Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Orin Eman
On Sun, Aug 24, 2014 at 1:46 PM, Don@True-Cal 
wrote:

> Randy & all,
>
> You have correctly concluded that some (maybe not all) of your measurement
> problem is thermal EMF being added or subtracted in series within your
> measurement interconnect. This thermal EMF is generated at the junction of
> dissimilar metals when accompanied with thermal gradients between the test
> lead and device terminals. You have to eliminate both the dissimilarity of
> the metal junctions as well as minimize the thermal differences. The
> terminals of the 3458A as well as the 732A are Beryllium Copper so you want
> to use the same test lead terminals. Forget the typical Tin plated lugs or
> even Gold plated as both are not Beryllium Copper and constitute dissimilar
> metals. The best solution (as usually the most expensive) is to use a set
> of
> Fluke 5440A-7005 (48") cables. I also have just as good results using the
> much more flexible Pomona 11174A (lugs end always stay connected to the
> 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable
> has the added Guard built in but be sure to also use a Guard lead with the
> Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY
> cables is usually not a good idea because the lead wire to terminal also
> constitutes just as critical of junction. The above cables use Tellurium
> Copper wire which is usually hard to find and hard to crimp properly and
> NEVER solder.
>


11058A and 11174A are discontinued at Keysight.  However, Pomona 5295 spade
to banana cables are available (5295-36 at Mouser et al) and claim that
they are designed to minimize thermal EMFs.  Datasheet is here:
http://www.mouser.com/ds/2/159/d5295_1_01-51722.pdf  Any comments on these
as an alternative?

Orin.
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Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Charles Black

Hi Randy,

You can use the NPLC command to change the A/D converter's'integration 
time. Set it to 1000 if you want full resolution. It sets the hp3458a's NMR.


Charlie


On 8/24/2014 6:04 PM, Randy Evans 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  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" 
To: "Discussion of precise voltage measurement" 
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 t

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Randy Evans
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  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" 
> To: "Discussion of precise voltage measurement" 
> 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 progr

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Randy Evans
Bill,

I am trying to figure out the MATH function without much success.  The 3458


On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold  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" 
> To: "Discussion of precise voltage measurement" 
> 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  wrote:
> >
> > > Randy:
> > >
> >

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Randy Evans
Bill,

Thanks for the MATH overview.  That could be very helpful.  I definately
will give it a try.

Randy


On Sun, Aug 24, 2014 at 2:44 PM, Bill Gold  wrote:

> Todd:
>
> I check the batteries every month per the 732A manual.  Usually I keep
> a
> few used cells from previous packs around that seem to be ok after checking
> them for capacity just like checking the battery pack.  I can usually spot
> cells going bad with that method.  If I don't have a spare set then I just
> substitute a used cell until I receive a new set.
>
> I agree with you that the cheap ones are crap.  I have used Power Sonic
> a lot with some a few EaglePicher and one set of Enersys.  The EaglePicher
> are crap so I will never use them.  EaglePicher have had a couple out of 8
> that have failed very early.  I have never tried Panasonic.  So I stick
> with
> the Power Sonic's.  I am not sure why the 12 volt ones would be better than
> the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are 3
> lead acid cells.  If one of the 6 cells in the 12 volt battery go bad then
> the whole battery has to be changed.  So you better buy good quality 12
> volt
> batteries.
>
> I just can't seem to source batteries locally easily at a reasonable
> price.  So I order them from Allied usually.
>
> Bill
>
> - Original Message -
> From: "Todd Micallef" 
> To: "Discussion of precise voltage measurement" 
> Sent: Sunday, August 24, 2014 8:13 AM
> Subject: Re: [volt-nuts] 732A and Prologix received
>
>
> > Bill,
> >
> > I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But
> yes,
> > I was mistaken. The 12V 5ah batteries are the ones that I am using in one
> > of my 732A. There is more play inside the tray with the 12v batteries by
> > several mm as compared to the 6v which only has a 2-3mm. The 12v
> conversion
> > is not difficult, but it is easier if the battery tray has already been
> > machined for the 12v batteries. The battery tabs don't line up well with
> > the existing holes and need to be widened. Two additional holes must also
> > be added.
> >
> > Sourcing the batteries locally is more of a convenience than waiting for
> > the delivery. The el-cheapo 6v batteries are a waste of money and I have
> 8
> > batteries so far to prove it. They died the first time I had a 6hr outage
> > and would not hold a charge after that.
> >
> > Todd
> >
> >
> >
> >
> > On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold  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 volt

[volt-nuts] 732A and Prologix received

2014-08-24 Thread Todd Micallef
Bill,

Thanks for the tip. Do you have an automated measurement system for the
10v inter-comparisons or do you manually log them with a spreadsheet?

I don't think the 12v are better, but it is interesting that some people
have modified them to dual batteries. I do not think there is any added
benefit unless someone happens to use a lot of those particular 12v
batteries.

So far I have two with the 6v packs and one with the 12v. I have a
fourth one waiting to be repaired once I finish my current projects.

Todd
Sent from my iPad

> On Aug 24, 2014, at 17:44, "Bill Gold" >
wrote:
>
> Todd:
>
>I check the batteries every month per the 732A manual.  Usually I keep
a
> few used cells from previous packs around that seem to be ok after
checking
> them for capacity just like checking the battery pack.  I can usually spot
> cells going bad with that method.  If I don't have a spare set then I just
> substitute a used cell until I receive a new set.
>
>I agree with you that the cheap ones are crap.  I have used Power Sonic
> a lot with some a few EaglePicher and one set of Enersys.  The EaglePicher
> are crap so I will never use them.  EaglePicher have had a couple out of 8
> that have failed very early.  I have never tried Panasonic.  So I stick
with
> the Power Sonic's.  I am not sure why the 12 volt ones would be better
than
> the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are
3
> lead acid cells.  If one of the 6 cells in the 12 volt battery go bad then
> the whole battery has to be changed.  So you better buy good quality 12
volt
> batteries.
>
>I just can't seem to source batteries locally easily at a reasonable
> price.  So I order them from Allied usually.
>
> Bill
>
> - Original Message -
> From: "Todd Micallef" >
> To: "Discussion of precise voltage measurement" >
> Sent: Sunday, August 24, 2014 8:13 AM
> Subject: Re: [volt-nuts] 732A and Prologix received
>
>
>> Bill,
>>
>> I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But
yes,
>> I was mistaken. The 12V 5ah batteries are the ones that I am using in one
>> of my 732A. There is more play inside the tray with the 12v batteries by
>> several mm as compared to the 6v which only has a 2-3mm. The 12v
> conversion
>> is not difficult, but it is easier if the battery tray has already been
>> machined for the 12v batteries. The battery tabs don't line up well with
>> the existing holes and need to be widened. Two additional holes must also
>> be added.
>>
>> Sourcing the batteries locally is more of a convenience than waiting for
>> the delivery. The el-cheapo 6v batteries are a waste of money and I have
8
>> batteries so far to prove it. They died the first time I had a 6hr outage
>> and would not hold a charge after that.
>>
>> Todd
>>
>>
>>
>>
>>> On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold > 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
> Referenc

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Bill Gold
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" 
To: "Discussion of precise voltage measurement" 
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  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 i

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Bill Gold
Todd:

I check the batteries every month per the 732A manual.  Usually I keep a
few used cells from previous packs around that seem to be ok after checking
them for capacity just like checking the battery pack.  I can usually spot
cells going bad with that method.  If I don't have a spare set then I just
substitute a used cell until I receive a new set.

I agree with you that the cheap ones are crap.  I have used Power Sonic
a lot with some a few EaglePicher and one set of Enersys.  The EaglePicher
are crap so I will never use them.  EaglePicher have had a couple out of 8
that have failed very early.  I have never tried Panasonic.  So I stick with
the Power Sonic's.  I am not sure why the 12 volt ones would be better than
the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are 3
lead acid cells.  If one of the 6 cells in the 12 volt battery go bad then
the whole battery has to be changed.  So you better buy good quality 12 volt
batteries.

I just can't seem to source batteries locally easily at a reasonable
price.  So I order them from Allied usually.

Bill

- Original Message - 
From: "Todd Micallef" 
To: "Discussion of precise voltage measurement" 
Sent: Sunday, August 24, 2014 8:13 AM
Subject: Re: [volt-nuts] 732A and Prologix received


> Bill,
>
> I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes,
> I was mistaken. The 12V 5ah batteries are the ones that I am using in one
> of my 732A. There is more play inside the tray with the 12v batteries by
> several mm as compared to the 6v which only has a 2-3mm. The 12v
conversion
> is not difficult, but it is easier if the battery tray has already been
> machined for the 12v batteries. The battery tabs don't line up well with
> the existing holes and need to be widened. Two additional holes must also
> be added.
>
> Sourcing the batteries locally is more of a convenience than waiting for
> the delivery. The el-cheapo 6v batteries are a waste of money and I have 8
> batteries so far to prove it. They died the first time I had a 6hr outage
> and would not hold a charge after that.
>
> Todd
>
>
>
>
> On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold  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 ar

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Don@True-Cal
Randy & all,

You have correctly concluded that some (maybe not all) of your measurement
problem is thermal EMF being added or subtracted in series within your
measurement interconnect. This thermal EMF is generated at the junction of
dissimilar metals when accompanied with thermal gradients between the test
lead and device terminals. You have to eliminate both the dissimilarity of
the metal junctions as well as minimize the thermal differences. The
terminals of the 3458A as well as the 732A are Beryllium Copper so you want
to use the same test lead terminals. Forget the typical Tin plated lugs or
even Gold plated as both are not Beryllium Copper and constitute dissimilar
metals. The best solution (as usually the most expensive) is to use a set of
Fluke 5440A-7005 (48") cables. I also have just as good results using the
much more flexible Pomona 11174A (lugs end always stay connected to the
732A) or 11058A with more convenient shielded banana plugs. The Fluke cable
has the added Guard built in but be sure to also use a Guard lead with the
Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY
cables is usually not a good idea because the lead wire to terminal also
constitutes just as critical of junction. The above cables use Tellurium
Copper wire which is usually hard to find and hard to crimp properly and
NEVER solder.

As you observed, merely the friction of plugging in the spring banana plug
and heat transfer from your fingers will require ~3-5 minutes to stabilize.
Low mass terminals help with the time to initially stabilize but is not best
if dealing with local air current drafts that upset the instantaneous
thermal gradients between the higher mass device terminal and the lower mass
lead terminal. This issue is a trade-off and is specifically considered in
the Fluke cables but being careful with localized drafts around the
terminals during critical measurements can virtually eliminate this error
source.

I have attached an ~30-hour measurement run that I consistently do that
should give you some idea of expected measurement drift over time. Virtually
all of the measurement drift is due to the 3458A internal temperature
differences around the 7V reference caused by ambient temperature change.
The drift associated with the 732A is probably about 2-magnitudes less at
this ambient temp drift. In my situation, the inferred ambient temperature
is cycling with the home air-conditioning. Note the initial calibration
temperatures as well as the ACal temperatures and where the 3458A is
measuring exactly 10V. My primary 732A has been powered without loss for 4
years and >5 years before that. The 3458A is Agilent (Loveland) Cal'ed
yearly and is powered 24-7-365 except for the occasional mains power loss.
The graphical measurements is using a homegrown Agilent VEE program.

Don Johnson

-Original Message-
From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On
Behalf Of Randy Evans
Sent: Sunday, August 24, 2014 9:22 AM
To: Discussion of precise voltage measurement
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  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.

Re: [volt-nuts] Looking for Datron 4000 series calibration key!

2014-08-24 Thread Poul-Henning Kamp

In message 
, Todd Micallef writes:

Please notice that when you read the HP3458A over GPIB you get a
slightly higher precision due to more decimals being presented,
than you do on the display.

If you are measuring down near the noise-limit, this matters.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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and follow the instructions there.

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Charles Black

Bill,

I have never been able to use banana plugs of any kind, with my 3458A, 
due to their excessive thermal mass. I use 24 gauge wires to make a 
twisted pair by hand with no connectors for precision voltage work. As 
brought out in an earlier post by acbern, it doesn't matter about 
plating or solder at least as long as your twisted pairs are made from 
the same wire so the thermocouples balance out.


I am a big fan of M27500 shielded twisted pair wire for everyday use. It 
is durable, heat resistant and capable of very low voltage use. The 
insulator is Tefzel and the plating used to be silver but may be 
something else now.  It take a few minutes work for proper termination 
but it can be done for free. I tend to use a lot of the 24 gauge M27500 
STP wire since it is fast to come to temperature, flexible and durable 
enough to last quite awhile.
eBay always has quite a few small lengths available and Sierra Nevada 
Products has a bunch of it. Sierra Nevada Products says that it is 
Teflon but I think it may be Tefzel. I can help with termination 
instructions if wanted.


Charlie

On 8/24/2014 7:22 AM, Randy Evans wrote:

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  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 expe

Re: [volt-nuts] Looking for Datron 4000 series calibration key!

2014-08-24 Thread Todd Micallef
Chris,

Where do you live? I just had some keys made last week for my Datron units.
The first set fit my 4000A and 1071, but they did not fit my 4700. The
4000A key looked more like the pictures online, but the 4700 was completely
different.
Someone may have rekeyed or damaged the lock on the 4700. I ended up
putting the 1071 tumbler in my 4700. The original one will eventually end
up in the 1071.

Removing the 4000 switch should not be too bad. On my 4700, I have four
philips screws in the back corners. I also have three that go across the
top. One of them is behind the filter cover. I pulled the back cover away
from the frame enough to get to the switch. The switch is held to the back
cover by its outer collar. It threads on the lock and can be loosened with
some soft jaw pliers. If you can get it out, any good locksmith can make
you a set in a day.


Todd


On Sun, Aug 24, 2014 at 11:39 AM, Chris  wrote:

> Would anyone have a spare key I could purchase? I understand that you can
> simple bypass the key with a shorting switch, but I am trying to keep my
> setup looking as authentic as possible. Thanks!
> ___
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>
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[volt-nuts] Looking for Datron 4000 series calibration key!

2014-08-24 Thread Chris
Would anyone have a spare key I could purchase? I understand that you can
simple bypass the key with a shorting switch, but I am trying to keep my
setup looking as authentic as possible. Thanks!
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and follow the instructions there.


Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Todd Micallef
Bill,

I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes,
I was mistaken. The 12V 5ah batteries are the ones that I am using in one
of my 732A. There is more play inside the tray with the 12v batteries by
several mm as compared to the 6v which only has a 2-3mm. The 12v conversion
is not difficult, but it is easier if the battery tray has already been
machined for the 12v batteries. The battery tabs don't line up well with
the existing holes and need to be widened. Two additional holes must also
be added.

Sourcing the batteries locally is more of a convenience than waiting for
the delivery. The el-cheapo 6v batteries are a waste of money and I have 8
batteries so far to prove it. They died the first time I had a 6hr outage
and would not hold a charge after that.

Todd




On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold  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" 
> To: "Discussion of precise voltage measurement" 
> 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 

Re: [volt-nuts] 732A and Prologix received

2014-08-24 Thread Randy Evans
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  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" 
> To: "Discussion o