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.
