[volt-nuts] 732A and Prologix received
Randy Evans
randyevans2688 at gmail.com
Tue Aug 26 00:23:18 EDT 2014
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
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>> > > > > > and follow the instructions there.
>> > > > > >
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