >> Cal >> > >> > > Lab is expecting your 732A. Same on the way back to you. Of >> course >> > >> you >> > >> > > could always strap another battery on the 732A and hook it up to >> the >> > >> "ext >> > >> > > power" plug to last longer. I have seen it done. The issue is >> to get >> > >> the >> > >> > > Cal Lab to charge the extra battery before they ship the 732A >> back to >> > >> you. >> > >> > > >> > >> > > When you remove and work on the battery pack always have the >> AC >> > >> power >> > >> > > plugged in. The "CAL" led will stay on because the 18.6 v >> regulated >> > >> supply >> > >> > > is working. >> > >> > > >> > >> > > The "CAL" light is to indicate that power has not been lost >> to the >> > >> > > Reference Amp or other associated circuits. When the raw supply >> > >> (battery) >> > >> > > voltage drops below about 21 volts the "CAL" light will go out. >> Below >> > >> that >> > >> > > voltage the heater circuits will not work correctly and the 18.6 >> volt >> > >> > > regulated supply will not regulate. The requirement is that the >> > >> Reference >> > >> > > Amp be kept "alive" at all times to maintain the output voltage >> that >> > >> was >> > >> > > measured at the time of the most recent Calibration or >> Certification. >> > >> When >> > >> > > the semiconductor junctions are unbiased and cool off when power >> is >> > >> lost, >> > >> > > and then power is restored the result will be a different 10 >> volts >> > >> than >> > >> > > before the power failure. My experience is that after all of the >> > >> years >> > >> > > that >> > >> > > these units have been powered up, this won't happen and when >> power is >> > >> lost >> > >> > > and then restored, even months later, the 732A will come back to >> > >> almost >> > >> > > exactly the same 10 volts as when they lost power, usually with >> in 0.2 >> > >> PPM >> > >> > > after 24 hours of "warm up". >> > >> > > >> > >> > > What type of hookup leads are you using when measuring the 1 >> volt >> > >> > > output? What is the PLC set to? I always use 100 PLC to measure >> > >> this. >> > >> If >> > >> > > you don't have "low thermal" connection leads you can experience >> uV >> > >> changes >> > >> > > for a minute or more after plugging in the leads due to the >> "thermals" >> > >> > > generated because of the difference in temperature between the >> banana >> > >> jacks >> > >> > > on the 732A and the banana plugs of the leads. I have found >> that even >> > >> just >> > >> > > plugging in the lead will generate a thermal difference because >> of >> > >> > > difference of temps and some heating due to the physical act of >> just >> > >> > > inserting the plug because of friction between the jack and plug >> (my >> > >> theory >> > >> > > at any rate). You have to allow at least a minute or more before >> > >> being >> > >> > > able >> > >> > > to make a measurement after plugging in the leads. I just >> measured >> > >> the >> > >> > > variation of the 1 volt output of my 732A and using my 3458A and >> I >> > >> got a >> > >> > > total difference of 0.159 uV over 40 measurements using 100 PLC >> on >> > >> the >> > >> 1 >> > >> > > volt range of the 3458A. Using the MATH function and all of the >> data >> > >> you >> > >> > > can collect. That was after waiting for several minutes after >> > >> plugging >> > >> in >> > >> > > the leads. >> > >> > > >> > >> > > I hope all of this helps. >> > >> > > >> > >> > > Bill >> > >> > > >> > >> > > >> > >> > > >> > >> > > ----- Original Message ----- >> > >> > > From: "Randy Evans" <randyevans2...@gmail.com> >> > >> > > To: "Discussion of precise voltage measurement" < >> volt-nuts@febo.com> >> > >> > > Sent: Friday, August 22, 2014 9:03 PM >> > >> > > Subject: Re: [volt-nuts] 732A and Prologix received >> > >> > > >> > >> > > >> > >> > > > Todd, >> > >> > > > >> > >> > > > Thanks for the info. I have several Panasonic 12V 7 AH >> batteries >> > >> that >> > >> I >> > >> > > > keep topped off and they have very low current draw (~2 to 3 >> mA at >> > >> 13.5 >> > >> > > > VDC) when charged and at their float voltage, so I am pretty >> sure >> > >> they >> > >> > > are >> > >> > > > in good condition. I will look at getting those in the units >> after >> > >> I >> > >> > > > ascertain the condition of the 732. >> > >> > > > >> > >> > > > So now I have a what appears to be a functioning 3458A and a >> 732A >> > >> but >> > >> > > they >> > >> > > > slightly disagree. I am like the man with two watches that >> disagree >> > >> on >> > >> > > the >> > >> > > > time - which is correct? For the moment, i am only concerned >> with >> > >> > > > stability. The need for absolute accuracy will come later. >> > >> > > > >> > >> > > > Randy >> > >> > > > >> > >> > > > >> > >> > > > On Fri, Aug 22, 2014 at 8:06 PM, Todd Micallef < >> tmical...@gmail.com >> > >> > >> > >> > > wrote: >> > >> > > > >> > >> > > > > Randy, >> > >> > > > > >> > >> > > > > You have two possible choices. It can be configured with 4 x >> 6v >> > >> 4Ah >> > >> > > > > batteries or 2 x 12v 7Ah batteries. Hopefully the previous >> owner >> > >> has >> > >> > > > > modified the battery pack already. A couple of mine needed a >> > >> nibbler >> > >> > > tool >> > >> > > > > to remove enough of the aluminum cover that fits over the >> tops of >> > >> the >> > >> > > > > batteries. The original cover will short out to the battery >> tabs >> > >> > > regardless >> > >> > > > > of the battery configuration if this is not done. >> > >> > > > > >> > >> > > > > You can find larger capacity batteries that will give you >> slightly >> > >> more >> > >> > > > > battery life. I lost a couple sets of mail-order batteries >> after a >> > >> few >> > >> > > > > extended outages. I would recommend going with locally bought >> > >> batteries >> > >> > > > > instead of the cheaper mail order. My local Batteries Plus >> will >> > >> > > typically >> > >> > > > > have some warranty if I remember correctly. Moving forward I >> will >> > >> only >> > >> > > use >> > >> > > > > 2 12v batteries and pre-charge them on a battery charger to >> > >> equalize >> > >> > > them >> > >> > > > > before putting them in the 732A. I think the cheap batteries >> did >> > >> not >> > >> > > > > discharge equally, and would not recover when power was >> applied. >> > >> > > > > >> > >> > > > > Inspect the back plane for damaged traces and look at the >> > >> capacitors. I >> > >> > > had >> > >> > > > > a few that looked questionable. So far, I have replaced all >> the >> > >> big >> > >> > > caps >> > >> > > on >> > >> > > > > the pre-regulator and regulator boards. My feeling is that >> once >> > >> these >> > >> > > go >> > >> > > > > online, they should run as long as possible between repairs. >> > >> > > > > >> > >> > > > > The battery charger circuit may need adjusting. I tweaked >> mine and >> > >> it >> > >> > > > > seemed to work fine. >> > >> > > > > >> > >> > > > > Todd >> > >> > > > > >> > >> > > > > >> > >> > > > > On Fri, Aug 22, 2014 at 10:42 PM, Randy Evans < >> > >> > > randyevans2...@gmail.com> >> > >> > > > > wrote: >> > >> > > > > >> > >> > > > > > I received my Fluke 732A today. Just powered it up but it >> needs >> > >> new >> > >> > > > > > batteries. Any suggestions for sources (I haven't opened >> up the >> > >> unit >> > >> > > > > yet - >> > >> > > > > > I want to make sure it works before doing that). Also >> received >> > >> the >> > >> > > > > > ProLogix USB-GPIB adapter. I plan on using Mark Sims' CAL >> ran >> > >> data >> > >> > > > > dumper >> > >> > > > > > program to get the CAL data from my 3458A. Should be a >> busy >> > >> weekend. >> > >> > > > > > >> > >> > > > > > Randy >> > >> > > > > > _______________________________________________ >> > >> > > > > > volt-nuts mailing list -- volt-nuts@febo.com >> > >> > > > > > To unsubscribe, go to >> > >> > > > > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > >> > > > > > and follow the instructions there. >> > >> > > > > > >> > >> > > > > _______________________________________________ >> > >> > > > > volt-nuts mailing list -- volt-nuts@febo.com >> > >> > > > > To unsubscribe, go to >> > >> > > > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > >> > > > > and follow the instructions there. >> > >> > > > > >> > >> > > > _______________________________________________ >> > >> > > > volt-nuts mailing list -- volt-nuts@febo.com >> > >> > > > To unsubscribe, go to >> > >> > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > >> > > > and follow the instructions there. >> > >> > > >> > >> > > _______________________________________________ >> > >> > > volt-nuts mailing list -- volt-nuts@febo.com >> > >> > > To unsubscribe, go to >> > >> > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > >> > > and follow the instructions there. >> > >> > > >> > >> > _______________________________________________ >> > >> > volt-nuts mailing list -- volt-nuts@febo.com >> > >> > To unsubscribe, go to >> > >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > >> > and follow the instructions there. >> > >> >> > >> _______________________________________________ >> > >> volt-nuts mailing list -- volt-nuts@febo.com >> > >> To unsubscribe, go to >> > >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > >> and follow the instructions there. >> > >> >> > > >> > > >> > _______________________________________________ >> > volt-nuts mailing list -- volt-nuts@febo.com >> > To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> > and follow the instructions there. >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> > > _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
