Re: [volt-nuts] Fluke 732A schematic re-drawn?

[Bill Gold]

David:

I will be guessing that you are discussing the lack of Q14 that is
chassis mounted on some versions of A4, driven by Q13.

I have sent you by PM a pdf of a 732A manual that I probably got from
FLUKE.
If you look at the schematic for A4 this one has the chassis mounted Q14
shown and listed in the parts list for A4.

The interesting thing here is that a manual I sent you is P/N
645051 dated May 1983, while another manual P/N 788414 dated
May 1986 does NOT show Q14.
So for some reason known only to the people at FLUKE Q14 must have been
dropped by May 1986.  Go figure.

I don't have any other manuals except those two P/Ns.  The best I can
figure out at this time is that Q14 was dropped between A4 Rev A and A4 Rev
D.  According to the parts list in the May 1986 manual Q13 is a 2N3906.  The
Ic maximum is 200 ma.  I know that the overall current draw from the
batteries when no AC power applied is about 250ma, but I don't know how much
of that is for the heaters.

Bill


- Original Message - 
From: "David C. Partridge" 
To: "'Discussion of precise voltage measurement'" 
Sent: Friday, January 19, 2018 4:16 AM
Subject: [volt-nuts] Fluke 732A schematic re-drawn?


> The schematic for the A5 Reference and Oven Controller Board has to be one
> of the worst schematics I've seen in a while, breaking pretty much all the
> rules on making a schematic understandable.  I suspect this was done
> deliberately.
>
> Has anyone ever re-drafted this (to include the A4 pass transistor
> components) to make sense of it?
>
> May your volt always be stable
> Dave
>
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Re: [volt-nuts] Get 10K resistor calibrated in UK

[Bill Gold]

Frans:

Mine which was built in 1979, and corrected for the 1990 change in the ohm,
and calibrated last in 2009 has drifted upwards by 1.61 ppm total.  So about
0.054 ppm/year.  I don't have any data from those 30 years so this is the
beginning and end points.  These all seem to have a spectacular performance
to say the least!

Regards
Bill

- Original Message - 
From: "Electronics and Books via volt-nuts" 
To: "Discussion of precise voltage measurement" 
Sent: Wednesday, November 29, 2017 6:25 AM
Subject: Re: [volt-nuts] Get 10K resistor calibrated in UK


> can anyone tell me howmuch a SR104 10k resistor drift
>
> Met vriendelijke groeten
> Regards
> Frans
>
> electronicsandbo...@yahoo.com
> http://ElectronicsAndBooks.com
> Netherlands
>
> Discere ne cesses
>
> 
> On Wed, 11/8/17, David C. Partridge  wrote:
>
>  Subject: Re: [volt-nuts] Get 10K resistor calibrated in UK
>  To: "'Discussion of precise voltage measurement'" 
>  Date: Wednesday, November 8, 2017, 4:08 PM
>
>  I guess that depends on your
>  definition of cheap :(
>
>  Dave
>
>  -Original Message-
>  From: volt-nuts [mailto:volt-nuts-boun...@febo.com]
>  On Behalf Of Alan Ambrose
>  Sent: 08 November
>  2017 14:31
>  To: volt-nuts@febo.com
>  Subject: Re: [volt-nuts] Get 10K resistor
>  calibrated in UK
>
>  NPL i.e.
>  the UK national lab, are also surprising flexible and cheap.
>  Looking at their schedule for '15/'16 (the one I
>  happen to have to hand) they had 10K ohm cal 30-Nov-15 to
>  11-Jan-16 @ £510. They also had voltage cal October and
>  March at ~£420.
>
>  A.
>  ___
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Re: [volt-nuts] Update on 720A

[Bill Gold]

David:

I had the same problem as you when I got my used 720A years ago.  Both
the "A" and "B" decade had a few resistors that had changed over the years.
I don't think as bad as you experienced but still they would not balance
within the range of the adjustment pots.  So I "adjusted" those that needed
correcting with either parallel or series resistors as necessary.  I used
the best tolerance resistors I could get at that time.  I figured that the
"adjustment" resistors were such a small amount of the resistors I was
trying to adjust, that the TC wouldn't be much of a problem.  However I did
have to go through these "adjustments" several times as I noticed that
correcting one would then affect others in the string.  This is probably
what you are experiencing with needing to "readjust" others again.  A few
passes in each string finally got the adjustments into a good range and they
have stayed there for years now.  As far as I am concerned this is all "good
enough" for hobbyists or VoltNuts who don't want to spend $5,000 or more to
get FLUKE to refurbish your instrument, if FLUKE is even interested in doing
the job and has the parts.  Notice that some resistors in the "A" and "B"
decades are selected at the factory anyhow.  If you have the money, then be
a "purest".  It might be cheaper just to buy a new 720A.

As you realize now the 720A input resistance is 100k.  So you will get a
small voltage drop from the voltage source to the input of the 720A,
depending upon the size of the wire you are using.  Of course the proper way
to insure that there is no drop is to use Kelvin connections from the
voltage source to the input of the 720A and then set the voltage source to
external Kelvin sensing.  What I usually do is to set the ratio dials to
.99X and then set the voltage supply to get exactly 10.000 on my
3458A.  Then you have the best chance to get an idea of the accuracy of the
720A ratio at .8, .7, .6 and so on.  Don't let the 3458A autorange when down
to the 0.1 ratio!  Then to minimize the effects of the "B" decade, use
.89X, .79X down to .09X.  The only problem with this method is
that you don't get to check the .9 ratio.  So what you can do is connect the
voltage source to the "1.1" input, set the ratio dials to 1.000 and then
set the voltage source to give you 10.000 volts on the DVM.  Now you can
check the .900, .800 and so on ratios.

I am sure that I did the R203 adjustment as described in paragraph 4-25
of the manual.  It has been years now.

All IMHO of course.  You are now down into measurement "mud" so to
speak.  This is probably why the 3458A development team used the JJA at
Loveland to check the overall linearity of the 3458A A/D.  The 720A (or
equivalent) wasn't good enough at 0.1 ppm!

Bill

- Original Message - 
From: "David C. Partridge" 
To: "'Discussion of precise voltage measurement'" 
Sent: Tuesday, August 08, 2017 7:39 AM
Subject: Re: [volt-nuts] Update on 720A


> Chuck,
>
> I totally get your point that ideally you should use any KVD in
null-balance mode.  I do note however that you can load it up to 11mA
without damage though I've not once gone anywhere near that (worst case
insult has been about 0.1mA).   However it does also say that to avoid
loading errors you should load with an impedance >= 1TeraOhm (10**12).
>
> Clearly a 3458A on the 10V and lower ranges is merely > 10GOhm and will
show loading effects.
>
> So, yes, I do recognise I was "doing it wrong"!
>
> I don't believe I've inflicted any damage, and have managed to restore it
to a useable state from a fairly sorry condition:   When I got it, two oil
bath resistors were *way* off value (202 and 100 ohms low respectively), and
the S2 shunt resistors were about 1.3 ohms high which was far enough off to
prevent S2 calibration.   There were were also sundry other problems like
two open circuits in the final decade, a badly worn trim pot, and sundry
wires broken at solder joints.
>
> Ideally I'd like to replace the KVD "Bridge Balance" pot as that's a bit
noisy but shudder to think what that might cost if I could even find one.
>
> Cheers
> Dave
> -Original Message-
> From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Chuck
Harris
> Sent: 08 August 2017 13:34
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Update on 720A
>
> Hi Dave,
>
> Fundamentally, any input impedance from your 3458 is going to throw your
720A out of wack.  the 720A is not supposed to have even picoamps of
loading nothing, nada, zip.
>
> I would suggest that before you damage your 720A further, you read the
manual for the 720A and follow the instructions to the letter.  An HP3458A
is not a substitute for a null detector and a voltage calibrator.
>
> The calibration of a 720A requires that no current, none, zip, be drawn
from the 720A on any port.  It can only be done by using a voltage

Re: [volt-nuts] Update on 720A

[Bill Gold]

David:

Ignore my previous post.  In thinking about this while out shopping this
morning I know the answer.

The output resistance of the 720A is about 66k ohms.  Your voltmeter has
an input resistance of 10 megohms.  You are simply loading the output of the
720A.  The reason that the 0.1 ratio has about the expected voltage is
because the 10 Volt range your voltmeter probably has a very high input
resistance.  You are on "autorange" and when the output is set for 0.2 ratio
the voltmeter is now on the 20 volt range which is now 10 megohms.

I get the same results as you do when measuring 0.9 ratio on my setup.
89.920 volts.  Check your 720A by applying 10 volts and then do your ratio
checks on the first decade.

I just haven't used a 720A for a while and I didn't remember about the
output resistance.  When you get to become a "well aged citizen" it takes a
while to recall things.

Bill


- Original Message - 
From: "David C. Partridge" 
To: "'Discussion of precise voltage measurement'" 
Sent: Monday, August 07, 2017 1:49 AM
Subject: [volt-nuts] Update on 720A


> I've added resistors in series with R1008 and R1044 to bring the
resistance
> for those parts of the A divider to a value that it would calibrate OK
(two
> of the resistor sets in the oil bath very low in value).  I also had to
> remove five turns (about 1.3 Ohms)  from R1051 as the combined value of
R313
> and R314 was too high to allow me to calibrate S2.   I also replaced R1041
> as it was worn out (almost impossible to get a null).
>
> I've successfully calibrated the C decade as per the maintenance part of
the
> manual.
>
> Sadly the beast isn't giving me a nice linear voltage sequence when using
> just the A decade.
>
> Input voltage 100.001,4V fed to 0/1.0 Input terminals  All Decades set to
> zero except Decade A.
>
> Decade A Output V
>  0.1  9.999,88
>  0.2 19.967,8
>  0.3 29.936,7
>  0.4 39.903,8
>  0.5 49.874,7
>  0.6 59.855,6
>  0.7 69.852,4
>  0.8 79.871,3
>  0.9 89.919,6
>
> See also attached graph.
>
> Any suggestions on where to look for trouble will be most welcome ...
>
> All sections of the A decade attenuator now measure about 9.999,2 ohms.
>
> It was suggested on eevblog that the next decade (or a subsequent one) was
> loading it, but with all the other decades set to 0 I don't quite "get"
how.
>
> Thanks
> Dave
>






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Re: [volt-nuts] Update on 720A

[Bill Gold]

David:

First suggestion would be to see what the output measures, with the
input still set to 100.0014 volts (same as before), when setting the dials
to:

0.9X(equivalent to setting the "A" decade to "0.1")
1.9X(equivalent to setting the "A" decade to "0.2")
2.9X(equivalent to setting the "A" decade to "0.3")
3.9X(equivalent to setting the "A" decade to "0.4")
and so on up to
8.9X(equivalent to setting the "A" decade to "0.9")

What is the output when the dials are set to  9.9X?  It should be
100.0014 (or very, very close) just like the input voltage.

Also what do you mean by your statement "Sadly the beast isn't giving me
a nice linear voltage sequence when using
just the A decade."  Do you mean that other settings when decade B, C, D and
so on are not "0", produce ok results?

Bill


- Original Message - 
From: "David C. Partridge" 
To: "'Discussion of precise voltage measurement'" 
Sent: Monday, August 07, 2017 1:49 AM
Subject: [volt-nuts] Update on 720A


> I've added resistors in series with R1008 and R1044 to bring the
resistance
> for those parts of the A divider to a value that it would calibrate OK
(two
> of the resistor sets in the oil bath very low in value).  I also had to
> remove five turns (about 1.3 Ohms)  from R1051 as the combined value of
R313
> and R314 was too high to allow me to calibrate S2.   I also replaced R1041
> as it was worn out (almost impossible to get a null).
>
> I've successfully calibrated the C decade as per the maintenance part of
the
> manual.
>
> Sadly the beast isn't giving me a nice linear voltage sequence when using
> just the A decade.
>
> Input voltage 100.001,4V fed to 0/1.0 Input terminals  All Decades set to
> zero except Decade A.
>
> Decade A Output V
>  0.1  9.999,88
>  0.2 19.967,8
>  0.3 29.936,7
>  0.4 39.903,8
>  0.5 49.874,7
>  0.6 59.855,6
>  0.7 69.852,4
>  0.8 79.871,3
>  0.9 89.919,6
>
> See also attached graph.
>
> Any suggestions on where to look for trouble will be most welcome ...
>
> All sections of the A decade attenuator now measure about 9.999,2 ohms.
>
> It was suggested on eevblog that the next decade (or a subsequent one) was
> loading it, but with all the other decades set to 0 I don't quite "get"
how.
>
> Thanks
> Dave
>






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Re: [volt-nuts] Fluke 332B

[Bill Gold]

David:

The 332D and the 332B are identical except for the accuracy specs for
the stability of the output voltages.

332B spec for 10 Volts is +/- .002% (20 ppm) for 90 days while the 332D
spec for 10 Volts is +/- .001% (10 ppm) for 60 days.  The monthly drift
specs are also slightly better on the D than the B.

I suspect that FLUKE simply aged and selected a more stable reference
device along with matching the resistors in the sampling string for less
drift.  For all of that you paid US$2,595 for the 332B and US$2,995 for the
332D in 1973.

I seem to remember someone replacing the chopper assembly with something
a little more modern.  Don't know where I saw that.  I have a B and a D and
both seemed to be very stable with the existing chopper assembly.

One thing I did find is that the electrolitic caps have a high tendency
to go bad.  Not the big ones on the raw supply but those on the various plug
in assemblies.  I seem to remember that they were in a range of 1 ufd to 47
ufd or so.  So check them all or better yet just recap.  You will save
yourself a LOT of troubleshooting time in the long run.  There is also a
discussion of this subject either on VoltNuts or EEVBLOG.

Bill


- Original Message - 
From: "David C. Partridge" 
To: "'Discussion of precise voltage measurement'" 
Sent: Saturday, July 08, 2017 5:09 AM
Subject: [volt-nuts] Fluke 332B


> Amongst the stuff I recently acquired is a Fluke 332B (sn 4151).
>
> I found the manual for the 332D on the Fluke website, but can't find one
> specifically for the 332B apart from an incomplete US Army version.
>
> I have some questions:
>
> 1) Does anyone know where I can find the matching manual
>
> 2) If not, how useful is the 332D manual?
>
> 3) It was last calibrated in 2010, and appears to be consistently low in
> output (about 5mV at 100V, 25mV at 500V, 50mV at 1000V) after being on for
> an hour.  Is that the sort of error I should expect after that period?
>
> 4) I'm leery of the chopper amp, did anyone (Dr. Frank?) do a retrofit
using
> a modern chopper op-amp or similar?
>
>
> Thanks
> Dave
>
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Re: [volt-nuts] Initial Turn-On Fluke 332D?

[Bill Gold]

Good point.  I have found that checking all the electrolytic caps on the PC
Boards is a good idea.  Many have failed over the years and the unit will
not work properly, including oscillations on the output.  Usually they have
little or no capacitance.  I have done this step to 4 units over the years
and have found a lot of bad electrolytic caps in that time.

Bill

- Original Message - 
From: "Mark Sims" 
To: 
Sent: Saturday, November 26, 2016 10:02 AM
Subject: [volt-nuts] Initial Turn-On Fluke 332D?


> You will probably need to replace a lot of the electrolytic caps on the
circuit board...
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Re: [volt-nuts] Initial Turn-On Fluke 332D?

[Bill Gold]

Brooke:

The 332D has no internal batteries, CPU or other internal memory.
Accuracy is dependent upon the internal reference on the reference card and
the adjustments of the first 3 decade resistors, the three range resistors,
the reference resistor and the three zero range resistor adjustments.

Make sure that there are jumpers installed between the "output" and
"sense" terminals (usually two flat blade jumpers).  Turn on the 332D to
"standby/reset" and then wait for a few seconds.  You should hear a relay
click, then the switch can be set to "opr".  For intial settings set the
"range" switch to 10 V, the "readout" dials to all 0s, the meter switch to
"output voltage", the "voltage trip" switch to 10 V, turn the "vernier"
control CW to full, and the "current limit" control to about 1/2 CW or so.

Then, if everything is working, you can connect a voltmeter to the
outputs and turn up the first decade dial to a voltage.

Have fun,

Bill


  - Original Message - 
From: "Brooke Clarke" 
To: "Discussion of precise voltage measurement" 
Sent: Friday, November 25, 2016 10:46 AM
Subject: [volt-nuts] Initial Turn-On Fluke 332D?


> Hi:
>
> I just received a Fluke 332D from Fair Radio, but before I do anything is
there some initial checks or a battery that
> needs attention?
> Just started reading the manual.
>
> -- 
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> The lesser of evils is still evil.
>
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Re: [volt-nuts] Fluke DVMP Care Plan

[Bill Gold]

Ken:

I had my 732B calibrated at FLUKE in Everett WA last year.  I had the
Z540 with before and after data cal done.  The price was $695 which included
FLUKE shipping the 732B back to me, one day service.  FLUKE wanted me to
ship it to them overnight delivery by 10 AM which cost $250 UPS.  But after
that I decided that I would ship it either overnight afternoon delivery
(which is cheaper) or 2 day delivery (which is even more reasonable).
Hindsight is always better, just like Monday morning quarterbacking.

I know that my battery can last 3 days real easy by discharging it for 3
days and monitoring the battery voltage.  I think that FLUKE is just trying
to make sure that some units are not shipped with old, marginal batteries.
Then the battery would go dead and the "before" data could not be supplied
to the customer.  The one surprise was that my unit had the handle missing
and FLUKE installed a new handle and included that in the total cal cost.
The stupid handle retails for $120 and the hardware is another $27.

Bottom line here is that I don't care if the "calibration stickers" are
inplace or not when FLUKE receives the unit, so if the battery wouldn't hold
a 3 day charge I would replace it and test it before I send it in again.  I
would use the 2 day service.

The uncertainty would be how well the bank of 4 732Bs that they compared
my unit with at the Cal Lab.  But since those don't leave FLUKE and are
certified every 90 days (probably to the FLUKE JVS), according to the
certificate, my guess is that the voltage would be within .3 PPM depending
upon how much drift your unit would have during transit.  Since I have 4 ea
732As, collected over the years, and I had checked the stability before I
sent the 732B in, I was pretty sure that my 732B was very stable over 13
days, less than 0.1ppm.  When I got it back I began comparing it again to
the bank of 732As and it remained within 0.1ppm for 90 days.  But after that
it has started to drift steadly upwards around 0.7 ppm per year.  Since I
have a very good history on the bank of 732As I can see that the 732B is
most of the drift against the average of the bank.  Of course all IMHO and
the best data reductions I can make.

The final test of my data keeping would be to send the 732B again and
see if I am close to "The Volt" as defined by FLUKE.  Someday when I am
curious.

The whole turn around time was 10 days portal to portal to me.

Bill

- Original Message - 
From: "Ken Peek" 
To: "volt-nuts" 
Sent: Thursday, October 20, 2016 11:26 AM
Subject: [volt-nuts] Fluke DVMP Care Plan


> I own one 732B that needs calibration.  Fluke wants about $500 for the
> ISO-9001 calibration, but it would be about $250 EACH WAY to ship it
> to/from them with the proper insurance (so, about $1000 total).
>
> Mitch Van Ochten mentioned that the Fluke DVMP program might be a good way
> to do this.  [http://download.flukecal.com/pub/literature/2001531_A_w.pdf]
>
> Does anyone have an idea about how much this costs to calibrate just one
> 732B, and what kind of uncertainty I might expect?
>
> -Ken
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Re: [volt-nuts] fluke 731b battery pack

[Bill Gold]

Eric:

I have been using NiMH AA batteries in my 731B for at least 15 years
now.  I am sure that the specs say don't use them in a circuit designed for
NiCd but I haven't had any problems with over heating or overcharging.  You
have to do some mods to the battery mounting to get them in there but once
done you are good for a lifetime.  I have never checked to see how long the
NiMH batteries would run for but my guess would be longer than the original
NiCds.

Bill

- Original Message - 
From: "Eric Garner" 
To: "Discussion of precise voltage measurement" 
Sent: Wednesday, August 03, 2016 10:27 AM
Subject: [volt-nuts] fluke 731b battery pack


> So I managed to get one of the Fluke 731b's mentioned on the list a while
> back. It was a little more chewed up than the description in the auction
> led me to believe:
>
>
https://plus.google.com/u/0/112871219575380932919/posts/iDWyzwYYRdj?pid=6314634305601690930=112871219575380932919
>
> but it appears to be functional.
>
> The NiCd pack appears to have leaked some time in the past and was
removed,
> which is fine since I was going to replace the batteries anyway.
>
> Looking through the archives, replacement battery packs for the 731b has
> been a popular topic but I have some questions that remain open.
>
> 1. NiMH cells seem to work in the 731b so I'd prefer to use them over NiCd
> because of the higher capacity and lower toxicity of potential leaks. Is
> there a downside to doing this?
>
> 2. If I go with NiMH, is there a manufacturer that's prefered? reading
> reviews of NiMH cells online leads me to believe that some manufacturers
> (Tenergy) have lower quality and are less reliable.
>
> 3. If I go with NiCd would you expect problems if I used larger cells
(4/5A
> vs 2/3A)
>
>
>
>
> thanks
>
> --Eric
> _
> Eric Garner
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Re: [volt-nuts] “A Solid-State Reference System”. Author: John R. Pickering

[Bill Gold]

Alan:

The best information I have ever been ever to dig up on this subject is
contained in US patent #6,342,780.  I will sent this to you by PM as well as
trying to attach it to this post.

Bill

- Original Message - 
From: "Alan Ambrose" 
To: 
Sent: Wednesday, November 11, 2015 1:16 PM
Subject: [volt-nuts] “A Solid-State Reference System”. Author: John R.
Pickering


> Hi,
>
> Anyone have a copy of this paper/article?
>
> [2] “A Solid-State Reference System”. Author: John R. Pickering,
> Metron Designs Ltd., Norwich, UK.
>
> referenced in the Fluke 700 doc here:
>
> http://www.elcal.ch/files/11749-eng-01-a.pdf
>
> TIA, Alan
>
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6342780_Zener_diode_reference_voltage_st.pdf
Description: Adobe PDF document
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Re: [volt-nuts] any voltnuts in the Chicagoland area?

[Bill Gold]

Randy:

Ok so does Morgan Hill qualify?  Or is that too far away for you?  Just
kidding as usual.

Bill

- Original Message - 
From: "Randy Evans" 
To: "Discussion of precise voltage measurement" 
Sent: Thursday, October 01, 2015 8:18 AM
Subject: Re: [volt-nuts] any voltnuts in the Chicagoland area?


> I would like to know if there are any volt-nuts in the San Francisco bay
> area; e.g., San Jose area where I live.
>
> Randy Evans AE6YG
>
> On Wed, Sep 30, 2015 at 4:29 PM, Pete Lancashire 
> wrote:
>
> > Interesting idea a voltnuts location database
> > On Sep 30, 2015 12:34 PM,  wrote:
> >
> > > I am looking for fellow voltnuts in the Chicagoland area to share
> > > calibration, voltage standards, etc...
> > >
> > > This hobby can get quite expensive when the costs don't get shared...
> > >
> > > Please reply to the list or direct via e-mail...
> > >
> > > Thanks
> > > ___
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> > > and follow the instructions there.
> > >
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Re: [volt-nuts] 540b Arrival...........

[Bill Gold]

David:

Sounds like you got a good find.  Clean, batteries hold a charge and has
been updated by someone.  The lithium batteries are probably the power for
the modification that solves the problem that the Mercury Battery for the
Reference Supply being "unobtainium" anymore.  I have a pdf of the
modification including schematic.  I can send it to you by PM if you are
interested.

Bill


- Original Message - 
From: "David Garrido" 
To: 
Sent: Wednesday, September 30, 2015 6:22 AM
Subject: [volt-nuts] 540b Arrival...


> Hello All,
>
> My new to me 540b arrived last evening.  I have never used one of these so
I put it on the bench, opened it up and inspected it looking for leaks
primarily.  EVERYTHING is spotless.  Fluke factory cal stickers everywhere.
AND.after plugging her in over night, all of the batteries take a charge
and test in the middle of the BATT scale.
>
> CRAZY!
>
> All of the batteries in the 20 cell pack are individually shrink wrapped
in light blue and the two others on top are AA size lithiums.  Two of them
side-by-side.  Was this a factory mod?  All the work looks to be factory,
but who knows if the PO was just REALLY good at clean work.
>
> Anyhoo………thanks for the bandwidth.
>
> Cheers,
>
> David
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Re: [volt-nuts] Fluke 720a self calibration repair

[Bill Gold]

David:

I just looked inside my 720A at the 20 turn 5K trimpots.  They are
Bourns 3005P-502 printed on them, cermets, standard 3/4", tempco 50 ppm.  So
the replacement is available directly from stock and nothing fancy.  Mine
are date code 8412 so my unit was built somewhere in the mid '80s.  Not too
sure where the idea of a wirewound pot came from here.  They are more than a
little pricey at $13.98 ea from Allied.  Looks like you need 24 to replace
them all in the "A" and "B" decades.  So that would be $335.52 unless you
buy 25 or more at which time the price drops to $12.51 which totals $312.75.
They come in tubes of 25 each which accounts for the price drop.

Digikey is $14.35 and Mouser is $14.35.  Wow!  Expensive little devils.
On the other hand (left) Digikey shows a unit from "TT Electronics/BI
Technologies" for $1.40 ea.  Interesting.  Why such a massive difference in
price?  These are 100 ppm but as I have noted in another posting the tempco
isn't very important.  It's the resistors in the oil filled can that set the
overall stability.

Bill

- Original Message - 
From: "David Garrido" 
To: 
Sent: Saturday, September 26, 2015 5:05 AM
Subject: Re: [volt-nuts] Fluke 720a self calibration repair


> Thank you for all of the input on this folks.
>
> Does anyone have a copy of the datasheet for the original Ramo-Eltra P/N
3800P-502?
>
> The reason I ask is that the price of these parts is driven in part by the
tempco and I found info that indicated 20ppm/C on one website, but that was
not a DS, just a listing of the info.  If they can be 50ppm/C or even
100ppm/C, then the price drops exponentially.
>
> I will do whatever is necessary to maintain or (LOL) improve the 720’s
legendary performance.
>
> Cheers,
>
> David
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Re: [volt-nuts] Fluke 720a self calibration repair

[Bill Gold]

David:

Run the numbers.  Assuming that the 5K-20 turn pot R1005 is set in the
middle of it's travel (2.5K), that all of the other resistors, in series and
parallel ( R1006,R1007,R1008 and R302), that make up one step of the "A"
decade have a "0" TC, only R1005 has a maximum of +/- 100 ppm per degree C,
then the maximum change on the total resistance between step 0.9 and 1.0 of
the "A" decade would only be 0.00410 % change over the entire +/- TC of
R1005.  That is 0.00410 ppm.  The "Absolute Linearity" of the "A" decade is
specified at 0.1 ppm at +/- 1 degree C, without a temp correction chart.  Of
course all of the other resistors mentioned have a TC also, which could be +
or - to the total nominal of 10,000.  Therefore, unless I am mistaken, the
less expensive +/- 100ppm pots would work just fine and you could not
observe or measure the changes.  This is also why I didn't worry about my
"trimming" R1008, the "factory selected" resistor, slightly to get the 20
turn pots to adjust to the middle of their ranges, when necessary.

IMHO

Bill

- Original Message - 
From: "David Garrido" 
To: 
Sent: Saturday, September 26, 2015 5:05 AM
Subject: Re: [volt-nuts] Fluke 720a self calibration repair


> Thank you for all of the input on this folks.
>
> Does anyone have a copy of the datasheet for the original Ramo-Eltra P/N
3800P-502?
>
> The reason I ask is that the price of these parts is driven in part by the
tempco and I found info that indicated 20ppm/C on one website, but that was
not a DS, just a listing of the info.  If they can be 50ppm/C or even
100ppm/C, then the price drops exponentially.
>
> I will do whatever is necessary to maintain or (LOL) improve the 720’s
legendary performance.
>
> Cheers,
>
> David
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Re: [volt-nuts] Sometimes you just gotta gloat............

[Bill Gold]

David:

I don't suppose you would give us the address of this Equipment Surplus
Center of yours

I like those places where they don't have an IDEA of what they have and
what it is worth!!!

Great catch to say the least.  At least you will have something to do
for a while.

What do those PCA  interconnect cables look like?  Gold plated?
Banana, spade etc.?  Might be low thermal?

Bill



- Original Message - 
From: David Garrido d.garr...@me.com
To: volt-nuts@febo.com
Sent: Tuesday, August 18, 2015 8:59 AM
Subject: [volt-nuts] Sometimes you just gotta gloat


 Hello All,

 I have been on the lookout for a variety of different FLUKE equipment.
And today, it all came together in a wonderful way.

 I went to my favorite local Equipment Surplus Center on the hunt for an HP
6260B DC PSU.  Found one, 40 dollars. DONE!!!  Or so I thought, until I
decided to take one more quick look before leaving with my new to me DC PSU.

 While cruising around I spotted what looked like a FLUKE 7105A Calibration
System.  You know the one.all hidden back in a dark corner.  Well, sure
enough it was a 7105A with its full compliment of test gear.  335D, 845AR,
720A, 721A, and a BUNCH of interconnects.  All of the equipment looks to be
in fine shape and VERY clean.  No busted or bent posts, all knobs and
switches intact.  The best part..when I asked how much he would sell it
for he told me, “If and ONLY if you take both the HP 6260B and the 7105A, I
will give it to you for $250 cash total.”

 Needles to say, I could not get my pocket opened fast enoughout flew
the cash and the gear was even loaded into the back of my truck for me.

 It has been a VERY good morning gentleman, a very good morning indeed.

 I do have a question regarding all of the FLUKE cables that came with the
7105A:

 These are the part no’s:

 PCA-0110
 PCA-0116
 PCA-0126
 PCA-0136
 PCA-0227
 PCA-0536
 PCA-0627
 PCA-0636

 I have multiples of these and cannot seem to locate any info on these
anywhere.  I have skimmed through the manuals for all of the gear and they
seem to have no reference.  What SPECIFICALLY are these for and where would
one find the info for them and their use?

 Cheers,

 David
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Re: [volt-nuts] Test Leads

[Bill Gold]

Randy:

From my own experiences and what I have done over the years about low
thermal leads.

I have made my own leads from the Pomona #4892 double gold plated banana
plugs along with using Pomona #5406 single gold plated banana plugs, where I
needed to spread the leads futher apart than the standard 3/4 inch, such as
plugging into the Fluke 732A.  I have been using Belden #9272 shielded
twinax as my cable material only because it was available at the time to me.
It is a twisted pair of 20 ga. tin plated wires inside of a braided shield.
The purests will say that the tin plating will cause Thermals when screwed
down on the Gold plated banana plugs.  I realize that and I now have 100
feet ( 50 red, 50 black ) of Pomona #6733, which is extremely flexable
copper wire with Silicone double insulation.  I will then twist these
together and the put a shield braid over that and finally put a heat shrink
layer over the shield to make my own copper twisted pair shielded wire
which I will then attach to the #4892 or #5406 banana plugs to create a
more perfect low thermal test lead ( I hope ).  This is all when I get a
round toit of course.

In the meanwhile I have purchased 6 ea Pomona #1756-48 leads.  Frankly I
cannot measure a difference between the #1756 and the homemade leads, once I
wait about 3 minutes for all Thermals to settle down.  I also have 2 ea
Fluke P/N 738716 ( 24 inches ) and 1 ea Fluke #738724 twin shielded test
leads.  These are the Fluke 5440A-7002 Low Thermal test lead set that is
recommended by Fluke for use with 732A/B, 5440A/B and other high precision
calibrators.  They are RG-58 with Tellurium Copper conductors/ Beryllium
Copper Tip Springs.  Again I cannot see differences between all of these
cables with the best measuring equipment I have.  HP 3458A DVM and Fluke
845AB Null Detector and measuring between 732A/Bs, 5440B for nulls.

I am sure that Fluke has done extensive research on this subject.  It
may well be that measurements can be made faster using the purest approach
of pure copper and gold plated connectors.  I don't know at the present
time.

Hope this helps you in making up what you need.

Bill

- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: volt-nuts@febo.com
Sent: Tuesday, July 21, 2015 9:33 AM
Subject: [volt-nuts] Test Leads


 I recently acquired a Fluke 752A to go with my Fluke 732A and HP-3458A.
 Now I need to address the need for low thermal test leads.  Does anyone
 have any suggestions for test leads that have low thermal contributions to
 measurements?  I have looked at Pomona 1756 Low Thermal EMF Cables as a
 starting point but haven't found any other candidates.

 I have heard that old TV twin lead works well since most are stranded
 copper wire.  I have tried it between my 732A and 3458A and it seems to
 work fine but I would like to use more professional looking test leads,
 particularly with correct copper spade lugs (Pomona 2305 Low thermal EMF
 spade lug, Gold-plated?).  Any other suggestions?

 Thanks,

 Randy Evans AE6YG
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Re: [volt-nuts] HP 3456A -3 Fault

[Bill Gold]

Dave:

These things are NOTORIOUS for filter cap failures in the power
supplies.  Check both the voltages and the RIPPLE on the various power
supplies.  It is not sufficent to just check the voltages.  You must check
the ripple with an o'scope.  At least this is the first step before looking
for anything else.

Good luck,

Bill

- Original Message - 
From: David Smith w...@msn.com
To: volt-nuts@febo.com
Sent: Friday, December 26, 2014 3:34 PM
Subject: [volt-nuts] HP 3456A -3 Fault


 Hello Friends,
 I have two HP 3456A's that have the same -3 fault in the test mode.
Both DVM's started exhibiting this same fault about the same time. I've
troubleshot one of the DVM's to a failure in the Isolation Logic
Transmitter. I have no waveform at the output of A3T1.
 Before I continue with troubleshooting I thought I'd ask a question of the
group.  Is there a common mode failure of these DVM? Is there something in
particular or area that I should be looking at/for?
 It's probably coincidental that they would both fail at about the same
time with the same -3 fault.
 Your input is greatly appreciated.
 Best regards,

 Dave - W6TE
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Re: [volt-nuts] 845ab Led Mod Update

[Bill Gold]

Sorry I should have said uv where ever I said mv.  Too early in the
morning where I live in the world.

Bill

- Original Message - 
From: Bill Gold wpgold3...@att.net
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Thursday, September 25, 2014 8:10 AM
Subject: Re: [volt-nuts] 845ab Led Mod Update


 Dallas:

 I check my 845ab yesterday, S/N 4470002.  It still has the neon
 bulbs/photo resistors chopper.

 From what I can observe the Peak to Peak noise on the 1 mv range is
 about +/- 0.1 mv, or a total of around 0.2 mv.  As far as temperature
drift
 I don't know.  Never tried to measure that parameter.

 Sure would love to know if the FLUKE modification to the 845ab made in
 1993, when the new circuit was put into production, makes the noise lower.
 Or better, if your efforts can make the noise lower on the 1 mv range.

 Bill
 - Original Message - 
 From: Dallas Smith dosm...@outlook.com
 To: Discussion of precise voltage measurement volt-nuts@febo.com
 Sent: Wednesday, September 24, 2014 12:06 PM
 Subject: [volt-nuts] 845ab Led Mod Update


  Well I finally got the 615nm Led's installed and the results seem so so.
  The zero drifted was significantly on the 1uV range. So I used two
  LT1634 1.25 Volt references with the current set by two 43k resistors
  from the ±15 volt supplies. The previous reference used came from the
  -0.4 volts at TP1 and +0.6 volts at TP8. Removed the 150k resistor at
  the positive end of the zero control and lifted the negative end from
  the circuit board the connected the ±1.25 ref to the zero pot. Much
  better stability, drifts by noise about  ±.1 to ±.2uv now on 1uv range.
  Is this normal now? Never used a new Fluke 845ab before. The white led's
  seemed to filter the noise better with its persistent, may go back. The
  zero seems stable with ±2 F change in room temperature now.
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Re: [volt-nuts] Old HP3458A - SN: 2823A 03939

[Bill Gold]

TIA:

Push blue key then blue R ( the shifted TRIG key) and ENTER.
Then press the downarrow V key 4 times to get to the REV? on the
display.  Then press ENTER and two numbers will be displayed with a comma
in the middle.  The first number is the multimeter's master processor
firmware revision.  The second number is the slave processor's firmware
revision.  This is if the full menu has been set.  If not, see the MENU
command in the Operator's Manual and set it to FULL.

Mine are both 7,2 and I have no problems.  The latest is 9.

Bill

- Original Message - 
From: cfo xne...@luna.dyndns.dk
To: volt-nuts@febo.com
Sent: Sunday, September 21, 2014 8:22 AM
Subject: [volt-nuts] Old HP3458A - SN: 2823A 03939


 Gents

 I'm looking for a 3458A , and have found one : SN: 2823A 03939 w. opt 002
 Seller says it's passing selftest.

 But it's an old serial# , is there any way one can verify that it has an
 up-to date firmware , and maybe via that see if it has has all the needed
 upgrades or ServiceNotes applied ?

 TIA
 CFO
 Denmark

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Re: [volt-nuts] Fluke 5200A extender board.

[Bill Gold]

Ken:

I have a 5200 extender kit including the PC Board and the cables.  In
looking at it the center PC board that has the traces on it is enclosed on
both sides with a piece of blank PC board material (no copper or traces) so
you wind up with 3 ea 0.062 PC Boards riveted together.  The center board
has the necessary traces to connect the edge connector fingers to the
socket.  The outer two boards are just plain PC material with the necessary
holes machined out so that the center board can have the connector and
fingers open.  There has been test points place on either side of the socket
so you can connect a meter or scope to the lines.

The connector has the following printing on it.   345-086-520-201
below that it has what looks like a trade mark of either a C or O with
letters inside that which I can't make out, then 3A 250V EADC ?? the ??
means I can't read this.

When you say photo copy the PC Board I will assume something that
would show how the traces are laid out on both sides.  This is impossible
without removing the 5 rivets that hold this sandwich together which I
don't want to do.

I will do a PM to you with a pdf attached of the backside of the
extender.

Bill


- Original Message - 
From: Kgoodhew kgood...@iinet.net.au
To: volt-nuts@febo.com
Sent: Wednesday, August 27, 2014 11:44 PM
Subject: [volt-nuts] Fluke 5200A extender board.


 Hi,
 The pin spacing on the card edge connectors is 0.1 (2.54 mm) and is a
43/86 dual row socket.
 I know what the extender looks like as I found one on ebay several months
ago that had already sold for $50 (damm it!!) and I have been looking ever
since, but it had a picture of it.
 It is a double sided pcb board that plugs into the female connector that
is mounted vertically in the instrument and then rises up above the top of
the instrument case where there is a female socket mounted horizontally so
in effect the board now sits horizontally above the instrument whereas
normally it sits vertically in the instrument.
 That way you have access to the board to take measurements, something you
cannot do when the boards are in the instrument due to the close spacing of
the various boards.
 As the 43/86 pin card edge connectors appear unobtainable I have sourced a
50/100 pin female connector that I can make do with, but I need either a
43/86 pin male card edge connector (which are also unobtainable) to make up
an extender using cables as you have done, so the only option appears to be
to make up a double sided pcb board with pads spaced at 0.1 centres on both
sides and then either use it to terminate the cables to the female socket ,
or probably better make the pcb the same as the original extender and just
use my 100 pin socket on that.
 That is why I was hoping someone may be able to photo copy the pcb board
if they have an extender they do not want to sell.
 Thanks,
 Ken Goodhew.



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

[Bill Gold]

Randy:

Something I had never tried to measure.  As I have found out in the past
there is a lot of overhead going on in the meter during and after a
measurement.

In thinking about this I turned OFF the autozero AZERO and the time
for each SMPL was cut in half to around the estimated 16.66 seconds for
1000 PLC.  So it becomes obvious that the meter makes an autozero
measurement for 1000 PLC and then the actual measurement for 1000 PLC which
explains the 33 seconds.  Makes sense.  This is probably why the AZERO menu
gives you ON, OFF and ONCE.  For short measurement sequences you just
autozero ONCE at the start.

Thanks for the observation, this helps me.  Everyday I learn something
new.

Bill

Thanks for the information
- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Tuesday, August 26, 2014 2:16 PM
Subject: Re: [volt-nuts] 732A and Prologix received


 Bill,

 I measured the time between SMPL symbols with NPLC set to 1000 and it is
 approximately 33 seconds. It takes an hour to complete 100 readings.

 Randy


 On Mon, Aug 25, 2014 at 10:01 PM, Bill Gold wpgold3...@att.net wrote:

  Not that I know of.  Just wait and when you don't see a SMPL on the
  display it is done.  But then with 1000 PLC that is around 16.66 seconds
  per
  reading times 100 readings is somewhere around 28 minutes and there is
  probably some overhead time so around 30 minutes.  Not from the front
panel
  at any rate.
 
  Bill
 
  - Original Message -
  From: Randy Evans randyevans2...@gmail.com
  To: Discussion of precise voltage measurement volt-nuts@febo.com
  Sent: Monday, August 25, 2014 9:23 PM
  Subject: Re: [volt-nuts] 732A and Prologix received
 
 
   Is there any way to tell when the function key routine is complete?
In
  the
   case of taking multiple readings using the DEFKEY and MATH function, I
   don't see any indication when the routine is complete.  In one
particular
   case, I am taking a 100 readings with NLPC set for 1000 so its a long
  while
   before it's complete, but i have to guess when it's done.
  
   Thanks,
  
   Randy
  
  
   On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans
randyevans2...@gmail.com
   wrote:
  
Bill,
   
I am trying to figure out the MATH function without much success.  I
  input
the sequence you said (I looked up the instructions to understand
what
  you
did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG
4;TRIG;
  and
it shows up on the display when I input BLUE F1.  I hit ENTER and it
  takes
the 40 measurements and the MATH symbol shows on the display during
the
measurements.  After the SMPL symbol no longer blinks I hit MATH 2
and
  I
get a MATH ERR symbol on the display.  I tried it a couple of times
and
  the
same result so I am doing something wrong.  Is there a better source
  for
explaining how to do front panel masurements than the User Guide,
which
seems oriented at programming automatic rather than manual
  measurements.
   
Randy
   
   
   
On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net
wrote:
   
Randy:
   
The MATH function is accessible from the keypad.  I don't have
an
  IEEE
interface right now that works.  You can also program the numeric
  keypad
keys to have preprogrammed functions.  DEFKEY
   
I have made my own low thermal measurement leads from Pomona
  #4892
banana plugs and Belden #9272 wire.  Why 9272, because it was handy
at
  the
time.  It is tin plated copper, shielded twisted pair 20 ga.  I
have
  plans
to do custom cables with 16 ga. bare copper wire that I will twist
and
then
put a braided shield over it.  I simply cannot find what I want so
I
  will
build my own cable.  I have done something like this before and it
  worked
fine.  When I get a round toit.
   
I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I
  have
used
in the past to verify my homemade low thermal leads as described
  above.
Frankly I cannot see any difference between using the 1756 cables
and
  my
homemade cables once I give them a few minutes for the thermals to
go
away.
As far as I can tell and measure the differences, if any, are below
  0.1
ppm
at 10 volts.
   
Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A
are
  all
adjustable you may be seeing a misadjusted 1 volt from the 732A.
As
  far
as
the instability of the readings it is hard to determine which is
  causing
the
problem.  I have programed (DEFKEY) a numeric keypad key #1 with
the
following code.  MATH 14;NRDGS 40;TRIG 4;TRIG ;   So what this
does
  is
set
the MATH to Statistics (store high reading/low reading/ and mean
of
  the
readings) in the registers, the number of readings to 40, the
  trigger
  to
hold (which keeps the meter from triggering until I

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

[Bill Gold]

Randy:

Sorry my fault.  You have to use the RMATH command to get the various
values stored in the registers.  See the RMATH command in the User's Guide
for a list of what registers you can read.

I sure haven't found any other guides other than the 4 manuals.  User's
Guide, Quick Reference Guide, Calibration Manual, and Assembly Level Repair.
It is just a matter of reading the guides and trying to remember what
commands are available.  It took me a lot of time to figure out what
commands I use now.  I am sure I am missing other commands that might be
useful.

Bill



- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Sunday, August 24, 2014 6:04 PM
Subject: Re: [volt-nuts] 732A and Prologix received


 Bill,

 I am trying to figure out the MATH function without much success.  I input
 the sequence you said (I looked up the instructions to understand what you
 did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG;
and
 it shows up on the display when I input BLUE F1.  I hit ENTER and it takes
 the 40 measurements and the MATH symbol shows on the display during the
 measurements.  After the SMPL symbol no longer blinks I hit MATH 2 and I
 get a MATH ERR symbol on the display.  I tried it a couple of times and
the
 same result so I am doing something wrong.  Is there a better source for
 explaining how to do front panel masurements than the User Guide, which
 seems oriented at programming automatic rather than manual measurements.

 Randy



 On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote:

  Randy:
 
  The MATH function is accessible from the keypad.  I don't have an
IEEE
  interface right now that works.  You can also program the numeric keypad
  keys to have preprogrammed functions.  DEFKEY
 
  I have made my own low thermal measurement leads from Pomona #4892
  banana plugs and Belden #9272 wire.  Why 9272, because it was handy at
the
  time.  It is tin plated copper, shielded twisted pair 20 ga.  I have
plans
  to do custom cables with 16 ga. bare copper wire that I will twist and
then
  put a braided shield over it.  I simply cannot find what I want so I
will
  build my own cable.  I have done something like this before and it
worked
  fine.  When I get a round toit.
 
  I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have
  used
  in the past to verify my homemade low thermal leads as described
above.
  Frankly I cannot see any difference between using the 1756 cables and my
  homemade cables once I give them a few minutes for the thermals to go
away.
  As far as I can tell and measure the differences, if any, are below 0.1
ppm
  at 10 volts.
 
  Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are
all
  adjustable you may be seeing a misadjusted 1 volt from the 732A.  As far
as
  the instability of the readings it is hard to determine which is causing
  the
  problem.  I have programed (DEFKEY) a numeric keypad key #1 with the
  following code.  MATH 14;NRDGS 40;TRIG 4;TRIG ;   So what this does is
  set
  the MATH to Statistics (store high reading/low reading/ and mean of
the
  readings) in the registers, the number of readings to 40, the trigger
to
  hold (which keeps the meter from triggering until I press ENTER and
  then
  trigger the sequence of 40 readings when I push the ENTER button.  You
  can
  do all of this manually from the keypads but since I use this sequence a
  lot
  I have preprogrammed it.  This is after I set digits to 8 and PLC to
100.
  Once those 40 readings are finished then you can access the various MATH
  statistic registers, using the menu, by entering MATH and then a 2 for
  low, a 4 for mean, and 13 for high.  Of course you could do all of this
  through the IEEE also.  The 3458A has a very rich set of measurement
  commands.  I am still learning all of them.  It depends upon what I am
  trying to accomplish.
 
  Since the 1.018 and 1.0 volt outputs are passive and derived from
  resistive dividers from the 10 volt, I don't see how they could
contribute
  to the varying readings you are measuring.  I think I would put a short
on
  the input of the 3458A and manually set the range to 1 volt and then
  observe
  the variations that way without the 732A involved.  When I do this I see
a
  variation from low reading to high reading of 0.125 uVolts and then
another
  40 I get 0.155 uVolts.  This is without the GUARD connected to the low
side
  of the measurment terminals, GUARD connected doesn't seem to affect the
  readings.  So that is the base noise of the 3458A without the 732A,
  somewhere below .2uVolts.  When hooked up to the 732A 1.0 volt output I
got
  a variation of 0.159 uVolts using the same 40 reading method above.  I
  would
  use this to determine where your problem might exist.  Just having the
  meter
  input shorted will point you in the right direction.  Meter, cables

Re: [volt-nuts] Access to Volt-Nuts Web site

[Bill Gold]

Randy:

It doesn't work for me either.  Same error message.  Must be down for
some reason.  Time-Nuts is down also.

Bill

- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: volt-nuts@febo.com
Sent: Monday, August 25, 2014 7:28 AM
Subject: [volt-nuts] Access to Volt-Nuts Web site


 For some reason I can no longer access the Volt-Nuts web site.  Has
 anything changed on the permissions list?  Is anyone else having this
 problem?  I get the following message:

 You don't have permission to access /pipermail/volt-nuts/ on this
server.

 Thanks,

 Randy
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Re: [volt-nuts] AC calibration

[Bill Gold]

There is one more thing that enters into this discussion and that is
reversal errors on the DC.  The complicates the transfer somewhat.  AC is
always going + and -.  DC is in one direction so you have to then
reverse the voltage to the Thermal Transfer Standard and then take the
average of the two readings.  That is why there is a Reversal switch on
the 540B.  When you are using a fixed voltage High Frequency Thermal
Converter you need an external DC reversal switch in addition to other
equipment.  You also need an AC/DC transfer switch so that you don't have to
disconnect the AC source and then hook up the DC source manually.  See the
540B again.

All Thermal Transfer Standards have some reversal error.  This is
controlled by the internal construction of the unit and exactly where the
glass isolation bead is located on the heating element.  The thermocouple
converter used in the 540B is selected to have a very low reversal error,
but always will have some error.  The error is fixed so you can approximate
a DC measurement once you have characterized the particular converter.  I
can't remember now but I think there can be up to around .05% reversal
errors on some converters, while the ones selected for the 540B are under
.01%.

Read the FLUKE Calibration: Philosophy in Practice for further
information.

Bill

- Original Message - 
From: Dave M dgmin...@mediacombb.net
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Monday, August 25, 2014 11:38 AM
Subject: Re: [volt-nuts] AC calibration


 Well, you sort of answered your own question.  The equipment is called a
 Thermal Transfer Standard, but instead of thermistors, it uses a
 thermocouple.  Look at the manual for the Fluke 540B
 (http://bama.edebris.com/manuals/fluke/540b/) and you'll see how it's
done.
 Basically, the AC source is input into the transfer standard, and the
 standard's internal reference voltage is adjusted for a null on the
 galvanometer.  Leaving the reference voltage setting alone, a DC voltage
is
 input into the unit, and the DC source is adjusted for a null on the
 galvanometer.  At that point, the AC voltage source is equal to that of
the
 DC voltage source.

 Ther are thermocouple-type thermal converters used for RF voltage
 measurements with the transfer standard.  They aren't cheap, and you have
to
 have a converter for each range of voltages that you need to measure.  The
 thermal converters used with this type of transfer standard isn't great
(50
 MHz or so typical), but their accuracy far surpasses that of the
thermistor
 type sensors.

 There are other brands and models of thermal transfer standards, but I
have
 a Fluke model 540 and a few thermal converters.  That's why I referred you
 to the manual for it.

 Cheers,
 Dave M


 pa4...@gmail.com wrote:
  Is there a way to link an AC voltage to a DC source for compare. I
  can check my calibrators (like a Fluke 332, 760 , 731 and a Philips)
  against standardcells. But for AC I can not do that. I have two AC+DC
  TRMS 7,5 digit meters but the last calibration was 2 years ago.
 
  My idea is in theory simple. It is based on the thermal converters
  used in RF powermeters. Two resistors, two high resolution
  temperature meters. AC on the first en DC on the second. If both are
  the same temperature the AC voltage is the same as the DC voltage.
  But I'm sure some people here have done this in the past. I would
  like to use it for 50 to 100 kHz (or less) and something like for 1V,
  10V and 100V (and use several resistors/heaters.)
 
  Or mabey there is an other way to convert AC (for RF it can be done
  with lightbubs but I never tryed that)  I do not mind if it is slow
  etc, I like this sort of experiments. You can learn a lot from it.
 
  Fred, pa4tim


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

[Bill Gold]

Not that I know of.  Just wait and when you don't see a SMPL on the
display it is done.  But then with 1000 PLC that is around 16.66 seconds per
reading times 100 readings is somewhere around 28 minutes and there is
probably some overhead time so around 30 minutes.  Not from the front panel
at any rate.

Bill

- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Monday, August 25, 2014 9:23 PM
Subject: Re: [volt-nuts] 732A and Prologix received


 Is there any way to tell when the function key routine is complete?  In
the
 case of taking multiple readings using the DEFKEY and MATH function, I
 don't see any indication when the routine is complete.  In one particular
 case, I am taking a 100 readings with NLPC set for 1000 so its a long
while
 before it's complete, but i have to guess when it's done.

 Thanks,

 Randy


 On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans randyevans2...@gmail.com
 wrote:

  Bill,
 
  I am trying to figure out the MATH function without much success.  I
input
  the sequence you said (I looked up the instructions to understand what
you
  did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG;
and
  it shows up on the display when I input BLUE F1.  I hit ENTER and it
takes
  the 40 measurements and the MATH symbol shows on the display during the
  measurements.  After the SMPL symbol no longer blinks I hit MATH 2 and I
  get a MATH ERR symbol on the display.  I tried it a couple of times and
the
  same result so I am doing something wrong.  Is there a better source for
  explaining how to do front panel masurements than the User Guide, which
  seems oriented at programming automatic rather than manual measurements.
 
  Randy
 
 
 
  On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote:
 
  Randy:
 
  The MATH function is accessible from the keypad.  I don't have an
IEEE
  interface right now that works.  You can also program the numeric
keypad
  keys to have preprogrammed functions.  DEFKEY
 
  I have made my own low thermal measurement leads from Pomona
#4892
  banana plugs and Belden #9272 wire.  Why 9272, because it was handy at
the
  time.  It is tin plated copper, shielded twisted pair 20 ga.  I have
plans
  to do custom cables with 16 ga. bare copper wire that I will twist and
  then
  put a braided shield over it.  I simply cannot find what I want so I
will
  build my own cable.  I have done something like this before and it
worked
  fine.  When I get a round toit.
 
  I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have
  used
  in the past to verify my homemade low thermal leads as described
above.
  Frankly I cannot see any difference between using the 1756 cables and
my
  homemade cables once I give them a few minutes for the thermals to go
  away.
  As far as I can tell and measure the differences, if any, are below 0.1
  ppm
  at 10 volts.
 
  Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are
all
  adjustable you may be seeing a misadjusted 1 volt from the 732A.  As
far
  as
  the instability of the readings it is hard to determine which is
causing
  the
  problem.  I have programed (DEFKEY) a numeric keypad key #1 with the
  following code.  MATH 14;NRDGS 40;TRIG 4;TRIG ;   So what this does
is
  set
  the MATH to Statistics (store high reading/low reading/ and mean of
the
  readings) in the registers, the number of readings to 40, the trigger
to
  hold (which keeps the meter from triggering until I press ENTER and
  then
  trigger the sequence of 40 readings when I push the ENTER button.
You
  can
  do all of this manually from the keypads but since I use this sequence
a
  lot
  I have preprogrammed it.  This is after I set digits to 8 and PLC to
  100.
  Once those 40 readings are finished then you can access the various
MATH
  statistic registers, using the menu, by entering MATH and then a 2
for
  low, a 4 for mean, and 13 for high.  Of course you could do all of this
  through the IEEE also.  The 3458A has a very rich set of measurement
  commands.  I am still learning all of them.  It depends upon what I am
  trying to accomplish.
 
  Since the 1.018 and 1.0 volt outputs are passive and derived from
  resistive dividers from the 10 volt, I don't see how they could
contribute
  to the varying readings you are measuring.  I think I would put a short
on
  the input of the 3458A and manually set the range to 1 volt and then
  observe
  the variations that way without the 732A involved.  When I do this I
see a
  variation from low reading to high reading of 0.125 uVolts and then
  another
  40 I get 0.155 uVolts.  This is without the GUARD connected to the low
  side
  of the measurment terminals, GUARD connected doesn't seem to affect the
  readings.  So that is the base noise of the 3458A without the 732A,
  somewhere below .2uVolts.  When hooked up to the 732A 1.0 volt output I
  got

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

[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 tmical...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
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 wpgold3...@att.net wrote:

  Randy:
 
  I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit
  perfect.  Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and
  others
  that are in this size and package.  Order from one of the usual
electronics
  distributors like Allied, Mouser, Digikey.  This is a very common
battery
  as
  it is used in a lot of EXIT signs so they are lighted when the power
goes
  out.  I don't see how the 12V 7AH will fit as they are too large.  I
guess
  you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4
AH
  but the terminals are in the wrong place so you will have to nibble
out
  the aluminum plate that holds them in the 732A battery pack.  You have
to
  be
  careful if you use the 12v 5AH as you will have 4 extra battery
connection
  leads to deal with and connect correctly.  I would stick with the 6V
4AH.
  New batteries will last around 12 to 14 hours before the CAL light
goes
  out when AC power is not applied.  So shipping to Cal Lab can be a
problem
  if it is a distance away, or you have to use a shipper like UPS or FEDEX
  and
  you ship the night before and then use their Morning delivery and the
Cal
  Lab is expecting your 732A.  Same on the way back to you.  Of course you
  could always strap another battery on the 732A and hook it up to the
ext
  power plug to last longer.  I have seen it done.  The issue is to get
the
  Cal Lab to charge the extra battery before they ship the 732A back to
you.
 
  When you remove and work on the battery pack always have the AC
power
  plugged in.  The CAL led will stay on because the 18.6 v regulated
supply
  is working.
 
  The CAL light is to indicate that power has not been lost to the
  Reference Amp or other associated circuits.  When the raw supply
(battery)
  voltage drops below about 21 volts the CAL light will go out.  Below
that
  voltage the heater circuits will not work correctly and the 18.6 volt
  regulated supply will not regulate.  The requirement is that the
Reference
  Amp be kept alive at all times to maintain the output voltage that was
  measured at the time of the most recent Calibration or Certification.
When
  the semiconductor junctions are unbiased and cool off when power is
lost,
  and then power is restored the result will be a different 10 volts than
  before the power failure.  My experience is that after all of the years
  that
  these units have been powered up, this won't happen and when power is
lost
  and then restored, even months later, the 732A will come back to almost
  exactly the same 10 volts as when they lost power, usually with in 0.2
PPM
  after 24 hours of warm up.
 
  What type of hookup leads are you using when measuring the 1 volt
  output?  What is the PLC set to?  I always

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

[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 randyevans2...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Sunday, August 24, 2014 7:22 AM
Subject: Re: [volt-nuts] 732A and Prologix received


 Bill,

 I have convinced myself that the problem I an seeing is due to thermals.
  If I move the cables (with gold-plated banana plugs) using a small towel
 rather than letting my hand touch the plugs, it is much more stable.  If I
 then hold the banana plug with my hand after the reading has stabilized,
 the reading drifts rapidly upward.  I am trying to check the stability of
 the reading but I haven't figured out the MATH function yet.  I assume
this
 is a programmed function using GPIB only?

 The stability I am seeing by manually recording readings (using NLPC of
100
 and 1000) is much greater than what you are measuring on your system.  Not
 sure how to ascertain if it's the 3458A or the 732.  The value of the
 readings are very different between the two - the 3458 reads about 50 uV
 high on the 10 V output and about 12 uV low on the 1V output.  Rather
large
 differences (this is after an ACAL).  I need to find some better cables to
 make sure the errors are not due to thermals again.

 Randy


 On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote:

  Randy:
 
  I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit
  perfect.  Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and
  others
  that are in this size and package.  Order from one of the usual
electronics
  distributors like Allied, Mouser, Digikey.  This is a very common
battery
  as
  it is used

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

[Bill Gold]

Randy:

I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit
perfect.  Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others
that are in this size and package.  Order from one of the usual electronics
distributors like Allied, Mouser, Digikey.  This is a very common battery as
it is used in a lot of EXIT signs so they are lighted when the power goes
out.  I don't see how the 12V 7AH will fit as they are too large.  I guess
you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH
but the terminals are in the wrong place so you will have to nibble out
the aluminum plate that holds them in the 732A battery pack.  You have to be
careful if you use the 12v 5AH as you will have 4 extra battery connection
leads to deal with and connect correctly.  I would stick with the 6V 4AH.
New batteries will last around 12 to 14 hours before the CAL light goes
out when AC power is not applied.  So shipping to Cal Lab can be a problem
if it is a distance away, or you have to use a shipper like UPS or FEDEX and
you ship the night before and then use their Morning delivery and the Cal
Lab is expecting your 732A.  Same on the way back to you.  Of course you
could always strap another battery on the 732A and hook it up to the ext
power plug to last longer.  I have seen it done.  The issue is to get the
Cal Lab to charge the extra battery before they ship the 732A back to you.

When you remove and work on the battery pack always have the AC power
plugged in.  The CAL led will stay on because the 18.6 v regulated supply
is working.

The CAL light is to indicate that power has not been lost to the
Reference Amp or other associated circuits.  When the raw supply (battery)
voltage drops below about 21 volts the CAL light will go out.  Below that
voltage the heater circuits will not work correctly and the 18.6 volt
regulated supply will not regulate.  The requirement is that the Reference
Amp be kept alive at all times to maintain the output voltage that was
measured at the time of the most recent Calibration or Certification.  When
the semiconductor junctions are unbiased and cool off when power is lost,
and then power is restored the result will be a different 10 volts than
before the power failure.  My experience is that after all of the years that
these units have been powered up, this won't happen and when power is lost
and then restored, even months later, the 732A will come back to almost
exactly the same 10 volts as when they lost power, usually with in 0.2 PPM
after 24 hours of warm up.

What type of hookup leads are you using when measuring the 1 volt
output?  What is the PLC set to?  I always use 100 PLC to measure this.  If
you don't have low thermal connection leads you can experience uV changes
for a minute or more after plugging in the leads due to the thermals
generated because of the difference in temperature between the banana jacks
on the 732A and the banana plugs of the leads.  I have found that even just
plugging in the lead will generate a thermal difference because of
difference of temps and some heating due to the physical act of just
inserting the plug because of friction between the jack and plug (my theory
at any rate).  You have to allow at least a minute or more before being able
to make a measurement after plugging in the leads.  I just measured the
variation of the 1 volt output of my 732A and using my 3458A and I got a
total difference of  0.159 uV over 40 measurements using 100 PLC on the 1
volt range of the 3458A.  Using the MATH function and all of the data you
can collect.  That was after waiting for several minutes after plugging in
the leads.

I hope all of this helps.

Bill



- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Friday, August 22, 2014 9:03 PM
Subject: Re: [volt-nuts] 732A and Prologix received


 Todd,

 Thanks for the info.  I have several Panasonic 12V 7 AH batteries that I
 keep topped off and they have very low current draw (~2 to 3 mA at 13.5
 VDC) when charged and at their float voltage, so I am pretty sure they are
 in good condition.  I will look at getting those in the units after I
 ascertain the condition of the 732.

 So now I have a what appears to be a functioning 3458A and a 732A but they
 slightly disagree.  I am like the man with two watches that disagree on
the
 time  - which is correct?  For the moment, i am only concerned with
 stability.  The need for absolute accuracy will come later.

 Randy


 On Fri, Aug 22, 2014 at 8:06 PM, Todd Micallef tmical...@gmail.com
wrote:

  Randy,
 
  You have two possible choices. It can be configured with 4 x 6v 4Ah
  batteries or 2 x 12v 7Ah batteries. Hopefully the previous owner has
  modified the battery pack already. A couple of mine needed a nibbler
tool
  to remove enough of the aluminum cover that fits over the tops of the
  batteries. The original cover will short 

Re: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memorychips?

[Bill Gold]

When I removed the original NVRAM devices and then put in sockets, I plugged
the original devices back in just to see if everything worked.  Apparently
some cal data was lost just desoldering the devices as I got error messages.
It really didn't concern me as I intended to completely recal the meter with
my local standards anyhow.  It was hours before I plugged the original
devices back in so they were completely at room temp.  My guess was that
since the date codes were 1992 and I did this in 2010 the batteries were
almost dead after 18 years and just the shock of desoldering caused the
end.

Bill
- Original Message - 
From: Mark Sims hol...@hotmail.com
To: volt-nuts@febo.com
Sent: Wednesday, August 20, 2014 7:20 PM
Subject: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K
memorychips?


 The problem with removing the chip and copying it is the very real chance
of glitching the contents in the process.  Much better to make a backup copy
first.

 The 32Kx8 NVRAMS are used for system memory and things like storage of
user programs and data.

 Note that the two 32Kx8 devices are form a 16-bit word.  The 2kx8 cal ram
is only on the high byte of the data bus.  MREAD returns memory contents as
a signed integer value (-32768..32767) in ASCII.
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Re: [volt-nuts] HP 3458A Mem test 1 hight. How do youread 32K memorychips?

[Bill Gold]

Correct, I didn't read the NVRAMS.  I didn't have a prom reader/writer that
would handle these devices anyhow and no GPIB interface that worked anymore.
Actually I have two 3458A.  Once I was completely done with the first one
including the cal I didn't even try to put the original NVRAMS removed from
the second meter, just put in the new ones and proceeded to the cal
procedure.

Bill

- Original Message - 
From: J. L. Trantham jlt...@att.net
To: 'Discussion of precise voltage measurement' volt-nuts@febo.com
Sent: Thursday, August 21, 2014 7:53 AM
Subject: Re: [volt-nuts] HP 3458A Mem test 1 hight. How do youread 32K
memorychips?


 Bill,

 Thanks for the insight.

 I always thought that I lost my CALRAM data by trying to read the chip in
my
 programmer while the chip was still warm.  What you are saying is that you
 did not try to read your chip, just unsoldered, installed a socket,
plugged
 it back in and the data was corrupted.

 Very interesting.

 I have done this to three 3458A's and only lost the data on one of the
 units.

 This further supports the need to be able to read the contents before
 unsoldering and have that data be able to be used to program a new chip.

 Thanks for the insight and I would love to try some programs to do that.
I
 only have Windows systems but I have several USB to GPIB adapter choices,
 PCI to HPIB adapter choices, and RS232 to GPIB adapter choices.

 Joe

 -Original Message-
 From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On
 Behalf Of Bill Gold
 Sent: Thursday, August 21, 2014 9:33 AM
 To: Discussion of precise voltage measurement
 Subject: Re: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K
 memorychips?

 When I removed the original NVRAM devices and then put in sockets, I
plugged
 the original devices back in just to see if everything worked.  Apparently
 some cal data was lost just desoldering the devices as I got error
messages.
 It really didn't concern me as I intended to completely recal the meter
with
 my local standards anyhow.  It was hours before I plugged the original
 devices back in so they were completely at room temp.  My guess was that
 since the date codes were 1992 and I did this in 2010 the batteries were
 almost dead after 18 years and just the shock of desoldering caused the
 end.

 Bill
 - Original Message -
 From: Mark Sims hol...@hotmail.com
 To: volt-nuts@febo.com
 Sent: Wednesday, August 20, 2014 7:20 PM
 Subject: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K
 memorychips?


  The problem with removing the chip and copying it is the very real
chance
 of glitching the contents in the process.  Much better to make a backup
copy
 first.
 
  The 32Kx8 NVRAMS are used for system memory and things like storage of
 user programs and data.
 
  Note that the two 32Kx8 devices are form a 16-bit word.  The 2kx8 cal
ram
 is only on the high byte of the data bus.  MREAD returns memory contents
as
 a signed integer value (-32768..32767) in ASCII.
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Re: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memorychips?

[Bill Gold]

John:

I have replaced the 3 NVRAM devices in two different 3458A meters.  I
didn't do anything to the devices other than to install sockets to make
future replacements easier when that issue comes up again.  I did not
program them or anything, just put the blank NVRAMS in and turned on the
meters.  I did get a lot of error messages at turn on because there were no
calibration constants in the devices.  But after clearing those messages
the meter worked normally, but was way off on all readings which was
expected.  I was worried that the other limit constants that were in the
old NVRAM would be reprogrammed into the new NVRAMS but it was all there
just all of the calibration constants were 0 for the most part.

Since I have a complete set of necessary calibration equipment that is
required to completely recalibrate the 3458A I went through all of the
calibration commands with the proper standards hooked up to the meter,  CAL
0, CAL 10.000, CAL 10.000E3 and SCAL and whatever else was required.
When I got done both meters would power on with no problems or complaints
about calibration needed or whatever.

My point here is that putting new blank NVRAMS into the meter does not
cause a Mem test 1 high error.  Of course you must calibrate the entire
meter or send it to HP/Agilent/Keysight or a local lab if you don't have the
necessary equipment to do the cal.

So my guess is that you have a problem on your A5 Outguard Controller
board with addressing memory that is NOT being caused by replacing the
NVRAMS.  Or you have a problem with one of the RAMs on that board or
something.  Unfortunately HP/Agilent/Keysight did not ever publish a full
set of error messages and what they may mean and what to do about them.

Good luck.

Bill

- Original Message - 
From: John Phillips john.philli...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Wednesday, August 20, 2014 1:53 PM
Subject: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K
memorychips?


 Hi,
 I have removed my 32k memory chips form my 3458A. Doe anyone have an easy
 way to connect them to a windows computer. USB would be my preferred
 connection to a 28 and 24  pin socket. I would like to be able to read and
 write to the chips to validate the data.
 I have replace the chips and still get Mem test 1 High on start up.
 ​I really do not want to spend close to $3000 for KeySight to fix this.

 -- 

 *John Phillips*
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Re: [volt-nuts] RE new 3458A

[Bill Gold]

Randy:

Look at page #23 of the 3458A Calibration Manual.  Make yourself a 4
Terminal Short as shown and put it in as shown.

Before I did an ACAL I had around -000.00025 mVDC.  After ACAL I now
read +000.2 mVDC.  I did the CAL 0 myself so I would expect that the
meter should return to a low value, and it does.  I do get a variation of
+/- 30 nVDC using 100 PLC and just observing the variations.  As I remember
I have never seen a spec on the ZERO stability over temperature.

If I turn on the MATH function and then do 40 measurements with 100 PLC
the statistics show:

Low reading-70 nVDC
Mean reading   -28 nVDC
High reading+3.5 nVDC
Total Variation73 nVDC

So that correlates with my visual observation of 60 nVDC.  After an hour
the room had gone up around 1 degree C.  Then I observed -000.00023 mVDC.
After another ACAL the reading was again +000.2 mVDC.  This particular
meter has a negative tempco as the room temp goes up.

Obviously do an ACAL before any precision measurements requiring low
nanovolts.

Go to the Keysight website and go to Technical Support and choose
Parts.  Then enter in the Part Number  03458-66517 which is the
replacement 03458-66507 assembly and you will see the replacement part
number on the right hand side.  Click on that and you will get the
information about the exchange program and so on.  Looks like you can just
order this part online and pay for it with a credit card, but you have to
create or use an existing login account.

I needed a new display a few years ago.  At that time you could order
just the display for around $80.  Being extremely good at removing and then
inserting and soldering I ordered the part.  The problem was that the
spacing from top to bottom of the pins had changed.  It went from around 1.3
inches to around 1.5 inches.  So I had to bend the pins to fit my display
board and then get something like 72 pins into the holes on the PC Board.
It took hours.  This change is probably why HP/Agilent/Keysight doesn't let
you just get the display anymore but wants you to get the whole PC Board
assembly.  It did work just fine once installed.

Hope this helps your decision to keep or not.

Bill



- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Saturday, August 16, 2014 10:36 PM
Subject: Re: [volt-nuts] RE new 3458A


 Interesting note.  After the room cooled down from about 79F to 73F, and
 another ACAL, the meter now reads +000.00035 mVDC, a more reasonable
value,
 although it does bounce around a couple of tenths of a uV.

 Maybe that is OK?  If so, then the only issue would seem to be the
display
 has some faint pixels, which a new display should fix.

 Randy


 On Sat, Aug 16, 2014 at 9:59 PM, Randy Evans randyevans2...@gmail.com
 wrote:

 
  The unit seems to be working so far except for one issue.  After doing
an
  ACAL, and making sure the Auto Zero is ON,  I short the input leads with
a
  copper wire shunt across the inputs and the reading is approximately
   -000.0023 mVDC.  That seems rather high.  I would expect the unit to
short
  the input leads internally and force a zero reading during the ACAL.
  Anyone have any comments on this reading?
 
  Thanks,
 
  Randy
 
 
  On Sat, Aug 16, 2014 at 3:37 PM, Richard Moore richiem5...@gmail.com
  wrote:
 
  Hi Randy -- sounds like your unit is in cal, based on your measurements
  of DCV and precision 10k resistor.
 
  Using autocal all is recommended before doing precision measurements,
and
  I do that if it's been more than a day or two since last use. The
autocal
  uses the internal Vref and an internal 10K resistor to do cal on
everything
  else, so that tells you what the basic cal procedure is. I just got my
3458
  back from Loveland, and that's what they did for me -- warmed it up,
then
  ran autocal, then measured everything against a Fluke 5700, aided by an
HP
  3325, and another 3458.
 
  It has been 5 years since I replaced the display board (no exchange
  deal was available then AFAIK, so I don't know what's changed) and also
the
  NVRAM board, which was dead, with one with the Snap-cap RAM chips. I
did
  those replacements, then sent it home for cal, which was complete,
since
  all the RAM was new. Now after 5 years, the unit passed all incoming
  performance tests and was sent back to me without a cal process of any
  kind. This tells me that an old, well-aged Vref module is a good thing.
The
  10VDC test had changed by a bit under 5ppm, or roughly 1ppm/year.
 
  They have a cal deal -- use code 1.090 -- press them for it -- and that
  saved me 30% off the normal price. I think this deal lasts until
  mid-September, so my recent cal ended up at just under $400 including
  shipping. I'm not sure the deal is available on new or first-time cals;
my
  unit was in their data bank.
 
  But this is a long way of saying I don't think you need to send 

Re: [volt-nuts] Fluke 732A themistor reading

[Bill Gold]

Randy:

I have 6 ea Fluke 732A instruments.  The results of being an over the
edge and deeply obsessed Volt Nut, they just kept adding (reproducing?)
over the years.  My readings for the themistors range from 3.407K OHMS to
4.514K OHMS and all work just fine.  3.6K OHMS would seem just fine to me.
It really depends upon the final inside temp of the oven assembly.  The one
with 3.407K OHMS measures around 47.5 degrees C while the others are around
45 C.  It is the stability of this reading over time that is very important.
Fluke says that it could change as much as 10 ohms per month but mine are
rock solid for years and years.

Bill

- Original Message - 
From: Randy Evans randyevans2...@gmail.com
To: volt-nuts@febo.com
Sent: Sunday, August 17, 2014 11:08 AM
Subject: [volt-nuts] Fluke 732A themistor reading


 Can anyone tell me what value to expect for a Fluke 732A thermistor
 reading?  I am looking to get a used 732A and one of the things I was told
 to look for is to measure the thermistor reading after the unit has heated
 up for at least an hour.  I saw in one of the posts that a typical
 reading was 4950 ohms.  One vendor I asked said he measured about 3600
ohms
 after a two hour warmup. I was concerned that this is too low.  What do
you
 guys think?

 Thanks,

 Randy
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Re: [volt-nuts] A Fluke 732A: Return it or keep it?

[Bill Gold]

Roy:

I use a ( General Cement ) GC 8276 adjustment tool to make the pot
adjustments in the 732A.  I use the end that has the recessed metal blade.
The pots are about 3.5 inches back from the front panel.  It sometimes is
very difficult to engage the tool slot in the pot.  It helps to look through
the front panel hole with a small flashlight and observe the position of the
slot in the pot ( i.e. 9, 10, 11 o'clock for example ).  Then when you
insert the adjustment tool you can get close to the point when you can
engage the adjustment pot.  Sometimes it will seem impossible to engage the
tool into the slot, but with patience it can be done.  Once you do engage
the pot do whatever adjustment you want, don't pull the tool out, just leave
the tool engaged with the pot so that if you want to make another small
change you won't have to go through the same problem of trying again and
again to engage.
I have found that turning the pots may cause a drift which will show up
days later due to the pot being dirty or whatever.  So what I usually do
is to turn the pot back and forth over several revolutions so that I can
clean the contact wiper.  I usually make an initial adjustment and then
turn the pot about 1/32 of a turn in the opposite direction just to relieve
any stress that might be there and cause a small change in the output
voltage.  I usually have very good results with these methods.
But I will agree with Joe that sometimes it is better just to leave
things alone and just use the known offset from 10 volts when checking or
doing cals.
Bill


- Original Message - 
From: Todd Micallef tmical...@gmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Thursday, June 12, 2014 7:20 AM
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?


 Roy,

 The 732A uses the 3059Y-1-101 type cermet pot for the 10V adjustment. You
 can use a simple plastic tweaking tool for adjustment. I believe you will
 need a fairly long tool. You can shine a light into one of the other holes
 to see the orientation of the pot. However, many people may prefer to
leave
 the pot as is and just record the readings. It is going to drift anyway
and
 won't stay adjusted for long. The drift may worsen once the pot position
 has changed too. I have adjusted mine, but only after the broken pots were
 replaced.

 Todd


 On Thu, Jun 12, 2014 at 9:57 AM, R.Phillips phill...@btinternet.com
wrote:

  Hi Joe
  Sorry if I am retracing steps, but I have recently had my 3458A
  restored/recal'd  by Agilent - its good to have it back. I also have a
  Fluke 732A which I can now check. Currently it is 10.24 volts, I now
  feel confident to trim it to the 3458A. I have tried to see the trimmers
in
  each of the three holes - they appear to be some way within, and I am
  wondering if you could confirm the type of pot. that is used and just
how
  long a trimming device is required. Is this a special tool only
available
  from Fluke ?
  Regards
  Roy Phillips.
 
 
  -Original Message- From: J. L. Trantham
  Sent: Saturday, March 08, 2014 10:09 PM
 
  To: 'Discussion of precise voltage measurement'
  Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?
 
  Charles,
 
  What size batteries did you use for your external pack and where are you
  located?  In other words, how long can your external battery pack
'survive'
  keeping the 732A 'hot'?  Is the external pack recharged at Fluke or does
it
  have to make a round trip on the initial charge?  Once I am convinced my
  unit is stable (which will probably be another six months or so, after I
  get
  my 3458A's re-calibrated by Agilent), I hope to be able to send it to
Fluke
  for calibration.
 
  Fluke made a transit case (732A-7002) and a Battery Charger and
Auxiliary
  Battery Case (732A-7003).  However, I have never seen a picture of
either
  of
  these.  Does anyone have any information on these?
 
  How did you make your case?  Did you include a charger?  Combination of
  battery pack and shipping container or separate battery pack and
shipping
  container?
 
  I was thinking of building a case with built-in charger, fuse, and AC
  connector and cord such that when the unit arrived at the CAL facility
all
  that would be needed would be to plug it in and allow the external
battery
  pack to recharge while the unit being calibrated was plugged in,
recharge
  the internal batteries, and calibrated.  Or does the 732A also charge
the
  external battery pack along with the internal batteries?
 
  The connector you need (complete with female contacts) is a Hypertronics
  P/N
  D01PB306FSTAH and is in stock at Kensington Electronics at $8.96 each
(plus
  tax and shipping).  Only problem is their $50 minimum order.
 
  The 'shell' only is P/N D01PB306NT and the female contact is P/N
  YSK006-010ANH (three needed).
 
  http://ecommerce.keiconn.com/hypertronics/D01PB306FSTAH
 
  I ordered two of the connectors from Fluke using a P/N that one of 

Re: [volt-nuts] What made a HP3458A so expensive

[Bill Gold]

Joe:

I would guess that a local JJ would have to be compared with a
standard JJ.  Since NIST says Ours is correct and yours could be a little
more or less than ours, you need to know the difference.  But this all get
into a really gray area in the 0.01 ppm region.  So what are you going to
do?  Move your JJ to NIST?  Not practical!  My suggestion about a JJ in a
9.5 digit was just to get a more stable voltage reference.  Of course at the
present time given the fact that the JJ has to be cooled to below 4.2 K
makes this idea more than a little impractical.  Of course you could setup
to reference the voltmeter to a stand alone JJ in your workshop.  See this
website for a turnkey unit you can get.  www.supracon.comThey have two
models, one which uses liquid He and the other has a Cryocooler.  I am sure
that you can talk the little lady into this as a birthday present?
I am not sure what Fluke does to be traceable to NIST but I would
imagine that Fluke regularly sends carefully characterized 734A units to
NIST in a round robin so that they can accomplish this.  There is an
application note somewhere that talks about this.
Same with the Hz, the ohm and so on, you have to somehow reference it to
NIST, to claim you are traceable to NIST.

Bill

- Original Message - 
From: Joe Hobart n...@npgcable.com
To: Tom Miller tmiller11...@verizon.net; Discussion of precise voltage
measurement volt-nuts@febo.com
Sent: Saturday, January 18, 2014 4:44 PM
Subject: Re: [volt-nuts] What made a HP3458A so expensive


Bill,

Would a Josephson Junction standard need to be calibrated?

Adjusted and maybe compared, yes, but you should not need to calibrate a
primary
standard?  Years ago we had HP Cesium Frequency Standards at work.  There
were
primary standards and good to 4E-12 with no additional calibration.

Joe


On 1/18/2014 3:37 PM, Tom Miller wrote:
 Can you imagine what it would cost to get that calibrated?

 Tom
 - Original Message - From: Bill Gold wpgold3...@att.net
 To: Discussion of precise voltage measurement volt-nuts@febo.com
 Sent: Saturday, January 18, 2014 5:17 PM
 Subject: Re: [volt-nuts] What made a HP3458A so expensive


 In fact if you look at a 1982 HP catalog you will see that the 3456A was
 selling for around $3,700 and given inflation the 3458A is still a pretty
 good bargain when it was introduced in 1989.  In 1989 the 3456A was
selling
 for $4,600 while the 3458A was selling for $5,900.  I wonder if there will

 ever be a 3459A 9.5 digit meter?  With a super miniture Josehpson
Junction
 for a reference?
 Bill

 - Original Message - From: Tom Knox act...@hotmail.com
 To: Discussion of precise voltage measurement volt-nuts@febo.com
 Sent: Saturday, January 18, 2014 1:29 PM
 Subject: Re: [volt-nuts] What made a HP3458A so expensive


 Actually in spite of it's high price I feel the 3458A represents a
bargain.
 When it was introduced in 1989 it was $5900. A price it held for decades.
 Although designed in
 then 80's it's accuracy is still unsurpassed.  The 8846A is much less
 expensive because it has only about a quarter the parts. With few that
 are hand selected and/or aged. And all though both meter have well
 executed designs the result is the 3458A has about a magnitude greater
 accuracy. And anyone in Metrology can attest to the fact that the cost
 of accuracy is exponential. But the thought I wanted to contribute to the
 dialog is the real value of the 3458A is the body
 of knowledge built around the thousands of 358A's some running
 continuously for nearly three decades. The characteristics of the 3458A
 are perhaps the best documented of any electronic instrument ever made.
 That is priceless. When comparing that body of knowledge to individual
 units I have found every 3458A is a little different and seem to each
 have their own personality. In a side note, recently I owned what appeared

 to be the original 3458A. I cannot remember the serial number, but it had
 the numbered stickers identifying the boards that can be seen in the
 original service manual. And it was still  working flawlessly.

 Thomas Knox



 Date: Sat, 18 Jan 2014 17:41:26 +0100
 From: frank.stellm...@freenet.de
 To: volt-nuts@febo.com
 Subject: [volt-nuts] What made a HP3458A so expensive

 Well,

 the 3458A now is in production for about 25 years , and only around 50k
 units have been sold.
 (That's an estimation by Joe Gellers series number collection)

 As the 3458A is a niche product with homeopathic series volume, the
 development, verification/validation, special reliability engineering,
 selection and burn-in measures, QA costs had to be paid per unit in the
 beginning.

 To my opinion, especially the 3458A was designed mainly for military
 requirements (Tamb 55°C). The military was willing to pay a premium (HP
 = High Price) at that time. So HP was able to realize that price.

 All that development budget is long paid, and after end of the Cold War,

 the military does not order

Re: [volt-nuts] What made a HP3458A so expensive

[Bill Gold]

In fact if you look at a 1982 HP catalog you will see that the 3456A was
selling for around $3,700 and given inflation the 3458A is still a pretty
good bargain when it was introduced in 1989.  In 1989 the 3456A was selling
for $4,600 while the 3458A was selling for $5,900.  I wonder if there will
ever be a 3459A 9.5 digit meter?  With a super miniture Josehpson Junction
for a reference?
Bill

- Original Message - 
From: Tom Knox act...@hotmail.com
To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Saturday, January 18, 2014 1:29 PM
Subject: Re: [volt-nuts] What made a HP3458A so expensive


Actually in spite of it's high price I feel the 3458A represents a bargain.
When it was introduced in 1989 it was $5900. A price it held for decades.
Although designed in
then 80's it's accuracy is still unsurpassed.  The 8846A is much less
expensive because it has only about a quarter the parts. With few that
are hand selected and/or aged. And all though both meter have well
executed designs the result is the 3458A has about a magnitude greater
accuracy. And anyone in Metrology can attest to the fact that the cost
of accuracy is exponential. But the thought I wanted to contribute to the
dialog is the real value of the 3458A is the body
of knowledge built around the thousands of 358A's some running
continuously for nearly three decades. The characteristics of the 3458A
are perhaps the best documented of any electronic instrument ever made.
That is priceless. When comparing that body of knowledge to individual
units I have found every 3458A is a little different and seem to each
have their own personality. In a side note, recently I owned what appeared
to be the original 3458A. I cannot remember the serial number, but it had
the numbered stickers identifying the boards that can be seen in the
original service manual. And it was still  working flawlessly.

Thomas Knox



 Date: Sat, 18 Jan 2014 17:41:26 +0100
 From: frank.stellm...@freenet.de
 To: volt-nuts@febo.com
 Subject: [volt-nuts] What made a HP3458A so expensive

 Well,

 the 3458A now is in production for about 25 years , and only around 50k
 units have been sold.
 (That's an estimation by Joe Gellers series number collection)

 As the 3458A is a niche product with homeopathic series volume, the
 development, verification/validation, special reliability engineering,
 selection and burn-in measures, QA costs had to be paid per unit in the
 beginning.

 To my opinion, especially the 3458A was designed mainly for military
 requirements (Tamb 55°C). The military was willing to pay a premium (HP
 = High Price) at that time. So HP was able to realize that price.

 All that development budget is long paid, and after end of the Cold War,
 the military does not order so many devices anymore, what caused the
 problems of the TM business (finally = Keysight, urgh!).

 But as that market is tight, competitors are few, so the price is not
 going down, instead it's increasing over the years, from $5900 to around
 $8500.

 It would be interesting to calcualte the BOM of the 3458A.
 As they use many custom specific components, it should be relatively
 expensive.



 There is no parameter in the HP3458A specifications, that the device has
 to be powered constantly to meet the specs.
 Those very high 8ppm/yr. drift might apply only during continuous
 operation.
 During power down, the LTZ should not drift at all, as the ageing
 mechanism is driven by temperature.
 But there might be (there are indeed) considerable hysteresis effects.

 I have set the temperature of my HP3458A to ~ 60°C, I shut it down after
 usage, and the periodical comparison to 3 other references shows a drift
 of less than 1ppm/year.

 Frank




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Re: [volt-nuts] Connector PN

[Bill Gold]

Randy:

The 3458A CLIP shows this connector as a Molex 22-17-2052.  Looking on
Molex this seems to be a current number.  Mouser and Digikey don't have any
stock.  Alliedelect doesn't show anything.  Good luck.

Bill

- Original Message - 
From: Randy Evans randallgrayev...@yahoo.com
To: volt-nuts@febo.com
Sent: Wednesday, January 15, 2014 6:54 PM
Subject: [volt-nuts] Connector PN


 Does anyone know the manufacturer and part number of the connectors used
on the HP-3458 voltage reference board?

 thanks,

 Randy Evans
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Re: [volt-nuts] Connector PN

[Bill Gold]

update
The HP/AGILENT/KEYSIGHT P/N is 1251-6041 and is in stock at $5.13 ea.

Bill

- Original Message - 
From: Bill Gold wpgold3...@att.net
To: Randy Evans randallgrayev...@yahoo.com; Discussion of precise
voltage measurement volt-nuts@febo.com
Sent: Thursday, January 16, 2014 7:17 AM
Subject: Re: [volt-nuts] Connector PN


 Randy:

 The 3458A CLIP shows this connector as a Molex 22-17-2052.  Looking on
 Molex this seems to be a current number.  Mouser and Digikey don't have
any
 stock.  Alliedelect doesn't show anything.  Good luck.

 Bill

 - Original Message - 
 From: Randy Evans randallgrayev...@yahoo.com
 To: volt-nuts@febo.com
 Sent: Wednesday, January 15, 2014 6:54 PM
 Subject: [volt-nuts] Connector PN


  Does anyone know the manufacturer and part number of the connectors used
 on the HP-3458 voltage reference board?
 
  thanks,
 
  Randy Evans
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Re: [volt-nuts] Fluke 732A/AN Manual

[Bill Gold]

Joe:

Not to steal Todd's thunder but you can find these files on Didier's
ftp site and you can download them from there until he gets a chance to
place them on his regular website.  I have already got them and they are
just like the manual I have.  Great job Todd!  This is the first time I have
seen the latest manual on the 732A/AN.  I was thinking about doing this but
I don't have a great scanner and it takes time to scan a manual like this.
He even has the schematics in B size.

ftp.ko4bb.com

username   u47755086-manuals
password   manuals

Bill

- Original Message - 
From: J. L. Trantham jlt...@att.net
To: 'Discussion of precise voltage measurement' volt-nuts@febo.com
Sent: Monday, January 06, 2014 7:57 PM
Subject: Re: [volt-nuts] Fluke 732A/AN Manual


 Todd,

 Looking forward to the 7332A/AN manual but where did you upload it?

 I looked on Didier's site but did not see anything that looked related to
 the 732A/AN.

 Thanks.

 Joe

 -Original Message-
 From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On
 Behalf Of T. Micallef
 Sent: Monday, January 06, 2014 12:38 PM
 To: volt-nuts@febo.com
 Subject: [volt-nuts] Fluke 732A/AN Manual

 I just received the last couple of missing pages from my manual and
uploaded
 it.

 I deleted two uploads that are now redundant and was able to scan the
 schematics with a large format scanner. Everything should be a lot easier
to
 read now.

 Todd

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Re: [volt-nuts] Fluke 732A Questions

[Bill Gold]

Joe:

A correction on the dropout voltage when the In Cal light goes out, I
found my notes and it is 21 volts instead of 22 volts.  The way I did this
was to remove the battery pack, AC voltage and then just feed in a power
supply where the battery pack would have delivered it's voltage to the
back-plane mother board.  Then I just reduced the voltage until the light
turned off.  So that means that Fluke was following the battery
manufacturers specs of 5.25 volts at the end of the discharge curve.

The banana jacks on the battery pack have two jobs.  One is to provide a
very good chassis ground to the battery pack and the other is probably to
guide the pack accurately into the mother board.  One other thing I have
found out the hard way is that the holes in the top plate of the battery
pack where the battery terminals come through are very close to the battery
terminals and can short out to the chassis.  I have made the holes a LOT
bigger to avoid this problem.  This really depends upon the brand of
batteries you are using but after having to repair the regulator board I
would rather be safe than sorry.

I have 6 Pomona 1756-48 low thermal leads for when I need to be careful
with thermals.  I also have made my own low thermal(I think) using
Pomona 4892 gold plated double banana plugs and Belden 9272 twisted pair
twinax, using a Pomona 1825 for the ground lead.  If I need single banana
plugs to connect to the 732A I use Pomona 4897 gold plated.  I know that
this isn't the best possible low thermal because the wire is tin plated but
I have looked and I can't find a good source of bare copper twisted pair
shielded wire.  When I am making measurements with the home made cables I
just wait a few minutes for the thermals to settle down.  Why Belden 9272?
It was the best choice from what was available at work.  From what I have
seen Pomona was acquired by Fluke and makes special low thermal cables for
Fluke that are not available through the Pomona catalog.

When you find out from Fluke what services they offer and prices please
let all of us know.

Bill

- Original Message - 
From: J. L. Trantham jlt...@att.net
To: 'Discussion of precise voltage measurement' volt-nuts@febo.com
Sent: Tuesday, December 31, 2013 5:13 PM
Subject: Re: [volt-nuts] Fluke 732A Questions


 Bill,

 I have yet to put my 732A though it's paces but I could connect an
external
 power supply, disconnect the AC supply and the battery module and slowly
 decrease the supplied voltage and see what happens when.

 I'll try your measurement algorithm for the battery to see when the 'IN
CAL'
 LED goes out and what the current draws are.  If the measured voltage at
J10
 is 27 V, then the actual battery voltage should be about 27.6 V,
accounting
 for the diode in the circuit (unless the current draw during measurement
is
 so low that no voltage drop occurs across the diode).

 I found the NIST/NBS Tech Note easily.

 I think if I decide to send it out for calibration, I'll use Fluke, if
they
 still calibrate the unit.  I'll call them later this week of next week to
 see what services/accessories they might still have available.

 Yes, I wound up with the 735C.  It was easy to replace the NiCd battery
pack
 and bring it 'on scale' by adjusting the 'jumpers' and the front panel
 adjustment.  I now only have to deal with the periodic 'NO CAL' LED
 indication.  I need to study the 732A manual then take a close look at the
 735C to see how it works on it.

 This also brings up the question of 'low EMF cables' for accurate
 measurement.  I have a Fluke 720A K/V Divider on the shelf that I have yet
 to bring out to check to see if it is operational.  Another one of those
 'projects' for a later time.

 Where would one look for 'low EMF cables' to be used in precise
measurement
 experiments and what errors might one expect to find using Pomona gold
 plated Banana Plug cables (which is as good as I have at this time)?

 Thanks for the info.

 Happy New Year to all.

 Joe


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Re: [volt-nuts] Fluke 732A Questions

[Bill Gold]

 they are for?
 
 I always like to keep equipment as 'original' as possible.  If I can't find
 the correct connector, I'll find something similar that will fit in the same
 hole and use it instead.  We'll see what I hear from Fluke and Hypertronics.
 
 Also, how do you get your 732A calibrated?  Do the batteries last long
 enough to ship overnight to a facility?
 
 Thanks for the info.
 
 Joe
 
 -Original Message-
 From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On
 Behalf Of Bill Gold
 Sent: Monday, December 30, 2013 7:03 PM
 To: Discussion of precise voltage measurement
 Subject: Re: [volt-nuts] Fluke 732A Questions
 
 Joe:
 
 My 732A units vary in thermistor resistance from 3.408K ohms to 4.514K
 ohms and have been extremely stable to with in +/- 5 ohms for years now.  I
 did measure the oven temperature of the one with the 3.408K ohms just to see
 what was causing the thermistor resistance to be a little low and came up
 with about 47 degrees centigrade, as best as my equipment would allow me to
 measure it.  Equipment was a Fluke 80TK thermocouple module, a Fluke 80 PK-1
 thermocouple bead and a HP 3456A DVM.  I put shrink wrap around the bead and
 then threaded the bead into the temperature oven through one of the
 adjustment holes in the front panel and made sure that it was far into the
 oven, probably around the middle.  Then I checked another unit that read
 4.5K ohms and it read around 43 degrees C so all of that made sense.  I
 believe I saw somewhere that the spec was 45 degrees C +/- 2 C.
 
 I did have to change the jumpers on the Calibration PCB Assembly on
 one of my units so that it would match other 732A units that were In Cal
 and had certified values.  But that unit has since drifted down at a rate of
 around 1.2 ppm per year which is with in specs but a little more than I have
 seen from other units.  Recently this unit has suddenly quit drifting down
 and seems a lot more stable now.  That was S/N 459.  I have a S/N
 343 which has been proven rock solid for years now at around +/- .3 ppm
 and just seems to have DC noise stability as it just goes up a little and
 then down a little and never needed any adjustment.  I also have a S/N
 460 which is extremely stable also.  So I guess that age does seem to
 factor into stability as well as how long they have been powered up.  But
 the only way to insure that you have a good volt is to have at least 4
 units and then inter-compare them periodically following NIST (NBS)
 Technical Note #430.  While 430 was written for Saturated Standard Cells,
 the technique seems to work just fine at 10 volts also.  You can also find
 this measurement technique in the 1st Fluke Calibration - Philosophy in
 Practice book published around 1974.
 
 I gave up on the unobtainium connector on the back of the battery pack
 very quickly.  I drilled a 1/4  holes on either side of the unobtainium
 connector, after removing it, and used two single miniature banana jacks to
 allow me to connect to the batteries for the purpose of checking their
 performance as described in the 732A manual page 2-9 in manual P/N 788414
 May 1986.  I should probably turn in my resignation as a volt nut for this
 action but it works.  KISS.
 
 Bill
 
 
 - Original Message -
 From: J. L. Trantham jlt...@att.net
 To: volt-nuts@febo.com
 Sent: Saturday, December 28, 2013 2:51 PM
 Subject: [volt-nuts] Fluke 732A Questions
 
 
  I have reviewed the prior postings on Volt-nuts (a very rewarding review,
  BTW)) regarding the 732A and have two questions:
 
 
 
  1.Has anyone determined the part number, or a source, for the
 mating
  plug to J10, the external power connector for the 732A-7005 battery pack?
 I
  noted some postings recently about this but did not find a definitive
  response regarding the identity of this plug.  The alternative would
 appear
  to be a complete replacement of J10 and its plug, as long is it all fits
 in
  the opening in the panel.  I hate to 'bore holes' in vintage equipment.
 
  2.   The oven thermistor in my 'new to me' unit measures 4229 ohms
 (+/-
  an ohm or two) after the unit has warmed up for a week or so.  I note the
  manual refers to 3K to 4K for the value of this thermistor when the unit
 is
  'stable' as well as other's posting values in the mid 3500's ohms for
 their
  units.  Should I be concerned?  The unit seems to be stable to within
 about
  2 uV over about a week (as measured by my 3458A - see below).  Should I
 open
  the unit and try to measure the oven temperature or just be satisfied that
  the unit seems to be working?
 
 
 
  I had to replace the four 6V 4AH SLA batteries and they charged up
  appropriately as judged by the front panel LED's.  I had to remove the
  'jumper' for the '40' option on the A7 board and connect the jumper to the
  '20' and '10' options (total of '30') in order to get the unit to adjust
 to
  10.000 VDC on my 'Agilent In Cal'd' 3458A.
 
 
 
  The need

Re: [volt-nuts] Fluke 732B

[Bill Gold]

Joe:

The 731A and 731B were run at room temp and therefore were subject to room 
variations.  They both use the same Reference Amplifier as the 732A  B use.  
I have one 731B and it is amazingly stable for the room temp variations I 
experience at home.  When I was working we had a 731B that was also very good.  
I had sent it for calibration over a 10 year period and the drift was equal to, 
or better than the 732 series.  At the end of the 10 years it was absolutely 
stable at less than 1 ppm.  This was all being done at a Fluke Service Center 
that was located in Milpitas California, and their 732As were being routinely 
sent to Fluke in Everett WA.

The difference between the 731  732 is that starting with the 732A all of 
the temperature sensitive components were enclosed in a oven assembly that had 
heaters surrounding the oven enclosure which is running at 45 degrees C.  This 
includes all of the resistors and adjustment pots.  I have torn down a 732A to 
the oven assembly and gone inside the assembly to replace a component.  It is a 
real trick to do this, but by being careful it can be done.

The fact that the 732As have been in operation for a much longer period of 
time probably explains the lower drift rates than the 732Bs.  The 732As have 
been aged much longer.  I know people who prefer the 732A over the 732B 
because of this.  The only problem with the 732A is that the heaters use more 
power than the 732Bs.  Early manuals spec 24 hour battery operation, but later 
manuals have changed that to 12 hours.  All of the 732As I have observed will 
only run for about 12 to 15 hours before the in cal light goes out meaning 
that the batteries have dropped below about 22 volts.  The 732B is speced at 72 
hours battery operation but I have no experience if this is true.

I guess I am a real Volt-Nut in that I have 6 732As at home right now.  I 
inter-compare them once a week.  The last time I was able to verify what the 
official volt is was in 2005.  Right now I need to find a good Cal Lab in the 
South SF Bay Area where I can have one of them certified against their 
traceable standards.  The Fluke service center was closed years ago.

Bill
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Re: [volt-nuts] Fluke 732B

[Bill Gold]

Joe:

Thanks for the upgrade, but they are only 732As not Bs.  I got all of these 
at less than the going price of one 732B that recently sold on the infamous 
action site.

Bill
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Re: [volt-nuts] Fluke 732B

[Bill Gold]

Joe:

That was a very interesting teardown of the 732B on eevblog.  The one thing 
that this answered for me was if Fluke was using their Reference Amplifier in 
all of the 732B production and Fluke did.

If you look at a paper by David Deaver called Predictability of Solid 
State References which he wrote, and you can download from the Fluke website 
http://us.fluke.com/. you will see on page three of the paper that he talks 
about the reference drifts of a number of 732Bs that were checked over a period 
of time.  Deaver talks about Motorola References and Linear Technology 
References and that the Motorola's drift upwards while the Linear Tech's drift 
downwards over time.  Also look at Fig. 10.  I was assuming (wrongly of course 
as I see now) that Fluke had switched from the Reference Amplifier to the 
LTZ1000 in the production of the 732B.  Now I see that it is just what company 
made the Reference Amplifiers for Fluke.  Of course the 4 legged device is a 
Reference Amplifier that they have used for a least 25 years or more as the 
voltage reference in a lot of their instruments.

I have never seen a schematic of the super secret oven assembly but you 
can probably bet that it looks a lot like the 732A but with a lot more black 
magic built into it.  I don't think that Fluke would ever expect someone to 
fix this beyond the unit replacement level as I am sure that this would require 
factory precedures far beyond anything that we could muster in the field.  Part 
of the black magic is adjusting the collector current of the reference 
amplifier to obtain a zero TC around a very limited range of operating 
temperatures.  The digital adjustments also add something inside the oven 
assembly, probably a DAC, and it would be interesting what they are doing 
there, so a schematic would be interesting to see.

Anyway I will quit rambling.  So many things to do, so little time.

Bill
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Re: [volt-nuts] (New to me) 3458A Trivia

[Bill Gold]

Speaking of the 03458-66529 reference board added to the HP 3458A by Fluke 
(before Fluke offered the 8508A), has anyone ever seen a schematic of that 
board or how Fluke could rate that reference at 2 ppm?  One person on this 
forum theorized that by lowering the operating temperature of the LTZ1000A to 
around 70 degrees C, which is what the LTC device specification note 
recommends, this might have what was done to achieve the better drift 
specification.  It was noted that HP was running the LTZ1000A at around 105 
degrees C which might accelerate the aging rate.  I lowered my references to 
around 70 C and they have seemed to be a little more stable when checked 
against the Fluke 732A DC Reference Standard.  But I never started a project to 
follow up on this theory.  Just another project to play with when I get a 
round toit
Bill
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