[volt-nuts] 732A and Prologix received

Randy Evans randyevans2688 at gmail.com
Wed Aug 27 08:36:00 EDT 2014 

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 <randyevans2688 at 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, <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
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>> > >> > > > > > and follow the instructions there.
>> > >> > > > > >
>> > >> > > > > _______________________________________________
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