[volt-nuts] 732A and Prologix received

Randy Evans randyevans2688 at gmail.com
Wed Aug 27 08:13:25 EDT 2014 

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, <acbern at 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" <randyevans2688 at gmail.com>
> > An: "Discussion of precise voltage measurement" <volt-nuts at 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 <randyevans2688 at 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 <wpgold3637 at 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" <randyevans2688 at gmail.com>
> > >> To: "Discussion of precise voltage measurement" <volt-nuts at 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 <wpgold3637 at 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" <randyevans2688 at gmail.com>
> > >> > > To: "Discussion of precise voltage measurement" <
> volt-nuts at 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 <
> tmicallef at 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 <
> > >> > > randyevans2688 at 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 at febo.com
> > >> > > > > > To unsubscribe, go to
> > >> > > > > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> > >> > > > > > and follow the instructions there.
> > >> > > > > >
> > >> > > > > _______________________________________________
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> > >> > > > >
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