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.
