[volt-nuts] Low noise reference

[Randy Evans]

I have a question for the group.  I was looking at an article for building
an ultra-low noise voltage reference by Walt Jung, published in Electronic
Design June 24, 1993 and a URL to the article is below.  I want to filter
the output of an LTZ1000 based 10V reference I am building and this circuit
has a very low freq corner of 1.6 Hz.  I was concerned about the leakage
through R1-C1.  If C1 had as little as 1ua leakage, it would drop the
voltage through R1 by 1 mV.  The spec on 100 uF electrolytic and tantalum
capacitors show a leakage of 20 ua  at rated voltage so this could be of
great concern.  However, at the low few tenths of a volt that should be
across C1, the capacitor should have a much lower leakage amount, which is
the theme of the article.

To get a better appreciation of the issue, I connected a precision 0 to 10
V source (100uV resolution steps) to a series combination of a 1 Kohm
resistor and a 100 uF electrolytic and, later, another 47uF tantalum and a
47 uF electrolytic capacitor.  In all cases the leakage, as measured with a
Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V and
varying 0.04 to 0.12 uA, around .1uA at 1V and varying , and around 1 pA at
0.1V, but with widely varying leakage current of 0.5 to 1.5 pA, with
occasional peaks of -0.5 to 2 pA.  This would equate to about +/- 2 uV
voltage variation across R1, making a 10 V 0.1ppm stable voltage reference
of questionable value.

I also tried a 0.68 uF polystyrene capacitor and also saw leakage current
variations, although much less than the electrolytic and tantalum
capacitors, as one would expect.

Thinking the problem might be the the picoammeter, I put a 100 megohm 0.1%
precision resistor in place of the capacitor across the precision voltage
source set for 0.1 V and measured the current through the resistor at a
very stable 0.9 pA on the Keithley 414 (sb 1pA but accurate enough for my
measurements - the resistor shielded box likely has some sub pA leakage
also).  Note that I used shielded cables for all measurements, and the
resistor and capacitor were in a shielded box, as well as the 100 Mohm
calibration resistor.  Touching the cables or boxes did not change the
picoammeter reading at all, indicating to me that the shielding was
reasonable.

I suppose the best approach is to build it and characterize it, but it's
not fruitful if someone has already done this. So my question is: has
anyone built this circuit and characterized it, particularly over
temperature for stability at the sub ppm level?

Thanks,

Randall Evans







http://waltjung.org/PDFs/Build_Ultra_Low_Noise_Voltage_Reference.pdf
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Neon bulbs for HP 3420B or 419A chopper

[Randy Evans]

Is there a relaible source for the GT-NE6H1925T neons?  Mouser has them for
special order and I suspect they want a high minimum quantity.  A source in
China lists them but I'm not sure I trust a Chinese source.

On Sat, Jan 6, 2018 at 8:19 AM, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:

> An update the A2B neons didn't work, but:
>
> George Kerber sent me a few GT-NE6H1925T neons.  I pulled two out the
> packet and installed them in the chopper, and wonder of wonders the correct
> waveform appeared at the test point.
>
> This is a great step forward.   The earlier neons I tried had way too low
> a firing voltage so both fired.  These fired at about 95-100V with a
> sustain at about 68V and do alternate.
>
> Dave
>
> -Original Message-
> From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C.
> Partridge
> Sent: 18 November 2017 14:08
> To: 'Discussion of precise voltage measurement'
> Subject: Re: [volt-nuts] Neon bulbs for HP 3420B or 419A chopper
>
> I'm in the process of getting some A2B neons from Mouser.
>
> Dave
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

The routine looks like this on the Output Console:

HP3458A
24.4
0

1



The 0 pops up after several seconds and the 1 after even more seconds
later.  No other output after the 1.

The temperature reading is OK but no voltage readings.


Thanks for the assistance but I likely have a hardware issue.  I did the
service note 13A test and the unit passed it fine.  I will have to do more
troubleshooting on my own but I really appreciate the help.

Randy Evans.

On Sun, Dec 31, 2017 at 6:09 AM, Todd Micallef <tmical...@gmail.com> wrote:

> Randy,
>
> I put together a quick script for testing your connection. I have emailed
> it to you but attached it here for others if needed. It will be easier than
> running the other program.
>
> Todd
>
> On Sun, Dec 31, 2017 at 9:00 AM, Dr. Frank <frank.stellm...@freenet.de>
> wrote:
>
> > Randy,
> >
> > I doubt, that your hp unit is defective, as it might work under certain
> > circumstances, and also the FW version 8.2 vs. 9.2 will not make any
> > difference, as only a few pair of bytes are different. All versions of
> the
> > A5 board are designed to be completely interchangeable over all versions
> of
> > 3458A instruments.
> >
> > I have another theory, which deals with the hardware version difference
> > between the agilent and the hp unit.
> >
> > Your agilent unit might already have the 66547, full SMD board for A5,
> > whereas the hp will for sure have one of the old 66505/515, through- hole
> > boards, Rev A, B, or C. Illya has all of them pictured in his first 3458A
> > repair blog.
> >
> > All the  old versions (A, B, C) have GPIB bus transceivers, TI 75ALS160
> > for the data bus, and NS 75161 for the handshake signals.
> > The new SMD board has TI 75ALS160 / TI 75ALS161, instead.
> >
> > So, the handshake bus uses a different logic family for the new board,
> and
> > therefore, the logic levels / immunity might be slightly different.
> >
> > My hp3458A has got the REV C A5 board, and it's from 2000.
> > Since 2009, I run a similar datalogging program for capturing LTZ1000
> > output versus time, each 4 seconds, on an old PC with WIN98, Turbo
> Pascal,
> > an XT bus GPIB card from CEC, with the NEC chip.
> >
> > This program and hardware ran properly for years, (decades), until more
> > and more errors during the 24h acquisition runs occured, vaguely
> reminding
> > me of your trouble.
> > The output values were always correct, but frequently, 10sec time-outs
> > ocurred, giving zero readings in the datalog. This time-out is obviously
> > related to the handshaking mechanism.
> > Finally, I found out, that the old ATX PSU was failing, especially its
> > input snubber network was gone defect, which probably created big EMC
> > spikes.
> > After replacing the PSU, all these errors vanished completely.
> >
> > My conclusion was, that the GPIB bus is susceptible to such EMC
> > disturbances, although it's solid TTL logic.
> > As obviously the handshake signals were affected only, their higher
> > susceptibility to disturbances may be caused by the difference in the
> logic
> > family of the transceiver IC. The agilent 3458A might be more tolerant to
> > that, having the ALS161 version, instead.
> >
> > So you might also look for EMC problems in your lab, like SMPS, LED
> lamps,
> > or a defective PC power supply.
> >
> > Maybe, these Prologix adaptors (clones?) have critical logic levels,
> > especially on the handshake bus, or an improper ground.
> > You might search for these signal problems directly on the GPIB cable.
> >
> > Frank
> >
> > ___
> > volt-nuts mailing list -- volt-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/m
> > ailman/listinfo/volt-nuts
> > and follow the instructions there.
> >
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

Since the KE5FX NVRAM download software works, that would seem to indicate
the GPIB is working, wouldn't it (download completes and checksums OK)?

Randy

On Sat, Dec 30, 2017 at 9:52 PM, Randy Evans <randyevans2...@gmail.com>
wrote:

> Todd,
>
> The minimal quick test would be greatly appreciated if you have the time.
> I know this is above and beyond what I would expect but it would be really
> useful to see if there is any hope for the GPIB on this unit.  I will do
> the service note 13 procedure in the morning.
>
> Thanks again,
>
> Randy
>
> On Sat, Dec 30, 2017 at 8:58 PM, Todd Micallef <tmical...@gmail.com>
> wrote:
>
>> Randy,
>>
>> Short of swapping out the A5 digital board I have no other ideas. If you
>> don't have a NI or Agilent adapter, I am sure I can find a spare for you
>> to
>> test.
>>
>> There is a Service Note 3458A-13A that deals with GPIB communication
>> failures. There is a test within the document to see if a shorting jumper
>> needs to be installed.
>> I can try reducing the code to something minimal for a quick test if you
>> want. It will take some time in the morning.
>>
>> Todd
>>
>> On Sat, Dec 30, 2017 at 11:18 PM, Randy Evans <randyevans2...@gmail.com>
>> wrote:
>>
>> > Todd,
>> >
>> > Same as before.  Still not working.  All it does is print out "HP3458A"
>> on
>> > the output console and then just sits there.
>> >
>> > Randy
>> >
>> > On Sat, Dec 30, 2017 at 7:43 PM, Todd Micallef <tmical...@gmail.com>
>> > wrote:
>> >
>> > > Randy,
>> > >
>> > > I just remembered that I changed the duration from 30 minutes to 2
>> > minutes
>> > > to speed up the test. I forgot to change it back.
>> > >
>> > > Todd
>> > >
>> > > On Sat, Dec 30, 2017 at 10:27 PM, Todd Micallef <tmical...@gmail.com>
>> > > wrote:
>> > >
>> > > > Randy,
>> > > >
>> > > > I just sent it. I haven't modified Martin's code yet. That can be
>> done
>> > > > once you confirm it works for you.
>> > > >
>> > > > Todd
>> > > >
>> > > > On Sat, Dec 30, 2017 at 10:12 PM, randyevans2688 <
>> > > randyevans2...@gmail.com
>> > > > > wrote:
>> > > >
>> > > >> Todd,
>> > > >> If you don't mind,  just send the code directly to me.
>> > > >> Randy
>> > > >>
>> > > >> Sent from my Verizon, Samsung Galaxy smartphone
>> > > >>  Original message From: Todd Micallef <
>> > > >> tmical...@gmail.com> Date: 12/30/17  6:40 PM  (GMT-08:00) To:
>> > > Discussion
>> > > >> of precise voltage measurement <volt-nuts@febo.com> Subject: Re:
>> > > >> [volt-nuts] GPIB Issue with 3458A
>> > > >> Randy,
>> > > >>
>> > > >> I have not written anything else for the 3458A using EzGPIB.  If
>> you
>> > > have
>> > > >> a
>> > > >> National Instruments or Agilent adapters, I have a handful of
>> Python
>> > > code
>> > > >> I
>> > > >> use to measure some of my standards.
>> > > >>
>> > > >> If you are reading the temperature from the HP meter, I would think
>> > that
>> > > >> the problem lies in how the triggering is configured. The
>> triggering
>> > has
>> > > >> been changed in this script so it may work for you. There was an
>> > > >> additional
>> > > >> command added for disabling the buffer.
>> > > >> The code can be posted here, if possible or I can email it to you
>> for
>> > > >> testing.
>> > > >>
>> > > >> Todd
>> > > >>
>> > > >> On Sat, Dec 30, 2017 at 9:26 PM, randyevans2688 <
>> > > randyevans2...@gmail.com
>> > > >> >
>> > > >> wrote:
>> > > >>
>> > > >> > Todd, thanks for the help.  Where will you post the new code?
>> > > >> > BTW, do you have any very simple code that is likely to work.  I
>> am
>> > > >> > interested in seeing if anything other than KE5FX's memory dump
>> > >

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

The minimal quick test would be greatly appreciated if you have the time.
I know this is above and beyond what I would expect but it would be really
useful to see if there is any hope for the GPIB on this unit.  I will do
the service note 13 procedure in the morning.

Thanks again,

Randy

On Sat, Dec 30, 2017 at 8:58 PM, Todd Micallef <tmical...@gmail.com> wrote:

> Randy,
>
> Short of swapping out the A5 digital board I have no other ideas. If you
> don't have a NI or Agilent adapter, I am sure I can find a spare for you to
> test.
>
> There is a Service Note 3458A-13A that deals with GPIB communication
> failures. There is a test within the document to see if a shorting jumper
> needs to be installed.
> I can try reducing the code to something minimal for a quick test if you
> want. It will take some time in the morning.
>
> Todd
>
> On Sat, Dec 30, 2017 at 11:18 PM, Randy Evans <randyevans2...@gmail.com>
> wrote:
>
> > Todd,
> >
> > Same as before.  Still not working.  All it does is print out "HP3458A"
> on
> > the output console and then just sits there.
> >
> > Randy
> >
> > On Sat, Dec 30, 2017 at 7:43 PM, Todd Micallef <tmical...@gmail.com>
> > wrote:
> >
> > > Randy,
> > >
> > > I just remembered that I changed the duration from 30 minutes to 2
> > minutes
> > > to speed up the test. I forgot to change it back.
> > >
> > > Todd
> > >
> > > On Sat, Dec 30, 2017 at 10:27 PM, Todd Micallef <tmical...@gmail.com>
> > > wrote:
> > >
> > > > Randy,
> > > >
> > > > I just sent it. I haven't modified Martin's code yet. That can be
> done
> > > > once you confirm it works for you.
> > > >
> > > > Todd
> > > >
> > > > On Sat, Dec 30, 2017 at 10:12 PM, randyevans2688 <
> > > randyevans2...@gmail.com
> > > > > wrote:
> > > >
> > > >> Todd,
> > > >> If you don't mind,  just send the code directly to me.
> > > >> Randy
> > > >>
> > > >> Sent from my Verizon, Samsung Galaxy smartphone
> > > >>  Original message From: Todd Micallef <
> > > >> tmical...@gmail.com> Date: 12/30/17  6:40 PM  (GMT-08:00) To:
> > > Discussion
> > > >> of precise voltage measurement <volt-nuts@febo.com> Subject: Re:
> > > >> [volt-nuts] GPIB Issue with 3458A
> > > >> Randy,
> > > >>
> > > >> I have not written anything else for the 3458A using EzGPIB.  If you
> > > have
> > > >> a
> > > >> National Instruments or Agilent adapters, I have a handful of Python
> > > code
> > > >> I
> > > >> use to measure some of my standards.
> > > >>
> > > >> If you are reading the temperature from the HP meter, I would think
> > that
> > > >> the problem lies in how the triggering is configured. The triggering
> > has
> > > >> been changed in this script so it may work for you. There was an
> > > >> additional
> > > >> command added for disabling the buffer.
> > > >> The code can be posted here, if possible or I can email it to you
> for
> > > >> testing.
> > > >>
> > > >> Todd
> > > >>
> > > >> On Sat, Dec 30, 2017 at 9:26 PM, randyevans2688 <
> > > randyevans2...@gmail.com
> > > >> >
> > > >> wrote:
> > > >>
> > > >> > Todd, thanks for the help.  Where will you post the new code?
> > > >> > BTW, do you have any very simple code that is likely to work.  I
> am
> > > >> > interested in seeing if anything other than KE5FX's memory dump
> > > program
> > > >> > will work on my HP3458A.
> > > >> > Thanks again,
> > > >> > Randy
> > > >> >
> > > >> > Sent from my Verizon, Samsung Galaxy smartphone
> > > >> >  Original message From: Todd Micallef <
> > > >> tmical...@gmail.com>
> > > >> > Date: 12/30/17  6:13 PM  (GMT-08:00) To: Discussion of precise
> > voltage
> > > >> > measurement <volt-nuts@febo.com> Subject: Re: [volt-nuts] GPIB
> > Issue
> > > >> with
> > > >> > 3458A
> > > >> > Randy,
> > > >> &g

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

Same as before.  Still not working.  All it does is print out "HP3458A" on
the output console and then just sits there.

Randy

On Sat, Dec 30, 2017 at 7:43 PM, Todd Micallef <tmical...@gmail.com> wrote:

> Randy,
>
> I just remembered that I changed the duration from 30 minutes to 2 minutes
> to speed up the test. I forgot to change it back.
>
> Todd
>
> On Sat, Dec 30, 2017 at 10:27 PM, Todd Micallef <tmical...@gmail.com>
> wrote:
>
> > Randy,
> >
> > I just sent it. I haven't modified Martin's code yet. That can be done
> > once you confirm it works for you.
> >
> > Todd
> >
> > On Sat, Dec 30, 2017 at 10:12 PM, randyevans2688 <
> randyevans2...@gmail.com
> > > wrote:
> >
> >> Todd,
> >> If you don't mind,  just send the code directly to me.
> >> Randy
> >>
> >> Sent from my Verizon, Samsung Galaxy smartphone
> >>  Original message From: Todd Micallef <
> >> tmical...@gmail.com> Date: 12/30/17  6:40 PM  (GMT-08:00) To:
> Discussion
> >> of precise voltage measurement <volt-nuts@febo.com> Subject: Re:
> >> [volt-nuts] GPIB Issue with 3458A
> >> Randy,
> >>
> >> I have not written anything else for the 3458A using EzGPIB.  If you
> have
> >> a
> >> National Instruments or Agilent adapters, I have a handful of Python
> code
> >> I
> >> use to measure some of my standards.
> >>
> >> If you are reading the temperature from the HP meter, I would think that
> >> the problem lies in how the triggering is configured. The triggering has
> >> been changed in this script so it may work for you. There was an
> >> additional
> >> command added for disabling the buffer.
> >> The code can be posted here, if possible or I can email it to you for
> >> testing.
> >>
> >> Todd
> >>
> >> On Sat, Dec 30, 2017 at 9:26 PM, randyevans2688 <
> randyevans2...@gmail.com
> >> >
> >> wrote:
> >>
> >> > Todd, thanks for the help.  Where will you post the new code?
> >> > BTW, do you have any very simple code that is likely to work.  I am
> >> > interested in seeing if anything other than KE5FX's memory dump
> program
> >> > will work on my HP3458A.
> >> > Thanks again,
> >> > Randy
> >> >
> >> > Sent from my Verizon, Samsung Galaxy smartphone
> >> > ---- Original message From: Todd Micallef <
> >> tmical...@gmail.com>
> >> > Date: 12/30/17  6:13 PM  (GMT-08:00) To: Discussion of precise voltage
> >> > measurement <volt-nuts@febo.com> Subject: Re: [volt-nuts] GPIB Issue
> >> with
> >> > 3458A
> >> > Randy,
> >> >
> >> > I found the Prologix adapters and have modified the code in the
> original
> >> > script. I am doing a test run now and will post the script when I am
> >> > certain I didn't make it worse.
> >> >
> >> > Todd
> >> >
> >> > On Sat, Dec 30, 2017 at 7:15 PM, Randy Evans <
> randyevans2...@gmail.com>
> >> > wrote:
> >> >
> >> > > Todd,
> >> > >
> >> > > I have swapped cables, moved the Prologix adapter to both meters
> >> (Agilent
> >> > > works, HP doesn't), tried Martins code as well as Xdevs's.  I have
> not
> >> > > tried another PC yet, maybe the next step.
> >> > >
> >> > > Here is the code that Martin modified for two meters, as well as the
> >> > > modified Xdev's code per your directions (V1.02).
> >> > >
> >> > > Thanks,
> >> > >
> >> > > Randy
> >> > >
> >> > > On Sat, Dec 30, 2017 at 3:55 PM, Todd Micallef <tmical...@gmail.com
> >
> >> > > wrote:
> >> > >
> >> > > > Randy,
> >> > > >
> >> > > > I will continue to look for my adapter. I haven't used it for
> quite
> >> a
> >> > > > while.
> >> > > >
> >> > > > I have seen similar issues and swapped cables, moved the adapter
> to
> >> the
> >> > > > other meter, etc... One of my cables was bad from one side of the
> >> > > connector
> >> > > > to the other (on the same end of the cable) and caused me lots of
> >> > wasted
> >

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

I have swapped cables, moved the Prologix adapter to both meters (Agilent
works, HP doesn't), tried Martins code as well as Xdevs's.  I have not
tried another PC yet, maybe the next step.

Here is the code that Martin modified for two meters, as well as the
modified Xdev's code per your directions (V1.02).

Thanks,

Randy

On Sat, Dec 30, 2017 at 3:55 PM, Todd Micallef <tmical...@gmail.com> wrote:

> Randy,
>
> I will continue to look for my adapter. I haven't used it for quite a
> while.
>
> I have seen similar issues and swapped cables, moved the adapter to the
> other meter, etc... One of my cables was bad from one side of the connector
> to the other (on the same end of the cable) and caused me lots of wasted
> time. Weird reading errors were happening.
>
> Would you email me Martin's code so I can test it here and I will see if
> anything can be done to replicate your issue.
>
> Todd
>
>
> On Sat, Dec 30, 2017 at 6:42 PM, Randy Evans <randyevans2...@gmail.com>
> wrote:
>
> > Todd,
> >
> > I tried adding the line but it made no difference.
> >
> > Randy
> >
> > On Sat, Dec 30, 2017 at 12:19 PM, Randy Evans <randyevans2...@gmail.com>
> > wrote:
> >
> > > Todd,
> > >
> > > Does it matter where I put the line in the Init_Device procedure?
> > >
> > >
> > > procedure Init_Device;
> > > begin;
> > >EZGPIB_BusWriteData(gpib_address,GET_ID);// Get ID of
> > meter
> > >if EZGPIB_BusWaitForData(gpib_address,meter_id,Timeout) then
> > > EZGPIB_ScreenWriteLn(meter_id);
> > >
> > >EZGPIB_BusWriteData(gpib_address,TRIGGER_SOURCE);// Hold
> trigger
> > > until meter can be setup
> > >EZGPIB_BusWriteData(gpib_address,'INBUF ON');
> > >EZGPIB_BusWriteData(gpib_address,AUTO_ZERO);
> > >EZGPIB_BusWriteData(gpib_address,OUTPUT_FORMAT);
> > > end;
> > >
> > >
> > > Randy
> > >
> > > On Sat, Dec 30, 2017 at 11:20 AM, Todd Micallef <tmical...@gmail.com>
> > > wrote:
> > >
> > >> Randy,
> > >>
> > >> I am the person that wrote that EzGPIB script. It was my first before
> I
> > >> moved on to Python and I have only written a couple for the different
> > >> meters I have on hand. Version 1.01 is the most current version I have
> > for
> > >> the 3458A.
> > >> I see that I should have added at least one more command to the meter
> > >> initialization.  The additional init command is used in the scripts on
> > >> xDevs.
> > >>
> > >> Add the following line in the Init_Device procedure
> > >>EZGPIB_BusWriteData(gpib_address,'END ALWAYS');
> > >>
> > >> This tells the meter to send an EOI on every read.
> > >>
> > >> I am looking for one of my Prologix adapters or I would test this.
> When
> > I
> > >> find it, I will also test it. I want to make sure there are no further
> > >> issues.
> > >> Also, do both meters run the same firmware versions? I wonder if the
> HP
> > >> meter is using a much older version.
> > >>
> > >> Todd
> > >>
> > >> On Sat, Dec 30, 2017 at 10:42 AM, Randy Evans <
> randyevans2...@gmail.com
> > >
> > >> wrote:
> > >>
> > >> > Todd,
> > >> >
> > >> > I have version 1.01. Yes, please e-mail me your modified version.
> > >> Maybe it
> > >> > will help.
> > >> >
> > >> > Thanks,
> > >> >
> > >> > Randy
> > >> >
> > >> > On Sat, Dec 30, 2017 at 4:24 AM, Todd Micallef <tmical...@gmail.com
> >
> > >> > wrote:
> > >> >
> > >> > > Randy,
> > >> > >
> > >> > > Is there a version number at the top of the file? I had two
> versions
> > >> > (1.00
> > >> > > and 1.01). I can't remember all that changed between the two since
> > it
> > >> has
> > >> > > been a while but I did find an additional timeout code that
> limited
> > >> the
> > >> > > wait time for reading data to 1 minute. I am guessing I had a
> > problem
> > >> > with
> > >> > > mine and added it.
> > >> > >
> > >> > > I can email it to you if you want to try it. If it works for you,

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

I tried adding the line but it made no difference.

Randy

On Sat, Dec 30, 2017 at 12:19 PM, Randy Evans <randyevans2...@gmail.com>
wrote:

> Todd,
>
> Does it matter where I put the line in the Init_Device procedure?
>
>
> procedure Init_Device;
> begin;
>EZGPIB_BusWriteData(gpib_address,GET_ID);// Get ID of meter
>if EZGPIB_BusWaitForData(gpib_address,meter_id,Timeout) then
> EZGPIB_ScreenWriteLn(meter_id);
>
>EZGPIB_BusWriteData(gpib_address,TRIGGER_SOURCE);// Hold trigger
> until meter can be setup
>EZGPIB_BusWriteData(gpib_address,'INBUF ON');
>EZGPIB_BusWriteData(gpib_address,AUTO_ZERO);
>EZGPIB_BusWriteData(gpib_address,OUTPUT_FORMAT);
> end;
>
>
> Randy
>
> On Sat, Dec 30, 2017 at 11:20 AM, Todd Micallef <tmical...@gmail.com>
> wrote:
>
>> Randy,
>>
>> I am the person that wrote that EzGPIB script. It was my first before I
>> moved on to Python and I have only written a couple for the different
>> meters I have on hand. Version 1.01 is the most current version I have for
>> the 3458A.
>> I see that I should have added at least one more command to the meter
>> initialization.  The additional init command is used in the scripts on
>> xDevs.
>>
>> Add the following line in the Init_Device procedure
>>EZGPIB_BusWriteData(gpib_address,'END ALWAYS');
>>
>> This tells the meter to send an EOI on every read.
>>
>> I am looking for one of my Prologix adapters or I would test this. When I
>> find it, I will also test it. I want to make sure there are no further
>> issues.
>> Also, do both meters run the same firmware versions? I wonder if the HP
>> meter is using a much older version.
>>
>> Todd
>>
>> On Sat, Dec 30, 2017 at 10:42 AM, Randy Evans <randyevans2...@gmail.com>
>> wrote:
>>
>> > Todd,
>> >
>> > I have version 1.01. Yes, please e-mail me your modified version.
>> Maybe it
>> > will help.
>> >
>> > Thanks,
>> >
>> > Randy
>> >
>> > On Sat, Dec 30, 2017 at 4:24 AM, Todd Micallef <tmical...@gmail.com>
>> > wrote:
>> >
>> > > Randy,
>> > >
>> > > Is there a version number at the top of the file? I had two versions
>> > (1.00
>> > > and 1.01). I can't remember all that changed between the two since it
>> has
>> > > been a while but I did find an additional timeout code that limited
>> the
>> > > wait time for reading data to 1 minute. I am guessing I had a problem
>> > with
>> > > mine and added it.
>> > >
>> > > I can email it to you if you want to try it. If it works for you, I
>> will
>> > > have Illya update it on xDevs.
>> > >
>> > > Todd
>> > >
>> > > On Sat, Dec 30, 2017 at 12:39 AM, Randy Evans <
>> randyevans2...@gmail.com>
>> > > wrote:
>> > >
>> > > > I am still unable to get my HP-3458A to work with the xdevs program
>> > > > "HP3458A_Measure_DMM_Noise.488" (https://xdevs.com/article/dmm
>> _noise/
>> > ).
>> > > > It
>> > > > works fine with my Agilent 3458A and with a friend's HP-3458A and
>> his
>> > > > Agilent 3458A using the EZGPIB program.  The SW versions are
>> identical
>> > > with
>> > > > my friend's DMMs, the HP units are (8.2) and with the Agilent units
>> are
>> > > > (9.2).  However, both of my units work fine with the KE5FX GPIB
>> Toolkit
>> > > > HP3458.EXE program to download the NVRAM CAL data.  This would seem
>> to
>> > > > indicate that my HP-3458 GPIB works at least partially.
>> > > >
>> > > > Does anyone have a EZGPIB program that I could try to run (that is
>> > > > different from the Xdev program)?  It would be nice to see if I
>> could
>> > get
>> > > > something to work other than the HP3458.EXE program.  Or if any one
>> has
>> > > > some ideas on what to look for.
>> > > >
>> > > > Thanks,
>> > > >
>> > > > Randy Evans
>> > > >
>> > > > On Tue, Dec 26, 2017 at 7:24 PM, Randy Evans <
>> randyevans2...@gmail.com
>> > >
>> > > > wrote:
>> > > >
>> > > > > I am hoping some of you experts might be able to assist with a
>> > strange
>> > > 

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

Todd,

I have version 1.01. Yes, please e-mail me your modified version.  Maybe it
will help.

Thanks,

Randy

On Sat, Dec 30, 2017 at 4:24 AM, Todd Micallef <tmical...@gmail.com> wrote:

> Randy,
>
> Is there a version number at the top of the file? I had two versions (1.00
> and 1.01). I can't remember all that changed between the two since it has
> been a while but I did find an additional timeout code that limited the
> wait time for reading data to 1 minute. I am guessing I had a problem with
> mine and added it.
>
> I can email it to you if you want to try it. If it works for you, I will
> have Illya update it on xDevs.
>
> Todd
>
> On Sat, Dec 30, 2017 at 12:39 AM, Randy Evans <randyevans2...@gmail.com>
> wrote:
>
> > I am still unable to get my HP-3458A to work with the xdevs program
> > "HP3458A_Measure_DMM_Noise.488" (https://xdevs.com/article/dmm_noise/).
> > It
> > works fine with my Agilent 3458A and with a friend's HP-3458A and his
> > Agilent 3458A using the EZGPIB program.  The SW versions are identical
> with
> > my friend's DMMs, the HP units are (8.2) and with the Agilent units are
> > (9.2).  However, both of my units work fine with the KE5FX GPIB Toolkit
> > HP3458.EXE program to download the NVRAM CAL data.  This would seem to
> > indicate that my HP-3458 GPIB works at least partially.
> >
> > Does anyone have a EZGPIB program that I could try to run (that is
> > different from the Xdev program)?  It would be nice to see if I could get
> > something to work other than the HP3458.EXE program.  Or if any one has
> > some ideas on what to look for.
> >
> > Thanks,
> >
> > Randy Evans
> >
> > On Tue, Dec 26, 2017 at 7:24 PM, Randy Evans <randyevans2...@gmail.com>
> > wrote:
> >
> > > I am hoping some of you experts might be able to assist with a strange
> > > problem i am having trying to make automated measurements using EZGPIB
> > with
> > > an Agilent and an HP 3458A.  I have a program given to me by Martin
> > > Reynolds, which is a variant on the Xdevs noise measurement program.
> > > Martin's program continuously reads the voltage measurements
> sequentially
> > > from the two meters and then stores then in a measurements file, along
> > with
> > > the temperature measurements from both meters.  The program works fine
> on
> > > his Agilent and HP 3458As.
> > >
> > > On my two 3458As, it takes the temperature measurements just fine but
> > only
> > > takes a voltage measurement from the Agilent unit.  The HP unit will
> not
> > > make any voltage measurements although I can see both the 3458As in
> talk
> > > states and, of course, it does sent the temperature measurements.
> > However,
> > > if I turn the HP unit off and then on again, the HP will start to take
> > > voltage and temperature measurements and send them to the PC.
> > >
> > > Any ideas on what might be causing the strange behavior?
> > >
> > > Thanks,
> > >
> > > Randy Evans
> > >
> > ___
> > volt-nuts mailing list -- volt-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/volt-nuts
> > and follow the instructions there.
> >
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] GPIB Issue with 3458A

[Randy Evans]

I am still unable to get my HP-3458A to work with the xdevs program
"HP3458A_Measure_DMM_Noise.488" (https://xdevs.com/article/dmm_noise/).  It
works fine with my Agilent 3458A and with a friend's HP-3458A and his
Agilent 3458A using the EZGPIB program.  The SW versions are identical with
my friend's DMMs, the HP units are (8.2) and with the Agilent units are
(9.2).  However, both of my units work fine with the KE5FX GPIB Toolkit
HP3458.EXE program to download the NVRAM CAL data.  This would seem to
indicate that my HP-3458 GPIB works at least partially.

Does anyone have a EZGPIB program that I could try to run (that is
different from the Xdev program)?  It would be nice to see if I could get
something to work other than the HP3458.EXE program.  Or if any one has
some ideas on what to look for.

Thanks,

Randy Evans

On Tue, Dec 26, 2017 at 7:24 PM, Randy Evans <randyevans2...@gmail.com>
wrote:

> I am hoping some of you experts might be able to assist with a strange
> problem i am having trying to make automated measurements using EZGPIB with
> an Agilent and an HP 3458A.  I have a program given to me by Martin
> Reynolds, which is a variant on the Xdevs noise measurement program.
> Martin's program continuously reads the voltage measurements sequentially
> from the two meters and then stores then in a measurements file, along with
> the temperature measurements from both meters.  The program works fine on
> his Agilent and HP 3458As.
>
> On my two 3458As, it takes the temperature measurements just fine but only
> takes a voltage measurement from the Agilent unit.  The HP unit will not
> make any voltage measurements although I can see both the 3458As in talk
> states and, of course, it does sent the temperature measurements.  However,
> if I turn the HP unit off and then on again, the HP will start to take
> voltage and temperature measurements and send them to the PC.
>
> Any ideas on what might be causing the strange behavior?
>
> Thanks,
>
> Randy Evans
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] GPIB Issue with 3458A

[Randy Evans]

I am hoping some of you experts might be able to assist with a strange
problem i am having trying to make automated measurements using EZGPIB with
an Agilent and an HP 3458A.  I have a program given to me by Martin
Reynolds, which is a variant on the Xdevs noise measurement program.
Martin's program continuously reads the voltage measurements sequentially
from the two meters and then stores then in a measurements file, along with
the temperature measurements from both meters.  The program works fine on
his Agilent and HP 3458As.

On my two 3458As, it takes the temperature measurements just fine but only
takes a voltage measurement from the Agilent unit.  The HP unit will not
make any voltage measurements although I can see both the 3458As in talk
states and, of course, it does sent the temperature measurements.  However,
if I turn the HP unit off and then on again, the HP will start to take
voltage and temperature measurements and send them to the PC.

Any ideas on what might be causing the strange behavior?

Thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Drifting 3458As

[Randy Evans]

I am running the ACAL to check cal constant drift over several times a day
and over a 7 day period (per SN18).  The varying times of the day are to
see how temperature sensitivity affects the cal constant drift since the
room temperature is not constant through the day but is relatively constant
at the same time of day each day; i.e., the furnace is off during the night
so mornings are about 5 degrees C cooler than the afternoon.  Even after
ACAL, I am seeing up to an absolute difference of 3.5 uV on the 732A
voltage reading between the HP and Agilent 3458As, depending on the time of
day.  I suspect the A9 board in the Agilent is the reason since the HP
3458A reads much closer to the 732A value than the Agilent 3458A over
temperature.  Based on long term comparisons with other 732As and a 732B, I
am confident the 732A is stable within 0.1uV.

I am using an ebay A9 board in the Agilent 3458A for the current testing
since I suspect the original A9 board in the Agilent 3458A.  I am
separately testing the original A9 board since I am not completely
confident in the ebay A9 board.  I do not have enough data to draw a
conclusion yet about the original A9 board.  My current concern is to see
if there is agreement that the A9 board is likely the culprit.

Thanks,

Randy Evans

On Fri, Dec 1, 2017 at 1:58 AM, <acb...@gmx.de> wrote:

> What you describe (A9 drift) would be the explanation. However question is
> how much you see. The A9 should not drift much in the intervals you talk
> about (days).
> Also, you should run the ACAL to determine the cal constant not several
> times a day but with several days inbetween, and then divide by number of
> days to determin drift
> Frequent ACAL may not give you good results (random fluctuations such as
> noise, temp... and their impact during cal gets higher the shorter the time
> between ACALs)
>
>
>
> > Gesendet: Donnerstag, 30. November 2017 um 07:40 Uhr
> > Von: "Randy Evans" <randyevans2...@gmail.com>
> > An: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
> > Betreff: [volt-nuts] Drifting 3458As
> >
> > I have been testing two 3458As against a known good Fluke 732A. Each
> 3458A
> > was calibrated for DCV before the start of the measurements so they both
> > started at the same point.   I have been running a series of tests
> > consisting of measuring the Cal Constant as detailed in Service Note 18
> for
> > each meter several times a day (to calculate the drift per the procedure
> in
> > SN 18).  I also measure the 732A voltage in each meter each time using
> NLPC
> > 100 and NRDGS 100 and then recording the STDEV, MEAN, MAX, and MIN
> values.
> > What I have observed is that the Cal Constant is acceptably low but the
> > MEAN value per measurement  is drifting up in one meter and drifting down
> > in the other.   The unit drifting down has a new A3 board installed and
> the
> > unit drifting upward is an Agilent 3458A only a few years old so would
> not
> > be expected to have a drifting A3 board.  It was only calibrated 1 time
> per
> > the internal REV number, so would have likely been re-calibrated if the
> A3
> > board was replaced.
> >
> >
> >  My question is what is the likely cause of the drift in the MEAN voltage
> > reading if the Cal Constant value is relatively constant?  SN 18 says the
> > drift rate of the Cal Constant is an indication of drift in the A3 AD
> > board, but I believe it assumes the A9 voltage ref board has a constant
> > value over time.  If this is not true (e;g., the voltage ref is
> drifting),
> > I think this would explain the drift in the voltage reading even though
> the
> > Cal Constant is relatively constant.  Any opinions on this?
> >
> >
> > Thanks,
> >
> >
> > Randy Evans
> > ___
> > volt-nuts mailing list -- volt-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> > and follow the instructions there.
> >
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Drifting 3458As

[Randy Evans]

I have been testing two 3458As against a known good Fluke 732A. Each 3458A
was calibrated for DCV before the start of the measurements so they both
started at the same point.   I have been running a series of tests
consisting of measuring the Cal Constant as detailed in Service Note 18 for
each meter several times a day (to calculate the drift per the procedure in
SN 18).  I also measure the 732A voltage in each meter each time using NLPC
100 and NRDGS 100 and then recording the STDEV, MEAN, MAX, and MIN values.
What I have observed is that the Cal Constant is acceptably low but the
MEAN value per measurement  is drifting up in one meter and drifting down
in the other.   The unit drifting down has a new A3 board installed and the
unit drifting upward is an Agilent 3458A only a few years old so would not
be expected to have a drifting A3 board.  It was only calibrated 1 time per
the internal REV number, so would have likely been re-calibrated if the A3
board was replaced.


 My question is what is the likely cause of the drift in the MEAN voltage
reading if the Cal Constant value is relatively constant?  SN 18 says the
drift rate of the Cal Constant is an indication of drift in the A3 AD
board, but I believe it assumes the A9 voltage ref board has a constant
value over time.  If this is not true (e;g., the voltage ref is drifting),
I think this would explain the drift in the voltage reading even though the
Cal Constant is relatively constant.  Any opinions on this?


Thanks,


Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Agilent 3458A Issues

[Randy Evans]

Thanks, I see whadt you were saying.

On Nov 23, 2017 8:18 PM, "Illya Tsemenko" <il...@xdevs.com> wrote:

A3 ADC has no way to measure meter's reference drift, as all of the
measurements are relative to A9 output and/or 40k STDR. In this respect ref
output is taken as constant. As result drifty reference will cause all
readings to drift as well after self-calibration, because DC constant is
changed only after external DCV 10V cal. So you have either zero A9 drift
assumed from ACAL DCV or zero drift ADC A3 assumed from CAL 10V. By playing
with time you can narrow the more drifty component. Good stable 3458A
stable to <0.2ppm over week.


On November 24, 2017 9:32:30 AM GMT+08:00, Randy Evans <
randyevans2...@gmail.com> wrote:
>
> Illya,
>
> Can you explain why you say " If ACAL DCV does not remove drift then A3
> is probably fine".  I don't really follow the argument.
>
> Randy
>
> On Thu, Nov 23, 2017 at 5:18 PM, Illya Tsemenko <il...@xdevs.com> wrote:
>
>> Well, one thing you can know for sure , that reference is indeed broken.
>> Drift over a day should be way below the noise floor (<0.1ppm). With 1.7x
>> gain of ADC scale that drift rate gives you around 0.8ppm +/- 0.3ppm due to
>> zener noise. So it is in line of 1.1ppm/day. If ACAL DCV does not remove
>> drift then A3 is probably fine.
>>
>> Since reference is much easier to troubleshoot and fix I would go with
>> replacing LTZ chip and testing if drift go away, if that have any help on
>> your desire to keep meter.
>>
>> Also serial number range in SN doesn't mean much for you, as meter
>> history is unknown and it still may have been serviced at some time.
>>
>> On November 24, 2017 8:40:00 AM GMT+08:00, Randy Evans <
>> randyevans2...@gmail.com> wrote:
>>>
>>> Illya,
>>>
>>> I ran the test you suggested over 4 days and got 7.19114068 VDC on the
>>> start of the test and 7.19113736 VDC at the end of the fourth day (96 hours
>>> later).  I calculate a total of 0.46 ppm drift, which seems excessive but
>>> does not account for the 1.1 ppm/day I measured overall.  I suspect the A3
>>> card is the primary source of drifting.  Since the unit is a late model
>>> Agilent unit, that is well beyond the expected range of units described in
>>> Service Note 18.  What do you think?
>>>
>>> Thanks,
>>>
>>> Randy Evans
>>>
>>> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote:
>>>
>>>> Since you have 732A, testing should be easy enough. Calibrate faulty
>>>> meter for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ
>>>> output. Then leave it running for few days to drift away and calibrate
>>>> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if
>>>> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure
>>>> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used
>>>> directly in the meter, and there are still gain parts to get +12 and
>>>> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same
>>>> (within 0.3ppm) then A9 is fine.
>>>>
>>>>
>>>> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans <
>>>> randyevans2...@gmail.com> wrote:
>>>>>
>>>>> I just received an Agilent 3458A that has a problem with noise and a
>>>>> drifting voltage measurements.  I am using two Fluke 732As to compare
>>>>> absolute voltage measurements over time against the Agilent and an HP
>>>>> 3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
>>>>> low noise, so is being used for comparison.  I have been doing 
>>>>> simultaneous
>>>>> absolute voltage measurements and DC Cal Constant measurements several
>>>>> times a day and then calculating the drift rates of the two units using 
>>>>> the
>>>>> HP Service Note 18 procedure.
>>>>>
>>>>>
>>>>>
>>>>> The results indicate the Cal Constant drift rate of both units is very
>>>>> similar and within spec per Service Note 18.  However, the absolute value
>>>>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the
>>>>> HP unit is within a tenth of a ppm over a day.  In my way of thinking the
>>>>> Cal Constant procedure assumes the voltage reference board in the 3458A is
>>>>> stable, 

Re: [volt-nuts] Agilent 3458A Issues

[Randy Evans]

Illya,

Can you explain why you say " If ACAL DCV does not remove drift then A3 is
probably fine".  I don't really follow the argument.

Randy

On Thu, Nov 23, 2017 at 5:18 PM, Illya Tsemenko <il...@xdevs.com> wrote:

> Well, one thing you can know for sure , that reference is indeed broken.
> Drift over a day should be way below the noise floor (<0.1ppm). With 1.7x
> gain of ADC scale that drift rate gives you around 0.8ppm +/- 0.3ppm due to
> zener noise. So it is in line of 1.1ppm/day. If ACAL DCV does not remove
> drift then A3 is probably fine.
>
> Since reference is much easier to troubleshoot and fix I would go with
> replacing LTZ chip and testing if drift go away, if that have any help on
> your desire to keep meter.
>
> Also serial number range in SN doesn't mean much for you, as meter history
> is unknown and it still may have been serviced at some time.
>
> On November 24, 2017 8:40:00 AM GMT+08:00, Randy Evans <
> randyevans2...@gmail.com> wrote:
>>
>> Illya,
>>
>> I ran the test you suggested over 4 days and got 7.19114068 VDC on the
>> start of the test and 7.19113736 VDC at the end of the fourth day (96 hours
>> later).  I calculate a total of 0.46 ppm drift, which seems excessive but
>> does not account for the 1.1 ppm/day I measured overall.  I suspect the A3
>> card is the primary source of drifting.  Since the unit is a late model
>> Agilent unit, that is well beyond the expected range of units described in
>> Service Note 18.  What do you think?
>>
>> Thanks,
>>
>> Randy Evans
>>
>> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote:
>>
>>> Since you have 732A, testing should be easy enough. Calibrate faulty
>>> meter for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ
>>> output. Then leave it running for few days to drift away and calibrate
>>> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if
>>> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure
>>> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used
>>> directly in the meter, and there are still gain parts to get +12 and
>>> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same
>>> (within 0.3ppm) then A9 is fine.
>>>
>>>
>>> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans <
>>> randyevans2...@gmail.com> wrote:
>>>>
>>>> I just received an Agilent 3458A that has a problem with noise and a
>>>> drifting voltage measurements.  I am using two Fluke 732As to compare
>>>> absolute voltage measurements over time against the Agilent and an HP
>>>> 3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
>>>> low noise, so is being used for comparison.  I have been doing simultaneous
>>>> absolute voltage measurements and DC Cal Constant measurements several
>>>> times a day and then calculating the drift rates of the two units using the
>>>> HP Service Note 18 procedure.
>>>>
>>>>
>>>>
>>>> The results indicate the Cal Constant drift rate of both units is very
>>>> similar and within spec per Service Note 18.  However, the absolute value
>>>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the
>>>> HP unit is within a tenth of a ppm over a day.  In my way of thinking the
>>>> Cal Constant procedure assumes the voltage reference board in the 3458A is
>>>> stable, hence the absolute value reading should remain essentially constant
>>>> after each ACAL DCV, which is the case with the HP unit.  Since the Agilent
>>>> unit shows a steady drift in the absolute reading, this would indicate to
>>>> me that the voltage reference board is likely the cause of the problem, and
>>>> is also likely the cause of the noisy readings.  If so, this is a
>>>> “relatively” easy fix (I have several 3458A voltage reference boards, one
>>>> of which has been continuously powered up for several years).
>>>>
>>>>
>>>>
>>>> The issue is that I have to make a decision to keep or return the Agilent.
>>>> It has a cal seal on it and if I open the unit up to change the voltage
>>>> reference board, I own it and can’t return it.  I would appreciate an
>>>> opinion from the members of the group as to what they think the odds are
>>>> that the voltage reference board is the source of the problems with the
>>>> Agilent 3458A.
>>>>
>>>>
>>>>
>>>> Thanks,
>>>>
>>>>
>>>>
>>>> Randy Evans
>>>>
>>>>
>>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Agilent 3458A Issues

[Randy Evans]

Illya,

I ran the test you suggested over 4 days and got 7.19114068 VDC on the
start of the test and 7.19113736 VDC at the end of the fourth day (96 hours
later).  I calculate a total of 0.46 ppm drift, which seems excessive but
does not account for the 1.1 ppm/day I measured overall.  I suspect the A3
card is the primary source of drifting.  Since the unit is a late model
Agilent unit, that is well beyond the expected range of units described in
Service Note 18.  What do you think?

Thanks,

Randy Evans

On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote:

> Since you have 732A, testing should be easy enough. Calibrate faulty meter
> for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ
> output. Then leave it running for few days to drift away and calibrate
> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if
> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure
> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used
> directly in the meter, and there are still gain parts to get +12 and
> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same
> (within 0.3ppm) then A9 is fine.
>
>
> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans <
> randyevans2...@gmail.com> wrote:
>>
>> I just received an Agilent 3458A that has a problem with noise and a
>> drifting voltage measurements.  I am using two Fluke 732As to compare
>> absolute voltage measurements over time against the Agilent and an HP
>> 3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
>> low noise, so is being used for comparison.  I have been doing simultaneous
>> absolute voltage measurements and DC Cal Constant measurements several
>> times a day and then calculating the drift rates of the two units using the
>> HP Service Note 18 procedure.
>>
>>
>>
>> The results indicate the Cal Constant drift rate of both units is very
>> similar and within spec per Service Note 18.  However, the absolute value
>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the
>> HP unit is within a tenth of a ppm over a day.  In my way of thinking the
>> Cal Constant procedure assumes the voltage reference board in the 3458A is
>> stable, hence the absolute value reading should remain essentially constant
>> after each ACAL DCV, which is the case with the HP unit.  Since the Agilent
>> unit shows a steady drift in the absolute reading, this would indicate to
>> me that the voltage reference board is likely the cause of the problem, and
>> is also likely the cause of the noisy readings.  If so, this is a
>> “relatively” easy fix (I have several 3458A voltage reference boards, one
>> of which has been continuously powered up for several years).
>>
>>
>>
>> The issue is that I have to make a decision to keep or return the Agilent.
>> It has a cal seal on it and if I open the unit up to change the voltage
>> reference board, I own it and can’t return it.  I would appreciate an
>> opinion from the members of the group as to what they think the odds are
>> that the voltage reference board is the source of the problems with the
>> Agilent 3458A.
>>
>>
>>
>> Thanks,
>>
>>
>>
>> Randy Evans
>>
>>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Agilent 3458A Issues

[Randy Evans]

Problem solved!  As expected, operator error.  When I did the CAL 0, I
shorted the voltage and sense lines separately but did not short them
together.  This caused error 209, which caused the CAL 10V to fail since
the zero was not done correctly.  All is well now.  Still learning.

On Sat, Nov 18, 2017 at 12:58 PM, Randy Evans <randyevans2...@gmail.com>
wrote:

> When I try to execute a 10V cal, I get an error code "209 HARDWARE FAILURE
> - - INTERNAL OVERLOAD:31" I suspect that the unit has a different
> security code than 3458.  I can't change it without opening up the unit,
> which I don't want to do unless I decide to keep it.  Do you have any other
> suggestions on how to check the A9 card?
>
> On Sat, Nov 18, 2017 at 11:17 AM, Randy Evans <randyevans2...@gmail.com>
> wrote:
>
>> Illya,
>>
>> That is a great idea.  I will give it a try.
>>
>> Thanks
>>
>> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote:
>>
>>> Since you have 732A, testing should be easy enough. Calibrate faulty
>>> meter for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ
>>> output. Then leave it running for few days to drift away and calibrate
>>> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if
>>> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure
>>> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used
>>> directly in the meter, and there are still gain parts to get +12 and
>>> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same
>>> (within 0.3ppm) then A9 is fine.
>>>
>>>
>>> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans <
>>> randyevans2...@gmail.com> wrote:
>>>>
>>>> I just received an Agilent 3458A that has a problem with noise and a
>>>> drifting voltage measurements.  I am using two Fluke 732As to compare
>>>> absolute voltage measurements over time against the Agilent and an HP
>>>> 3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
>>>> low noise, so is being used for comparison.  I have been doing simultaneous
>>>> absolute voltage measurements and DC Cal Constant measurements several
>>>> times a day and then calculating the drift rates of the two units using the
>>>> HP Service Note 18 procedure.
>>>>
>>>>
>>>>
>>>> The results indicate the Cal Constant drift rate of both units is very
>>>> similar and within spec per Service Note 18.  However, the absolute value
>>>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the
>>>> HP unit is within a tenth of a ppm over a day.  In my way of thinking the
>>>> Cal Constant procedure assumes the voltage reference board in the 3458A is
>>>> stable, hence the absolute value reading should remain essentially constant
>>>> after each ACAL DCV, which is the case with the HP unit.  Since the Agilent
>>>> unit shows a steady drift in the absolute reading, this would indicate to
>>>> me that the voltage reference board is likely the cause of the problem, and
>>>> is also likely the cause of the noisy readings.  If so, this is a
>>>> “relatively” easy fix (I have several 3458A voltage reference boards, one
>>>> of which has been continuously powered up for several years).
>>>>
>>>>
>>>>
>>>> The issue is that I have to make a decision to keep or return the Agilent.
>>>> It has a cal seal on it and if I open the unit up to change the voltage
>>>> reference board, I own it and can’t return it.  I would appreciate an
>>>> opinion from the members of the group as to what they think the odds are
>>>> that the voltage reference board is the source of the problems with the
>>>> Agilent 3458A.
>>>>
>>>>
>>>>
>>>> Thanks,
>>>>
>>>>
>>>>
>>>> Randy Evans
>>>>
>>>>
>>
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Agilent 3458A Issues

[Randy Evans]

When I try to execute a 10V cal, I get an error code "209 HARDWARE FAILURE
- - INTERNAL OVERLOAD:31" I suspect that the unit has a different security
code than 3458.  I can't change it without opening up the unit, which I
don't want to do unless I decide to keep it.  Do you have any other
suggestions on how to check the A9 card?

On Sat, Nov 18, 2017 at 11:17 AM, Randy Evans <randyevans2...@gmail.com>
wrote:

> Illya,
>
> That is a great idea.  I will give it a try.
>
> Thanks
>
> On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote:
>
>> Since you have 732A, testing should be easy enough. Calibrate faulty
>> meter for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ
>> output. Then leave it running for few days to drift away and calibrate
>> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if
>> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure
>> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used
>> directly in the meter, and there are still gain parts to get +12 and
>> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same
>> (within 0.3ppm) then A9 is fine.
>>
>>
>> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans <
>> randyevans2...@gmail.com> wrote:
>>>
>>> I just received an Agilent 3458A that has a problem with noise and a
>>> drifting voltage measurements.  I am using two Fluke 732As to compare
>>> absolute voltage measurements over time against the Agilent and an HP
>>> 3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
>>> low noise, so is being used for comparison.  I have been doing simultaneous
>>> absolute voltage measurements and DC Cal Constant measurements several
>>> times a day and then calculating the drift rates of the two units using the
>>> HP Service Note 18 procedure.
>>>
>>>
>>>
>>> The results indicate the Cal Constant drift rate of both units is very
>>> similar and within spec per Service Note 18.  However, the absolute value
>>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the
>>> HP unit is within a tenth of a ppm over a day.  In my way of thinking the
>>> Cal Constant procedure assumes the voltage reference board in the 3458A is
>>> stable, hence the absolute value reading should remain essentially constant
>>> after each ACAL DCV, which is the case with the HP unit.  Since the Agilent
>>> unit shows a steady drift in the absolute reading, this would indicate to
>>> me that the voltage reference board is likely the cause of the problem, and
>>> is also likely the cause of the noisy readings.  If so, this is a
>>> “relatively” easy fix (I have several 3458A voltage reference boards, one
>>> of which has been continuously powered up for several years).
>>>
>>>
>>>
>>> The issue is that I have to make a decision to keep or return the Agilent.
>>> It has a cal seal on it and if I open the unit up to change the voltage
>>> reference board, I own it and can’t return it.  I would appreciate an
>>> opinion from the members of the group as to what they think the odds are
>>> that the voltage reference board is the source of the problems with the
>>> Agilent 3458A.
>>>
>>>
>>>
>>> Thanks,
>>>
>>>
>>>
>>> Randy Evans
>>>
>>>
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Agilent 3458A Issues

[Randy Evans]

Illya,

That is a great idea.  I will give it a try.

Thanks

On Sat, Nov 18, 2017 at 4:47 AM, Illya Tsemenko <il...@xdevs.com> wrote:

> Since you have 732A, testing should be easy enough. Calibrate faulty meter
> for zero and DCV 10V to 732A, record CAL? 2,1 value. This is your LTZ
> output. Then leave it running for few days to drift away and calibrate
> again to same 732A. Check CAL? 2,1 again. Calculate the difference and if
> it matches output drift (that 1.1ppm/day you mention) - you can be 80% sure
> that A9 is a problem. Other 19% go to A1 and A3 circuits, as 7V is not used
> directly in the meter, and there are still gain parts to get +12 and
> -12VREF on A3 and 10Vish bipolar levels on A1. If your CAL? 2,1 stays same
> (within 0.3ppm) then A9 is fine.
>
>
> On November 18, 2017 12:59:53 PM GMT+08:00, Randy Evans <
> randyevans2...@gmail.com> wrote:
>>
>> I just received an Agilent 3458A that has a problem with noise and a
>> drifting voltage measurements.  I am using two Fluke 732As to compare
>> absolute voltage measurements over time against the Agilent and an HP
>> 3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
>> low noise, so is being used for comparison.  I have been doing simultaneous
>> absolute voltage measurements and DC Cal Constant measurements several
>> times a day and then calculating the drift rates of the two units using the
>> HP Service Note 18 procedure.
>>
>>
>>
>> The results indicate the Cal Constant drift rate of both units is very
>> similar and within spec per Service Note 18.  However, the absolute value
>> measurements show the Agilent unit changing 1.1 ppm over a day whereas the
>> HP unit is within a tenth of a ppm over a day.  In my way of thinking the
>> Cal Constant procedure assumes the voltage reference board in the 3458A is
>> stable, hence the absolute value reading should remain essentially constant
>> after each ACAL DCV, which is the case with the HP unit.  Since the Agilent
>> unit shows a steady drift in the absolute reading, this would indicate to
>> me that the voltage reference board is likely the cause of the problem, and
>> is also likely the cause of the noisy readings.  If so, this is a
>> “relatively” easy fix (I have several 3458A voltage reference boards, one
>> of which has been continuously powered up for several years).
>>
>>
>>
>> The issue is that I have to make a decision to keep or return the Agilent.
>> It has a cal seal on it and if I open the unit up to change the voltage
>> reference board, I own it and can’t return it.  I would appreciate an
>> opinion from the members of the group as to what they think the odds are
>> that the voltage reference board is the source of the problems with the
>> Agilent 3458A.
>>
>>
>>
>> Thanks,
>>
>>
>>
>> Randy Evans
>>
>>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Agilent 3458A Issues

[Randy Evans]

I just received an Agilent 3458A that has a problem with noise and a
drifting voltage measurements.  I am using two Fluke 732As to compare
absolute voltage measurements over time against the Agilent and an HP
3458A.  The HP unit has a new A3 ADC card and seems to be very stable and
low noise, so is being used for comparison.  I have been doing simultaneous
absolute voltage measurements and DC Cal Constant measurements several
times a day and then calculating the drift rates of the two units using the
HP Service Note 18 procedure.



The results indicate the Cal Constant drift rate of both units is very
similar and within spec per Service Note 18.  However, the absolute value
measurements show the Agilent unit changing 1.1 ppm over a day whereas the
HP unit is within a tenth of a ppm over a day.  In my way of thinking the
Cal Constant procedure assumes the voltage reference board in the 3458A is
stable, hence the absolute value reading should remain essentially constant
after each ACAL DCV, which is the case with the HP unit.  Since the Agilent
unit shows a steady drift in the absolute reading, this would indicate to
me that the voltage reference board is likely the cause of the problem, and
is also likely the cause of the noisy readings.  If so, this is a
“relatively” easy fix (I have several 3458A voltage reference boards, one
of which has been continuously powered up for several years).



The issue is that I have to make a decision to keep or return the Agilent.
It has a cal seal on it and if I open the unit up to change the voltage
reference board, I own it and can’t return it.  I would appreciate an
opinion from the members of the group as to what they think the odds are
that the voltage reference board is the source of the problems with the
Agilent 3458A.



Thanks,



Randy Evans


HP-3458A Calibration drift rate 2017-11-17A.xlsx
Description: MS-Excel 2007 spreadsheet
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-3458A NVRAM

[Randy Evans]

Frank,

Thanks for the information.  I was hoping to hear from someone that had
actually successfully used the DS1220AD in the 3458A.  I did not understand
the comment about the "instrument of 'quarks'", but it may be in regards to
the second set of DS1230Y NVRAMs?  Did you change those out to DS1230AD
NVRAMS also?

Thanks,

Randy

On Sat, Nov 11, 2017 at 6:31 AM, Dr. Frank 
wrote:

> Hello Randy,
>
> I have replaced the CAL-nvRAM by a DS1220AD-150 in 2013, as the Y version
> was not available.
>
> The speed was not the problem, but a slightly different supply volatge
> range, if I remeber correctly.
>
> My 3458A works w/o any problem, as does the instruments of 'quarks', who
> got the 2nd nvRAM which I have ordered.
>
> Frank
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-3458A NVRAM

[Randy Evans]

Actually, it could make a difference depending on when the processor tries
to access the memory on start up.  The Maxim app note mentions that many
legacy programs designed for the DS1220Y may not work with the DS122AD,
hence the reason for the question.  I really would like to hear from
someone that has actually successfully replaced the DS1220Y with the
DS1220AD, since the DS1220Y is no longer avaialble..

On Fri, Nov 10, 2017 at 5:20 AM, Poul-Henning Kamp <p...@phk.freebsd.dk>
wrote:

> 
> In message <CANwu9JbdybQPrSOrQn6xRM0M5YpaL2t40i33+bZMJcDJjO=fqg@mail.
> gmail.com>
> , Randy Evans writes:
>
> >Does anyone know if the DS1220AD will work as a direct replacement for
> >the DS1220Y
> >NVRAM chip currently installed in the HP-3458A?  There is a timing
> >difference between the two devices, as explained in Maxim AN 202.
>
> I don't think that difference will make any difference.
>
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] HP-3458A NVRAM

[Randy Evans]

Does anyone know if the DS1220AD will work as a direct replacement for
the DS1220Y
NVRAM chip currently installed in the HP-3458A?  There is a timing
difference between the two devices, as explained in Maxim AN 202.

"the "Y" parts had a reset timeout on the order of milliseconds while the
"AD"
parts have a timeout of 125ms. When replacing the Y part with the AD part,
it must be determined that
the controlling processor does not become active during a power-up cycle
for at least 125ms to ensure
that the NV SRAM is available before the processor attempts a memory
access."

There have been documented cases where the new DS1220AD part will not work
in circuits designed with the DS1220Y (now discontinued).

I would like to know if anyone has successfully utilized the DS1220AD
before proceeding to buy the parts.  Similar question for the DS1230Y and
DS1230AD.

Thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Banana jack shorting straps

[Randy Evans]

I believe that the Fluke shorting system has 3/4" spacing both vertically
and horizontally, which is not compatible with the 3458 (I couldn't find a
spec but visually it looks identically in both dimensions in the photos).
The 3458 spacing is slightly greater than 3/4' horizontally.

On Thu, Nov 9, 2017 at 10:14 AM, Rob Klein  wrote:

> You gentlemen are aware that these things are available from Fluke at a
> fairly reasonable price?
>
> http://nl.farnell.com/fluke/fluke-884x-short/lead-test-4-
> wire-fluke-884x-short/dp/1274092
>
>
> ⁣Met vriendelijke groet,
> Rob Klein
>
> verstuurd vanaf mijn smartphone​
>
> Op 9 nov. 2017 14:12, om 14:12, "David C. Partridge" <
> david.partri...@perdrix.co.uk> schreef:
> >Mark
> >
> >I'm trying to imagine what you are describing - is this PCBs with 4mm
> >banana plugs installed or a small PCB with two slots at 3/4" centres to
> >match the socket spacing?
> >
> >If the latter is this intended to cover just two sockets or to short
> >all four Force and Sense sockets together (if arranged like a 3458A)?
> >
> >Thanks
> >Dave
> >
> >-Original Message-
> >From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Mark
> >Sims
> >Sent: 09 November 2017 02:14
> >To: volt-nuts@febo.com
> >Subject: [volt-nuts] Banana jack shorting straps
> >
> >The main use of these would be shorting sense to drive jacks.  They
> >could also be used for input shorts.  The advantage over bare copper
> >would be the ENIG gold finish... bare copper quickly forms oxide layers
> >and copper oxide has a horrible thermal EMF.  Granted, ENIG gold
> >basically involves waving a bar of gold over the plating tank and
> >hoping some gold atoms fall off.  The board house I use deposits a
> >thicker layer than most.   You don't want to know what "hard gold"
> >finish would cost.
> >
> >Using a PCB house to fab them is probably 20 times less expensive than
> >having a machine shop do them out of solid copper... maybe 50 times
> >less if you need to get them gold plated.
> >___
> >volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to
> >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> >and follow the instructions there.
> >
> >___
> >volt-nuts mailing list -- volt-nuts@febo.com
> >To unsubscribe, go to
> >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> >and follow the instructions there.
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] EPROM Programmer

[Randy Evans]

Can someone recommend a good low-cost method to program the DS1220 and
DS1230 NVRAMs for the HP-3458A?  I downloaded the CAL contents and I need
to program new NVRAM chips to replace the older (very old) NVRAMs still in
the unit.

Also, will the DS1220AD and DS1230AD chips work in place of the
existing DS1220Y
and DS1230Y NVRAMs in the HP-3458A?  The AD versions have different timing
"power good" specifications and they don't work as a plug-in substitute in
all cases.  I assume some 3458A users have changed out the NVRAMs with the
new Dallas parts ( Dallas no longer makes the DS1230Y NVRAM, but does still
make the DS1230Y NVRAM, according to their data sheet).

Thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Prema 6048 Cal switch confusion

[Randy Evans]

Dave,

Note the following from Maxim AN 202:

I Replaced My Standard SRAM with an NV SRAM and Now My
System Doesn't Work at All. What Caused This?

In general, this is caused by one of two things:
First, the designer may not have considered the recovery time, or tREC, of
the particular NV SRAM
selected. On power-up, an internal power monitor disables the NV SRAM until
a power-good situation
and then holds it disabled for an additional 2ms (max) or 125ms (max),
depending on the NV SRAM
Page 5 of 9

after power-good. If the microcontroller attempts to access the memory
before tREC times out, it will not
be able to access the device's memory to read or write, so the system
fails. Either a software loop on
power-up to extend the access time past tREC, or moving the NV SRAM access
somewhere later in the
power-on initialization sequence in the microcontroller's firmware will
resolve the problem. This problem
often can be corrected by selecting a CPU supervisor that has a reset time
longer than the recovery time
of the NV SRAM.

Second, selecting the voltage levels at which the NV SRAM and the
microcontroller become active is
critical. If the microcontroller becomes active below 4.5V, and the NV SRAM
becomes active above
4.75V, the same problem of the microcontroller trying to access a disabled
NV SRAM occurs. The
power-good threshold for the two devices should force the system to enable
the NV SRAM first and then
the processor. This involves selecting the NV SRAM with the appropriate
power-good level and pairing
that with a CPU supervisor that enables the processor at a higher voltage.

Some NV SRAMs have an active-low RESET output that is synchronous with its
own internal reset. If
this is used to reset the microcontroller, the possibility of trying to
access a disabled NV SRAM is
removed.

and:

Are Any NV SRAMs Not Recommended for Future Designs?

Yes. The DS1220Y and DS1225Y are not recommended for new designs. These
older devices used a
battery reference to determine the power-valid trip-point during power
cycles. Newer designs use a band
gap reference. The battery-referenced devices had a trip point that
decreased during the life of the
device. Devices using the band gap have a trip point that is stable for the
life of the product.

The DS1220AD and DS1225AD are recommended for new designs needing the
functionality of a 16kb
or 64kb NV SRAM. For existing designs, the DS1220AD or DS1225AD may be
considered as
replacements; however, the "Y" parts had a reset timeout on the order of
milliseconds while the "AD"
parts have a timeout of 125ms. When replacing the Y part with the AD part,
it must be determined that
the controlling processor does not become active during a power-up cycle
for at least 125ms to ensure
that the NV SRAM is available before the processor attempts a memory access.

Randy Evans

On Fri, Nov 3, 2017 at 2:54 AM, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:

> This gets odder and odder.   I put the new DS1220AD into the burner and
> read it.   Pretty random rubbish.
>
> So I cleared it to all FF and inserted into the meter set to Cal mode and
> powered on - it apparently copied the default Cal constants to the NVRAM.
>
> However when I took it out again and looked at the content it didn't look
> anything like what I'd read from the original NVRAM, and was mostly still
> x'FF' but with blocks of ten bytes of zeros at x'100' boundaries, followed
> by zeroes starting at x'6C7' to x'7ef' and what looks like a checksum at
> x'7f0'.   I can't believe that these are cal constants specific to this
> meter!  Though they might be a set of default constants for any 6048!
>
> Filling it with all 00 resulted in an Error 8 (Checksum failure).
>
> I then programmed it with the data I had read from the DS1220Y (and had
> verified).   That also gave an Error 8.
>
> The data I read is attached in Intel Hex format.
>
> I'm wonder whether the meter is failing to read the original NVRAM in a
> way that somehow passes checksumming
>
> Dave
> -Original Message-
> From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Tom
> Miller
> Sent: 02 November 2017 19:05
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Prema 6048 Cal switch confusion
>
> How about copying the contents of the old nvram to the new one?
>
>
> - Original Message -
> From: "David C. Partridge" <david.partri...@perdrix.co.uk>
> To: "'Discussion of precise voltage measurement'" <volt-nuts@febo.com>
> Sent: Thursday, November 02, 2017 2:58 PM
> Subject: Re: [volt-nuts] Prema 6048 Cal switch confusion
>
>
> > Update - when I tried this I was using a brand new DS1220AD-100IND
> (blank)
> > to replace the DS1220Y.
> >
> > Reinstalling the DS1220Y and it worked as exp

Re: [volt-nuts] FS: Keithley 2000 6 1/2 Digit DMM

[Randy Evans]

Bob,

I am interested in the Keithley if it is still available.

Thanks,

Randy Evans

On Thu, May 4, 2017 at 1:09 PM, Four Designs Company <
fourdesi...@comcast.net> wrote:

> Greetings all:
>
> I am offering a Keithley 2000 6-1/2 digit DMM for sale. This instrument is
> from my lab, now surplus to need. I have installed a new VFD, and adjusted
> it using my 4800A, non certified.
> Looks good, and works perfectly. Comes with new test leads, power cord,
> and manuals on CD. It has the bench kit; ie, handle and feet.
>
> $425 shipped CONUS PayPal is fine.   Pictures on request.
>
> Email with any questions.
> Thanks for the bandwidth.
>
> Bob
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Fluke 887 mod with LTC1050

[Randy Evans]

Frank,

The 8 pA bias current is well within the spec for the LTC1050 (+-10pA
typical, worst case +-50pA at 25C) but I was surprised about the lack of
variation. I also tried an "air bridge" wiring from the 887 filter to the
LTC1050 to avoid any leakage of the circuit board.  It made no difference,
essentially eliminating board leakage.  It could still be switch leakage.
Eventually I plan on just [putting a 1 megohm resistor from the LTC1050
positive input to ground and see if I still see the 8pA leakage.  If I do,
then it's definitely the IC and not the switches.

Randy

On Sat, Apr 29, 2017 at 3:59 AM, Frank Stellmach  wrote:

> Randy,
>
> 8pA is quite good a leakage / bias current for such a differential VM, and
> also for the LT1050.
>
> What makes me wonder, why three different OpAmps should all have exactly
> -8pA.
>
> The variation from one OpAmp to the others should vary greatly, even if
> these are from the same batch.
>
> I don't remember your circuit, but maybe you have some sort of input
> protection on the non-inverting input, and that may cause this constant
> bias. Have you assembled the OpAmp completely on the PCB, or is the + input
> air-wired to the polarity switch S4E ? Ordinary PCB material may also cause
> leakage currents.
>
> I would also check the switches, if they are contaminated.
>
> Frank
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Fluke 887 mod with LTC1050

[Randy Evans]

It looks like a better candidate would be the LTC2054, which has a typical
bias current of 1 pA at 25C and is essentially constant up to 45C.

Randy

On Thu, Apr 27, 2017 at 5:02 PM, Randy Evans <randyevans2...@gmail.com>
wrote:

> Charles,
>
> You are absolutely correct.  I misread the data sheet.  It's interesting
> that all three LTC1050s behave exactly the same. They have the same lot
> code number.but I would expect more variation.  Live an learn.
>
> Randy
>
> On Thu, Apr 27, 2017 at 12:18 PM, Charles Steinmetz <csteinm...@yandex.com
> > wrote:
>
>> Randy wrote:
>>
>>  but I recently noticed the meter reads -0.08 when the
>>>  input is open on the 1V range and the null switch is on 0.0001
>>>  This equates to a -8uV reading.
>>>  I believe this is due to the input bias current of the LTC1050
>>>*   *   *
>>>  However, this would imply an 8pA bias current,
>>>  which is much higher than expected.
>>>
>>
>> I am attaching the relevant portion of the LTC1050 datasheet.  Note that
>> at 25C, the 1050 has an input offset current spec of +/- 20pA (both typical
>> -- max is ~5x worse).  I would expect a total input offset of +/- 20uV
>> (typical) in your circuit.  (The 0.5uV typical input offset voltage is not
>> a significant contributor in this context.)
>>
>> Best regards
>>
>> Charles
>>
>>
>>
>> ___
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/volt-nuts
>> and follow the instructions there.
>>
>
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Fluke 887 mod with LTC1050

[Randy Evans]

Charles,

You are absolutely correct.  I misread the data sheet.  It's interesting
that all three LTC1050s behave exactly the same. They have the same lot
code number.but I would expect more variation.  Live an learn.

Randy

On Thu, Apr 27, 2017 at 12:18 PM, Charles Steinmetz 
wrote:

> Randy wrote:
>
>  but I recently noticed the meter reads -0.08 when the
>>  input is open on the 1V range and the null switch is on 0.0001
>>  This equates to a -8uV reading.
>>  I believe this is due to the input bias current of the LTC1050
>>*   *   *
>>  However, this would imply an 8pA bias current,
>>  which is much higher than expected.
>>
>
> I am attaching the relevant portion of the LTC1050 datasheet.  Note that
> at 25C, the 1050 has an input offset current spec of +/- 20pA (both typical
> -- max is ~5x worse).  I would expect a total input offset of +/- 20uV
> (typical) in your circuit.  (The 0.5uV typical input offset voltage is not
> a significant contributor in this context.)
>
> Best regards
>
> Charles
>
>
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Fluke 887 mod with LTC1050

[Randy Evans]

Some time ago I presented a design where I replaced the non-working chopper
circuitry for a Fluke 887 differential voltmeter with an LTC1050 precision
chopper amplifier.  The design seemed to work fine, but I have discovered
an issue ( I haven’t actually used the meter very much).  The manual says
to zero the meter by shorting the input terminals and then adjusting the
zero adjustment for a zero reading on the meter.  This works fine with the
LTC1050 circuit, but I recently noticed the meter reads -0.08 when the
input is open on the 1V range and the null switch is on 0.0001 (it is fine
on all other ranges/null switch settings).  This equates to a -8uV
reading.  I believe this is due to the input bias current of the LTC1050
and the 1 megohm input resistance of the 887 on the most sensitive
range/null setting.  I tried three different LTC1050s and they all exhibit
the same problem.

However, this would imply an 8pA bias current, which is much higher than
expected.  My question is: does anyone else have a better explanation for
this issue and does anyone experience this issue with the original circuit?



Thanks,

Randy Evans AE6YG
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Short term "standard" cell?

[Randy Evans]

FYI, I bought two of these used 3458A reference boards for $85 each a few
years ago and they both experience noise bursts.  I plan on replacing the
LTZ1000 chips on them (sometime in the near future).

Randy Evans
AE6YG

On Sun, Mar 12, 2017 at 10:53 AM, m k <m1k...@hotmail.com> wrote:

>
>
> On 12/03/17 17:27, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> > On Sun, 12 Mar 2017 at 17:03, Frank Stellmach <
> frank.stellm...@freenet.de>
> > wrote:
> >
> >> Hi Chris,
> >>
> >>
> >>
> >> Therefore,  instead of poking around with these mediocre 10V
> >> "references", I'd look for a possibility to get access to a 3458A, maybe
> >> there's a friendly volt-nuts nearby.
> >>
> >> Frank
> >>
> > There are a number of reference boards supposedly removed from 3458As on
> > eBay. Assuming they are non counterfeit (not necessarily a valid
> assumption
> > for items on eBay), how easy would they be to integrate into a box to
> make
> > a stable reference?
> >
> > The LTZ1000A chip is about $50 new, but to make a stable reference you
> need
> > quite expensive resistors, so a used 3458A reference is attractive. But I
> > don't know if problems making low thermal EMF joints might totally ruin
> the
> > potential performance.
> >
> >
> >
> >
> The suspicion is that they may be genuine, but were rejects because of
> noise bursts. I bought one a while ago, but still not sure of its long term
> stability.
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] PCB Artist

[Randy Evans]

KiCad looks very good and I downloaded it to try it out.  However, does
anyone have a good, low-cost PCB fab house to recommend?  I am designing a
voltage reference programmable fro 0 to 10 volts with a LTZ1000 reference
and settabiltiy of 0.1ppm and I need a PCB fabbed.

Thanks,

Randy Evans AE6YG

On Tue, Dec 13, 2016 at 5:22 AM, Herbert Poetzl <herb...@13thfloor.at>
wrote:

> On Mon, Dec 12, 2016 at 04:39:36PM -0800, Randy Evans wrote:
> > Does anyone have experience with PCBArtist?
>
> Sorry, no PCBArtist experience here.
>
> > It looks pretty good for 2-layer board up to 60
> > in^2 for $33 but I have no experience with it.
>
> > I was looking at Eagle PCB but it's pretty expensive
> > for a 4-layer capability version.
>
> A litte apples and oranges here :)
>
> The Eagle Light version can be used for free for
> non-profit purposes and works for up to 4x3.2inch
> with two layers.
>
> If you don't have any personal preference, then
> KiCad is definitely the way to go. It has improved
> dramatically since it got the CERN treatment and
> doesn't cost a cent regardless of size and layers.
>
> Best,
> Herbert
>
> > Thanks,
>
> > Randy Evans AE6YG
> > ___
> > volt-nuts mailing list -- volt-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> > and follow the instructions there.
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] LTZ1000 project build

[Randy Evans]

Illya,

Very interesting.  The temco/stability data  does not plot but the X-Y
format seems to be OK.  Is it supposed to plot or do I have to plot it
myself with the csv data?

Thanks,

Randy Evans

On Thu, May 26, 2016 at 3:42 AM, Illya Tsemenko <il...@xdevs.com> wrote:

> I'm glad my little project got so much attention. Worth to mention few
> points regarding my (or any other LTZ1000) unit:
>
> A. One should consider cost of whole BOM, not only LTZ chip. In my case
> resistors from VPG exceed cost of LTZ1000 by far.
> B. PCB I designed was targeted best to my own application need, where
> compact size and direct output (whatever is coming out of LTZ) were key
> importance. Since modules are part of bigger system with DAC synth,
> specific value, like 7.150 was not important for me.
> C. If there is large enough group to have this project going, I can
> actually modify original design (e.g. for easier hand soldering, or added
> buffer or ratio circuits, onboard LDO, you name it) and get PCBs made for
> interested nuts, at small cost.
>
> You can also find lot of temco/stability data with temperature/environment
> logs with mentioned LTZ modules on my site here:
> https://xdevs.com/services/ in LTZ1000 voltage reference tests section.
> RAW DSV data are available. I still have 3 modules at hand for any
> testing/checks (one was sold while ago, one was installed in HP 3245A
> source to replace LM399).
>
> Illya "TiN" Tsemenko
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Retiring collection of 6/7 dial bridges

[Randy Evans]

I live locally and I am interested in the items.  Do you have a complete
list available?

Randy Evans
On Apr 9, 2016 9:34 PM, "Demian Martin" <demianm@gmail.com> wrote:

> I have a number of precision bridges and the like that I really need to
> move
> on to a new home. Is there anyone local to me who is interested?
>
> JRL KV bridge
>
> Fluke Lead Compensator
>
> Fluke Reference divider
>
> Honeywell potentiometer
>
> HF impedance bridge
>
> and some other stuff.
>
>
>
> Demian Martin
>
> Product Design Services
>
> San Leandro, CA 94577
>
>
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] ADA4522

[Randy Evans]

I would use a filter such as TI's SBVA010 app note, "Improved Voltage
reference Filter has Several Advanatages" or the article by Walt Jung,
"Build an Ultra-Low Noise Voltage Reference" in Electronic Design.

On Fri, Apr 8, 2016 at 1:02 AM, <acb...@gmx.de> wrote:

> Low frequency noise is very good, but is is high noise at about 800kHz
> (chopper) and above (possible artifacts). That should be filtered,
> depending on your application.
> What did you foresee to get rid of it, or would you accept it? Simple RC
> filter as indicated in the manual increases the output resistance.
>
>
>
>
> > Gesendet: Freitag, 08. April 2016 um 03:35 Uhr
> > Von: "Randy Evans" <randyevans2...@gmail.com>
> > An: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
> > Betreff: Re: [volt-nuts] ADA4522
> >
> > Sure, all good applications.  I am thinking of using it as an output
> filter
> > for a 10V reference to filter all noise above 10Hz,
> >
> > On Thu, Apr 7, 2016 at 6:27 PM, Daniel Mendes <dmend...@gmail.com>
> wrote:
> >
> > > Ada4522-2 and 4522-4 are stocked at mouser. What about summing all
> outputs
> > > to reduce noise? Or use as buffered outputs with good reverse
> isolation...
> > >
> > > Daniel
> > > Em 07/04/2016 13:31, "Randy Evans" <randyevans2...@gmail.com>
> escreveu:
> > >
> > > > Has anyone looked at the ADA4522 precision op amp from Analog
> Devices.
> > > It
> > > > looks very intriguing with it's extremely low offset voltage drift
> of 22
> > > > nV/°C maximum.  The offset voltage is as high as 5 uV but this could
> be
> > > > nulled out and it should be very stable over temperature after
> that.  It
> > > > could be a great choice for a voltage reference circuit.  Looks quite
> > > > inexpensive also, although AD only sell in tubes of 96 right now.
> > > > ___
> > > > volt-nuts mailing list -- volt-nuts@febo.com
> > > > To unsubscribe, go to
> > > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> > > > and follow the instructions there.
> > > >
> > > ___
> > > volt-nuts mailing list -- volt-nuts@febo.com
> > > To unsubscribe, go to
> > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> > > and follow the instructions there.
> > >
> > ___
> > volt-nuts mailing list -- volt-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> > and follow the instructions there.
> >
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] ADA4522

[Randy Evans]

Has anyone looked at the ADA4522 precision op amp from Analog Devices.  It
looks very intriguing with it's extremely low offset voltage drift of 22
nV/°C maximum.  The offset voltage is as high as 5 uV but this could be
nulled out and it should be very stable over temperature after that.  It
could be a great choice for a voltage reference circuit.  Looks quite
inexpensive also, although AD only sell in tubes of 96 right now.
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] volt-nuts Digest, Vol 77, Issue 15

[Randy Evans]

Willy,

Where are you located?

Randy Evans
AE6YG

On Sun, Jan 31, 2016 at 11:49 AM, new <pit...@williams-net.com> wrote:

> I'm thinking of doing non-commercial 'calibrations' for
> folks like us volt-nuts.
>
>  Since I have three 3458s, three 732As, a 732b, a 4214,
> an sr104, a 4210, all NIST cal'ed and I could do front-panel
> adjustments for the 3457.
>
>  Would anyone here like to do that? I would start by
> replacing the cal battery, too.
>
>   I could give the 'as found' and 'as left' numbers too,
> for the meters that arrived with 'alive' batteries.
>
>  Probably best to do it on fleabay to protect everyone
> involved.
>
>  If this post is a violation of volt-nuts policy, please take it down!
>
> Willy
>
>
>
> On 1/31/2016 12:00 PM, volt-nuts-requ...@febo.com wrote:
>
>> Send volt-nuts mailing list submissions to
>> volt-nuts@febo.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> or, via email, send a message with subject or body 'help' to
>> volt-nuts-requ...@febo.com
>>
>> You can reach the person managing the list at
>> volt-nuts-ow...@febo.com
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of volt-nuts digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: 3457A - should I preserve SRAM contents, or purposely
>>corrupt them by removing power?
>>(Dr. David Kirkby (Kirkby Microwave Ltd))
>>
>>
>> --
>>
>> Message: 1
>> Date: Sun, 31 Jan 2016 10:54:10 +
>> From: "Dr. David Kirkby (Kirkby Microwave Ltd)"
>> <drkir...@kirkbymicrowave.co.uk>
>> To: Discussion of precise voltage measurement <volt-nuts@febo.com>
>> Subject: Re: [volt-nuts] 3457A - should I preserve SRAM contents, or
>> purposely corrupt them by removing power?
>> Message-ID:
>> <
>> canx10hcqoek9n+a0pinrzdzvc3b4d7twyztkuzvx_n9nmwc...@mail.gmail.com>
>> Content-Type: text/plain; charset=UTF-8
>>
>> On 25 January 2016 at 11:12, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> drkir...@kirkbymicrowave.co.uk> wrote:
>>
>> As noted in another thread, I want to replace a battery in a 3457A that
>>> has not been replaced in at least 11 years. The instrument has not been
>>> calibrated in that time either. At the time it was purchased from a
>>> dealer,
>>> I was told it was within specification, but if I wanted it calibrated I
>>> would need to pay. I never did have it calibrated, so have no historical
>>> data about this. I've no idea when it was calibrated, and have no cal
>>> certificate, so have no idea of the errors at the time of calibration.
>>>
>>> I now want to change the battery, *and* send it to Keysight for
>>> calibration - I have a healthy skepticism of 3rd party labs, so would
>>> rather pay more and get the job done by Keysight.
>>>
>>> I'm wondering if I would be better purposely removing the battery, and
>>> putting a short across the SRAM so I ensure the contents are definitely
>>> lost. My logic is that
>>>
>>> 1) If I send it to Keysight and the cal data is corrupt, they will set
>>> the
>>> meter correct.
>>>
>>> 2) If sent to Keysight, with the cal data in tact, then if its within
>>> specification they will not adjust it. So if the limit on some parameter
>>> is
>>> 1%, and the error is 0.5%, then it will not be adjusted. But if the SRAM
>>> is
>>> corrupted, the error will be huge (if it will read at all), so it would
>>> force Keysight to adjust it to the correct value.
>>>
>>>
>>
>> At that point the error should be effectively zero
>>>
>>> 
>>
>> Thoughts?
>>>
>>> Someone sent me a private email, saying that if by purposely removed the
>> power from the SRAM  caused the 3457A to fail its self-tests, which is may
>> well do, then Keysight may consider the 3457A needs repair, and so offer a
>> fixed-price repair. Hence my "trick" to get this calibrated as accurately
>> as possible would have backfired, and I'd be out of pocket. In fact, on a
>> 3457A, the fixed-price-repair would probably cost more than the instrument
>> is worth, as these are not worth a lot now.
>>
>> Hence I would not do this before getting clarifica

Re: [volt-nuts] 3458A Zero reading

[Randy Evans]

I used a 12 AWG wire formed into a U shape for the short and the zero
voltage measured less than 0.2 uV after a good 2+ hour warmup.  However, I
am seeing drifts of several uV for the 752 calibration.  I was using TV
twin lead to connect the 732 to 752 and 752 to 3458A since that's really
all I have for now.  I suspect thermals are killing me so I need to find
some low thermal shielded differential cable to connect from the 752 to the
3458A.  I did not see anything like that in Pomona's arsenal.  I was
thinking about Bill Gold's idea of making my own but I think it would end
up being \very stiff.  Any other ideas for a good source of shielded copper
wire twinax?

Randy AE6YG

On Mon, Jul 27, 2015 at 4:10 PM, J M via volt-nuts volt-nuts@febo.com
wrote:

 I use a 8 oz styrofoam cup to isolate air currents around the 3458A
 terminals when zeroing with shorting bar


 Sent from my 20 Texas sized
 iPhone


  On Jul 27, 2015, at 2:57 PM, Richard Moore richiem5...@gmail.com
 wrote:
 
 
  Randy — My 3458A manual specs 12 or 14 gauge solid copper wire for the
 short, bunt in to a U shape. I use 14 gauge. Poul-Henning’s comments about
 thermals are well-taken — even a simple folded up carboard shield helps.
 But I think you’re near the limit.
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] HP-3458A Zero Reading

[Randy Evans]

A bit of a false lead.  I took the readings after an hour of warmup.
However, after about two hours, the zero reading went to less thatn 0.2 uV,
which seems just fine to me.  I guess i just needed to get a really good
warmup time.

However, the 752 readings are varying over several uV when doing the CAL
procedure.  I am currently using unshielded leads so I suspect I am getting
a lot of noise.  Time to invest in some really good cables I guess.  I was
hoping to build my own cables as Bill Gold had suggested in a previous
thread.

Randy AE6YG
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] HP-3458A Zero Reading

[Randy Evans]

I shorted the input terminals of my HP-3458A with a short lead of copper
wire, Bell telephone wire as recommended in the manual.  The reading I get
is around 000.00070 mV, or 0.7 uV with NLPC set to 100.  I was trying to
evaluate it's use as a null meter for my Fluke 752A divider.  This seems a
little higher than I would expect but no amount of running AUTOCAL or ZERO
changes this amount.  Is this considered acceptable?

Randy AE6YG
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Test Leads

[Randy Evans]

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
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Oven thermal insulation

[Randy Evans]

Frank,

I don't plan on operating at 80C. I just want an insulation that can
withstand up to 80C so i have a safety margin.  45C is probably too low for
my environment but 50C might be doable.

Thanks,

Randy

On Tue, Jul 7, 2015 at 12:29 AM, Frank Stellmach frank.stellm...@freenet.de
 wrote:


 Hi Randy,


 80°C and 'highest stability' is simply a contradiction in itself.
 Therefore, if you really go for highest stability, please run your voltage
 reference at  60°C only, best would be 45°C!

 In this case, ordinary styrofoam is suitable, higher temperatures require
 poly sulfone, like used on the HP3458A reference board, or the VALOX(TM)
 plastic which is used for the LM399.

 Frank



 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Oven thermal insulation

[Randy Evans]

I am working on a voltage reference deisgn that will go into an oven for
the highest stability.  I am looking for a good insulation material that
can stand high temperatures safely (up to 80C).  Looking at some HP
frequency standard ovens I see a hard, light-weight insulation material of
some type that looks like it would work really well, but I have no idea
what it is.  Does anyone have any suggestions?

Thanks,

Randy Evans AE6YG
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-419A Fluke 845A Mods - shared link

[Randy Evans]

Dave,

I should have checked it.  I will generate a higher resolution version
tomorrow.

Randy

On Wed, Jun 24, 2015 at 10:49 AM, Dave M dgmin...@mediacombb.net wrote:

 Rady,
 Many thanks for the uploads.
 One issue... the marked-up PDF of the HP 419A schematic is virtually
 unreadable.  Could you post a higher resolution image of the markup
 details? Don't really need the full schematic, just the areas where the
 connections to the new circuit are made.


 Thanks again,
 Dave M


 Randy Evans wrote:

 I have created a shared link to my working folder with the details of
 the HP-419A and Fluke 845A modifications.  It is an in-process design
 so I suspect there may be many questions.  Just send your questions
 and I will try to answer them.  In the meantime, I will try to find
 time to clean up the design a bit.

 Hopefully I created the link correctly.  Let me know if you have any
 issues with the link.

 https://www.dropbox.com/sh/7b3hsy0j0wq35hw/AABkmVptTwVu2EJFRqtSdAjya?dl=0


 Randy Evans AE6YG



 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] HP-419A Fluke 845A Mods - shared link

[Randy Evans]

I have created a shared link to my working folder with the details of the
HP-419A and Fluke 845A modifications.  It is an in-process design so I
suspect there may be many questions.  Just send your questions and I will
try to answer them.  In the meantime, I will try to find time to clean up
the design a bit.

Hopefully I created the link correctly.  Let me know if you have any issues
with the link.

https://www.dropbox.com/sh/7b3hsy0j0wq35hw/AABkmVptTwVu2EJFRqtSdAjya?dl=0


Randy Evans AE6YG
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-3458A questions

[Randy Evans]

Frank,

Thanks for the data.  The 100K seems acceptable since I have a Fluke 732A
 to recalibrate the 3458A with after the change and the 3458A is not in a
rack.

Randy

On Tue, Jun 2, 2015 at 2:50 PM, Frank Stellmach frank.stellm...@freenet.de
wrote:

 Hi Randy,

 in advance, this change only improves the stability of the instrument,
 when the 3458A is powered.
 The LTZ1000 will not age (nearly), when the instrument is switched off.
 Therefore, it makes sense mainly, if your instrument is running for an
 extended period of time.

 (Reference: Spreadbury: Ultra Zener..)

 If you change the oven temperature, you will loose the 10V calibration, as
 the LTZ1000A will change its reference voltage.


 Although my instrument is strictly switched off, when not doing
 measurements, I reduced the oven temp. by connecting a 100k precision
 wirewound (3ppm/K) in parallel to the 15k BMF resistor. That gives 13k in
 total, yielding about 65°C like in the LT datasheet.
 An alternative placement is already foreseen on the PCB; in the CLIP, it's
 component designator is X411.
 I'll try to link in a photo of my change.

 lymex on the bbs35.hot forum obviously was more agressive, and paralled
 75k of Vitrohm Thin Film, giving 12.5k for about 55°C.

 I would recommend my solution above the one of lymex, although his one
 gives theoretically more stability.
 Also, the lower stability of TF reistors may affect the stability (T, t)
 of the 15k BMF.

 With 100k/65°C, the oven runs about 30°C lower.
 Therefore, the ambient temperature has to be limited to max. 35°C, the fan
 has ALWAYS to be kept clean, giving a maximum temperature rise of 15°C, and
 the instrument may not be put in a rack (which would give additional
 10..20°C temperature rise). Under these conditions, (35°C ambient + 15°C
 3458A inner heating + 10°C self heating of LTZ1000A + 5°C regulation
 margin), the oven will always be stable.

 These 75k / 55°C would be possible, only if you limit the ambient
 temperature further, to = 25°C, and precisely monitor the 3458A inner
 temperature (TEMP?).

 Although my instrument is kept at 20..23°C throughout the year, i wouldn't
 feel comfortable with 55°C.
 The only possibility would be the exchange of the reference to the non-A
 version, as the self heating effect may vanish!

 Frank

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] HP-3458A questions

[Randy Evans]

Does anyone have explicit instructions on how to lower the temperature of
the LTZ1000 for better stability; e.g., what resistors to change and to
what value?

Similarly, step-by-step instructions on how to back up the cal ram in the
HP-3458A?  I now Mark Sims posted his program on Jon Miles site but I am
confused how to use it (I want to back up my HP-3458A before I attempt to
replace the display board).

thanks,

Randy Evans AE6YG
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-3458a display board

[Randy Evans]

Tom,

I was told by Tech Support that the replacement display board is
refurbished but the display is new.

Randy

On Wed, Apr 15, 2015 at 8:08 PM, Tom Knox act...@hotmail.com wrote:

 Hi Randy;
 I saw the same thing, That is a great deal, I though they were much more
 expensive. Even at half the price I would use the Keysight exchange program
 since they recently started offering free courier pick up, In addition you
 would have a warranty and most likely have a new VFD.
 Cheers;
 Thomas Knox

 Ascent Concepts and Technology

 4475 Whitney Place
 Boulder Colorado 80305

 1-303-554-0307

  Date: Wed, 15 Apr 2015 14:39:38 -0700
  From: randyevans2...@gmail.com
  To: volt-nuts@febo.com
  Subject: Re: [volt-nuts] HP-3458a display board
 
  FYI,
 
  I contacted Keysight and found the exchange program is still in place.
 The
  PN is 03458-69517 and the price is $278.
 
  Randy Evans AE6YG
 
  On Wed, Apr 15, 2015 at 12:05 PM, Randy Evans randyevans2...@gmail.com
  wrote:
 
   I need to replace the display board for my HP-3458A (several dim to
   missing pixels).  There used to be a swap program for the display
 board but
   I can't find it on Keysight's website.  Does anyone know if it's still
   available?  If so, how do I find it?
  
   Thanks,
  
   Randy Evans
  
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-3458a display board

[Randy Evans]

FYI,

I contacted Keysight and found the exchange program is still in place.  The
PN is 03458-69517 and the price is $278.

Randy Evans AE6YG

On Wed, Apr 15, 2015 at 12:05 PM, Randy Evans randyevans2...@gmail.com
wrote:

 I need to replace the display board for my HP-3458A (several dim to
 missing pixels).  There used to be a swap program for the display board but
 I can't find it on Keysight's website.  Does anyone know if it's still
 available?  If so, how do I find it?

 Thanks,

 Randy Evans

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Link to LTZ1000 temperature calculation plot

[Randy Evans]

Thanks Jan,

These plots should prove very useful.

Randy Evans

On Sun, Feb 15, 2015 at 4:12 AM, Jan Fredriksson j...@41hz.com wrote:

 It's reply #984 in the thread. See also #982

 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/msg605967/#msg605967

 Direct to plot file of reply #984

 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/?action=dlattach;attach=135476

 Direct to plot file of reply #982

 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/?action=dlattach;attach=135338

 Jan

 
  Would you please post the link to your plot?  I searched but haven't
 found
  it yet.
 
  thanks,
 
  Randy Evans
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] LTZ1000A Heater Temp (Ben Clark)

[Randy Evans]

Jan,

Would you please post the link to your plot?  I searched but haven't found
it yet.

thanks,

Randy Evans

On Thu, Feb 12, 2015 at 3:51 AM, Jan Fredriksson j...@41hz.com wrote:

 I posted a plot of calculated resistor values versus temperature in
 the LTZ1000 thread on the EVV blog yetserday. Email me if you can't
 find it.

 I guess the 3458A was specified to be used at north pole and desert
 heat, that's why they have such a high temperature setting. They could
 have a laboratory version and a field version of the reference

 I have a NI-4071 PXI DMM with a LTZ1000 and it uses 14.3 ratio to
 fulfill the PXI specified temperature range. Still higher than optimal
 for stability but the temperature in my PXI rack is typically 40C at
 20C room temperature.

 my2C
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay

[Randy Evans]

The reference module is in a metal box and uses an external linear PS with
internal separate regulation.  I don't think its external EMI, but anything
is possible.

Randy

On Wed, Jan 28, 2015 at 10:28 PM, Hendrik Dietrich don_he...@gmx.de wrote:


 Am 29.01.2015 04:07, schrieb Randy Evans:

 I bought two HP-3458A ref boards from John Daly (he no longer has any
 more)
 and they worked fine but have intermittent noise bursts.  I suspect they
 were rejects from HP/Agilent.  At some point I will probably replace the
 LTZ1000As and reduce the internal temperature set point for better
 stability.  Has anyone else had any issues with these units?

 BTW, I packaged the units in an enclosure for a stand-alone reference and,
 except for the occasional noise bursts, seem very stable according to my
 HP
 3458A and fluke 732A/ESI RV722 KVD.

 Randy


 Hi Randy,

 Noise bursts, especially if they get back on track again, sound like
 electromagnetic interference from your short description.
 If applicable, turn of the CFL or LED lighting, replace the switch-mode
 power supply with a linear one or even better a battery,, try a known
 non-reject in place of the ebay reference module, spread some capacitors
 on/around the module and/or invest in a metal box.

 Hendrik




 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay

[Randy Evans]

I bought two HP-3458A ref boards from John Daly (he no longer has any more)
and they worked fine but have intermittent noise bursts.  I suspect they
were rejects from HP/Agilent.  At some point I will probably replace the
LTZ1000As and reduce the internal temperature set point for better
stability.  Has anyone else had any issues with these units?

BTW, I packaged the units in an enclosure for a stand-alone reference and,
except for the occasional noise bursts, seem very stable according to my HP
3458A and fluke 732A/ESI RV722 KVD.

Randy

On Wed, Jan 28, 2015 at 9:40 AM, John Phillips john.philli...@gmail.com
wrote:

 There is a bottom cover under the board.

 On Tue, Jan 27, 2015 at 9:01 PM, J. L. Trantham jlt...@att.net wrote:

  When these boards are installed in a 3458A, the LTZ1000 is covered by a
  small, white, 'hat' that mounts with screws that pass through the two
 holes
  on opposite sides of the LTZ1000.  I've never removed the board to see if
  there is anything on the bottom of the board that would cover the bottom
 of
  the LTZ1000.
 
  Does anyone know what this 'hat' is constructed of or the
  HP/Agilent/Keysight part number of this item is?  Is it available from
  Keysight?
 
  In the 3458A the reference board is under a cover that covers about half
  of the top of the meter but not 'insulated' beyond that, except for the
  'hat' referred to above.
 
  It would appear desirable to find what that 'hat' is and see if something
  could be fabricated to 'insulate' the LTZ1000 for a 'do it yourself'
  standalone reference.
 
  Would appreciate hearing anything about how the reference board is
  'insulated' in the 3458A.
 
  Thanks.
 
  Joe
 
 
  -Original Message-
  From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Orin
 Eman
  Sent: Tuesday, January 27, 2015 11:45 AM
  To: Discussion of precise voltage measurement
  Subject: [Bulk] Re: [volt-nuts] 3458A reference boards on ebay
 
  Dave,
 
  I'll be putting it in an enclosure to use as a reference.  It will
  probably be a smallish diecast aluminium box.  It's what I did with my
  Geller SVR-T and it compared very well with my Fluke 731B.  I'll likely
 use
  Pomona 3770 binding posts for output (I used them to repair the 731B).
  I'll also use the protection circuits from the Fluke 732 on the output -
  big reverse diode, gas discharge tube and TVS as I recall (I plan to add
  these protection circuits to the 731B).
 
  I'll likely do a PCB for it, though the local equivalent of veroboard
  would likely be OK; the socket spacing is 0.9 and the pin spacing 0.1.
  My meters are also 6 1/2 digit (3456A and 34461A) so I'm not too
 concerned
  with thermal EMFs with one count being 10uV on the 10V range.  However, I
  will try to avoid temperature gradients and keep the outputs close
  together.  I'll use star wiring for the 18V and ground as in the
 following:
 
  http://www.maxmcarter.com/vref/
 
  It is debatable whether the -15V supply is needed - I'll test with and
  without.  I'd add a few tantalum capacitors to the above design - on the
  regulator outputs and on the 3320 resistor, along with protection diodes
  for the LM317.
 
  There is also a HUGE thread about the LTZ1000 on EEVBlog - I'll be
  reviewing that for ideas:
 
  http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/
 
  I actually have a couple of LTZ1000As here that I was going to DIY, but
  never got around to getting the precision resisters .  I think there is a
  source in England mentioned in the EEVBlog thread.
 
  Orin.
 
  On Tue, Jan 27, 2015 at 2:24 AM, Dr. David Kirkby (Kirkby Microwave Ltd)
 
  drkir...@kirkbymicrowave.co.uk wrote:
 
   On 27 January 2015 at 09:16, Orin Eman orin.e...@gmail.com wrote:
There is a seller letting a slow trickle of them out there... they
seem
   to
be going for about $165.  The current batch of two is around $100,
but
   will
probably be bid up.
   
I just received one that I won.  Seems to be working fine after a
quick breadboard lashup.  I'll be making an enclosure for it next.
   
A little expensive IMO, but given the trouble getting the precision
resistors to DIY with the LTZ1000A, probably worth it.
   
Orin
  
   Orin,
  
   What do you intend doing with it?
  
   I was thinking about getting one of those, with a view to putting it
   in a box with a couple of terminals to have something to compare with
   my 6.5 digit 3457A.  But what put me off is a lack of knowledge in
   knowing how to convert a 3458A reference board into a boxed unit with
   a known output voltage at the terminals. How would I avoid / control
   thermal EMFs?
  
   I'd be interested to hear what your plans are for it, and how you
   intend tackling those issues.
  
   Do you know what the difference in the reference is between a standard
   3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm
   guessing the chips for the option 002 might be the top performing
  

[volt-nuts] Design Spark PCB Design Package

[Randy Evans]

This is indirectly pertinent to the group since I am designing a PCB for
the HP-419A and Fluke 845A modifications.  Does anyone have any
experience/comments on the Design Spark PCB design package?  Is is a viable
package for hobbyist use?

thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[Randy Evans]

Stan,

I working for a daughterboard design.  I will be using parts of the
existing circuitry and I am not worried about maintaining purity.  I just
want a functioning nullmeter.

Randy

On Tue, Dec 9, 2014 at 9:25 PM, Stan Katz stan.katz...@gmail.com wrote:

 Hi Randy,

 I have a very pedestrian and naive question regarding the fab of the
 chopper eliminator board for the HP419A. Is it your intention to replace
 the A4 board with a board containing your new design? If so, you have to
 keep in mind the A4 board is a whopping .173 thick.  Expresspcb seems to
 only have one thickness in their fab of .062. I'm sure that wont mate well
 with the existing connector. There are other fab houses that can provide
 boards as thick as .125 stateside (sunstone.com), or pcbcart.com China
 (.126). Even using these other fabs leaves almost 50 mil short of the
 original A4 thickness. Maybe the connector can make up the 50 mil
 shortfall? If this is just a 2-sided board, you could split the layers onto
 two circuit boards with thicknesses that come close to the original A4
 board. These boards would have to be epoxied together by the end user.
 In any event, you may not get by using Expresspcb since two of their boards
 combined still leaves that 50 mil shortfall.

 All of the above is easily dismissed if you intend to mount a daughterboard
 onto the A4, cut the traces on the A4 down near the connector, and then
 wiring the daughter board onto the trace remnants still running to the
 connector. The only downside would be no resale to a purist who wants to
 run with the David Wise HP H11 linear optocoupler/photochopper replacement
 (see HP yahoo group for HP740b ).

 Just curious,
 Stan

 On Wed, Nov 26, 2014 at 12:18 PM, Randy Evans randyevans2...@gmail.com
 wrote:

  I have finished the design and analysis (LTSpice) and I am preparing the
  BOM and doing a PCB layout now (ExpressPCB).  I am hoping to finish the
  work over the Thanksgiving holidays but I wanted to see Dallas's 845A
  modifications before ordering parts and pulling the plug on PCB fab first
  but it hasn't shown up on K04BB's site yet (still in the upload section).
 
  Randy
 
  On Wed, Nov 26, 2014 at 4:06 AM, ludger.len...@gmx.de wrote:
 
   Hi Randy,
  
   did you finish the HP-419A modification with a modern chopper amp?
  
   I have to refurbish my HP-419A so it would make sense to replace the
   optical chopper. Any help or made expericance would perfect.
  
   BR
   Ludger / PeLuLe
  
   *Gesendet:* Samstag, 09. August 2014 um 03:23 Uhr
   *Von:* Randy Evans randyevans2...@gmail.com
   *An:* Discussion of precise voltage measurement volt-nuts@febo.com
   *Betreff:* Re: [volt-nuts] HP-419 and Fluke 845 Modifications
   For those interested, I have largely finished the design of the HP-419A
   modifications to replace the current active circuits with a more modern
   chopper amp; e.g., LTC2054. The LTSpice analysis shows the circuit
 draws
   0.3 mA at full scale meter readings using a single 6V battery. I think
 I
   will use a 6V 225mAH NiCad rechargeable battery (because I have some)
  that
   should last many many hours on one charge. I am still working out the
   board layout and unit mods but the circuit is extremely simple and will
  use
   all the existing range and mode switching circuits. The circuit should
   also work for the Fluke 845 also. Keep tuned.
  
   Randy
  
  
   On Mon, Aug 4, 2014 at 10:05 AM, Dave M dgmin...@mediacombb.net
 wrote:
  
From: Randy Evans randyevans2...@gmail.com
   
   
I am looking at modifying my (defective) HP419A and Fluke 845A Null
meters
using the LTC2054 zero drift op amp. I am planning on using a single
4.2 V
Lithium Ion battery to power them (no AC input required and may not
include, TBD). The LTC2054 has a very low bias current of typically
1pA at
room temp and the bias plots vs. temp show no appreciable increase
until
about 50C. Conceptually, it looks pretty straight forward and, based
on my
Fluke 887A modifications, likely will be very stable.
   
Since this is a very astute group, does anyone have any comments on
the
feasibility of this modification before I get too involved?
   
Regards,
   
Randy Evans
   
   
   
Hi Randy. Good to hear from you again.
I have modified two 883A models and one 887A model DMMs using your
details, with great results. I have a model 845A null meter that is
working fine right now, but who knows how long that will last. I
 would
surely welcome some research on modifying it with a zero-drift opamp.
  One
concern that I would have with that mod would be that some mechanism
   would
need to be added to retain the isolation of the recorder output and
  guard
integrity that's afforded by the photo-modulator/demodulator circuit.
Perhaps some kind of optically-isolated interface might be in order
   
Some Spice runs on the original circuit would be interesting to see

Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[Randy Evans]

The Fluke 845A is a very easy modification (in theory) since all that is
needed is a zero drift amp with a follow-up amp (need more gain to close
the loop with at least 40 dB margin).  The LTC2054 and LTC6255 with two
voltage regulators to drop the +/-15V to +/- 2.5V for the op amps should be
all that is needed.  Might want two 1.25V regulators for the zero offset to
minimize drift similar to what Dalla Smith did in his mod.  I wanted to use
the LTC2054 since it has 1 pA bias current around room temp.  Probably need
a PCB since IC sockets are a no-no to minimize thermals.  The PCB would be
very simple but expensive since the cost at ExpressPCB is $66 for three
(with tax and shipping) the last time I ordered.  I could probably fit at
least 6 circuits total on the three PCBs if anyone else is interested in
buying some of the PCBs for their mods.

Randy

On Tue, Dec 2, 2014 at 10:45 AM, Dallas Smith dosm...@outlook.com wrote:

 Randy,

 I'm glad to see that you completed your design, This could be the ultimate
 permanent solution for these meters. My LED mod is still working very well,
 but I think the zero of your design will solve the offset drift
 problem. My led mod has a drift about ±100nv's over a day or so, not
 perfect but better than the original specs. I changed the value of C116 to
 22uf tantalum, the response was a little to slow for overloads. Your design
 may eliminate the need for the zero control entirely.

 Do the light pipes contribute to the high isolation resistance that the
 Fluke 845 has? Will your modifications improve this spec? I may consider
 your mod as a improved version, after your testing.

 Since the mod, I was able to complete the self calibration of my Fluke 720
 from beginning to end without the need to re-adjust the null meters zero.
 This was the driving source for my mod,

 Dallas


  Randy Evans wrote:

 I finished the H-419A/Fluke 845A design modifications but I am still
 trying to decide on the preferred power supply design.  The basic
 meter circuit uses the LTC2054 and LTC6255 with two CR123 Li-Ion 3 V
 batteries.  The
 basic meter circuit draws less than 0.2 mA and with 1500 mAH CR123A
 batteries should be able to go several thousand hours on a set of
 batteries.   For the meter circuit, it is always battery powered and
 doesn't have to be plugged into the mains.

 I also added a TI  AMC1100 isolation amplifier for recording output
 but it needs a 3.3 VDC isolated supply and a 5VDC output supply.  The
 current design  uses separate isolation power supplies using  LT8300
 ICs that work off the mains transformer so there would be no worry
 about failing batteries.  Therefore, to use the recorder, the unit
 would have to be plugged in. I am trying to decide if it would be
 simpler to use batteries for the isolation circuit as well. If I use
 batteries, do I use rechargeables or non-rechargeable batteries such
 as the CR123s?  The
 circuit would need one set for the input isolated circuit side and
 another set for the recorder output side and the batteries would not
 last as long
 as the meter circuit since the isolation circuits draw about 12
 milliamps. They would still work about one hundred hours most likely
 and would not
 draw any current unless the isolation circuit is turned on (with a
 separate toggle switch).  My preference is to stay with the LT8300
 power supplies
 but I thought I would query the group.

 Any thoughts on what would be your preferences?

 Thanks,


 __
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.



 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[Randy Evans]

Dave,

The HP-419A is driving the need for an isolated recording output (it
doesn't have one in the basic unit) and I wanted to provide one.The
circuit is being designed to work with either the HP-419A or the Fluke
845A.  The isolation circuit does not have to be used if not wanted since
it is a completely separate circuit and not needed for the meter to work.
I still need to work on the final HP-845A modifications and i will look at
your suggestions.

Randy

On Sun, Nov 30, 2014 at 6:37 PM, Dave M dgmin...@mediacombb.net wrote:

 Randy,
 Thanks for continuing with this modification.

 Speaking of the Fluke 845A;
 At first glance, you could probably leave the existing power supply
 inverter circuit intact, as well as the isolation transformer for the
 recorder output, with the recorder output transformer being driven (at the
 center tap) by the output of the last DC amp stage of the null amp
 circuit.  That would maintain the isolation of the meter and recorder
 output, and eliminate the need for an extra amp for them.  It would also
 maintain the guard integrity, keeping the instrument's operational
 characteristics as close to original as possible.
 By leaving the existing inverter circuit in place, you can easily derive
 any voltages (+ and -) that your mod needs from it, without the need for
 additional isolated power supplies

 Dave M



 Randy Evans wrote:

 I finished the H-419A/Fluke 845A design modifications but I am still
 trying to decide on the preferred power supply design.  The basic
 meter circuit uses the LTC2054 and LTC6255 with two CR123 Li-Ion 3 V
 batteries.  The
 basic meter circuit draws less than 0.2 mA and with 1500 mAH CR123A
 batteries should be able to go several thousand hours on a set of
 batteries.   For the meter circuit, it is always battery powered and
 doesn't have to be plugged into the mains.

 I also added a TI  AMC1100 isolation amplifier for recording output
 but it needs a 3.3 VDC isolated supply and a 5VDC output supply.  The
 current design  uses separate isolation power supplies using  LT8300
 ICs that work off the mains transformer so there would be no worry
 about failing batteries.  Therefore, to use the recorder, the unit
 would have to be plugged in. I am trying to decide if it would be
 simpler to use batteries for the isolation circuit as well. If I use
 batteries, do I use rechargeables or non-rechargeable batteries such
 as the CR123s?  The
 circuit would need one set for the input isolated circuit side and
 another set for the recorder output side and the batteries would not
 last as long
 as the meter circuit since the isolation circuits draw about 12
 milliamps. They would still work about one hundred hours most likely
 and would not
 draw any current unless the isolation circuit is turned on (with a
 separate toggle switch).  My preference is to stay with the LT8300
 power supplies
 but I thought I would query the group.

 Any thoughts on what would be your preferences?

 Thanks,

 Randy Evans

 On Mon, Aug 4, 2014 at 8:33 AM, Randy Evans randyevans2...@gmail.com
 wrote:

  I am looking at modifying my (defective) HP419A and Fluke 845A Null
 meters using the LTC2054 zero drift op amp.  I am planning on using
 a single 4.2 V Lithium Ion battery to power them (no AC input
 required and may not include, TBD).  The LTC2054 has a very low bias
 current of typically 1pA at room temp and the bias plots vs. temp
 show no appreciable increase until about 50C.  Conceptually, it
 looks pretty straight forward and, based on my Fluke 887A
 modifications, likely will be very stable.

 Since this is a very astute group, does anyone have any comments on
 the feasibility of this modification before I get too involved?

 Regards,

 Randy Evans



 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[Randy Evans]

I have finished the design and analysis (LTSpice) and I am preparing the
BOM and doing a PCB layout now (ExpressPCB).  I am hoping to finish the
work over the Thanksgiving holidays but I wanted to see Dallas's 845A
modifications before ordering parts and pulling the plug on PCB fab first
but it hasn't shown up on K04BB's site yet (still in the upload section).

Randy

On Wed, Nov 26, 2014 at 4:06 AM, ludger.len...@gmx.de wrote:

 Hi Randy,

 did you finish the HP-419A modification with a modern chopper amp?

 I have to refurbish my HP-419A so it would make sense to replace the
 optical chopper. Any help or made expericance would perfect.

 BR
 Ludger / PeLuLe

 *Gesendet:* Samstag, 09. August 2014 um 03:23 Uhr
 *Von:* Randy Evans randyevans2...@gmail.com
 *An:* Discussion of precise voltage measurement volt-nuts@febo.com
 *Betreff:* Re: [volt-nuts] HP-419 and Fluke 845 Modifications
 For those interested, I have largely finished the design of the HP-419A
 modifications to replace the current active circuits with a more modern
 chopper amp; e.g., LTC2054. The LTSpice analysis shows the circuit draws
 0.3 mA at full scale meter readings using a single 6V battery. I think I
 will use a 6V 225mAH NiCad rechargeable battery (because I have some) that
 should last many many hours on one charge. I am still working out the
 board layout and unit mods but the circuit is extremely simple and will use
 all the existing range and mode switching circuits. The circuit should
 also work for the Fluke 845 also. Keep tuned.

 Randy


 On Mon, Aug 4, 2014 at 10:05 AM, Dave M dgmin...@mediacombb.net wrote:

  From: Randy Evans randyevans2...@gmail.com
 
 
  I am looking at modifying my (defective) HP419A and Fluke 845A Null
  meters
  using the LTC2054 zero drift op amp. I am planning on using a single
  4.2 V
  Lithium Ion battery to power them (no AC input required and may not
  include, TBD). The LTC2054 has a very low bias current of typically
  1pA at
  room temp and the bias plots vs. temp show no appreciable increase
  until
  about 50C. Conceptually, it looks pretty straight forward and, based
  on my
  Fluke 887A modifications, likely will be very stable.
 
  Since this is a very astute group, does anyone have any comments on
  the
  feasibility of this modification before I get too involved?
 
  Regards,
 
  Randy Evans
 
 
 
  Hi Randy. Good to hear from you again.
  I have modified two 883A models and one 887A model DMMs using your
  details, with great results. I have a model 845A null meter that is
  working fine right now, but who knows how long that will last. I would
  surely welcome some research on modifying it with a zero-drift opamp. One
  concern that I would have with that mod would be that some mechanism
 would
  need to be added to retain the isolation of the recorder output and guard
  integrity that's afforded by the photo-modulator/demodulator circuit.
  Perhaps some kind of optically-isolated interface might be in order
 
  Some Spice runs on the original circuit would be interesting to see.
 
  Dave M
 
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to https://www.febo.com/cgi-bin/
  mailman/listinfo/volt-nuts
  and follow the instructions there.
 
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] 732A rear panel battery connector

[Randy Evans]

Charles,

Thanks for the update.  I was able to get a cable plug set from Todd
Micallef.

Randy

On Mon, Oct 20, 2014 at 6:23 AM, Charles Steinmetz csteinm...@yandex.com
wrote:

 Randy wrote:

  Does anyone have a spare connector plug for the 732A external battery
 *** ( I saw several in discussions but I'm not sure which is the best part
 number to use).


 Back in March, I reported on my friend's adventure to get the contact
 bodies and contacts from Fluke.  The problem was, the designers of the 732A
 used male pin contacts in the panel receptacles and female socket contacts
 in the cable plugs -- backwards from the way they are used by every other
 user of those connectors (including the present Fluke users -- they are
 used in certain medical equipment).  Fluke understood the problem and told
 him they planned to create a new part number with the right components for
 the 732A, and would let him know what it was.

 Having heard nothing since then, I asked my friend if he had heard back
 from Fluke.  He had not, so he called his Fluke contacts and was told that
 Fluke had decided not to catalog the plugs for the 732A.  So, Kensington
 Electronics is probably the best source.

 Best regards,

 Charles




 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] 732A rear panel battery connector

[Randy Evans]

Does anyone have a spare connector plug for the 732A external battery
connector that they would be willing to sell.  Or conversely, a good Fluke
PN for the connector ( I saw several in discussions but I'm not sure which
is the best part number to use).

Thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Old HP3458A - SN: 2823A 03939

[Randy Evans]

I checked my 3458A and it says that the Rev is 8.2.  What can I infer about
the unit?  I have not opened it up yet to check the status of  the NVRAM
since I am waiting for the posidrive tools.

Randy

On Sun, Sep 21, 2014 at 9:20 AM, J. L. Trantham jlt...@att.net wrote:

 Not in front of my meter right now but IIRC, 'Blue Key' (shift), 'R',
 'Down Arrow' until you find Rev? then hit enter.  It will return something
 like 7,1 or 8,2 etc.

 The first digit is the master processor firmware version and the second
 number is the slave processor firmware version.  The master processor
 firmware is located on the A5 Board, the Outguard Controller.  I'm not sure
 where the slave processor firmware is located.  9,2 is the latest AFAIK.
 I've heard that there is not much difference between 8 and 9.

 I don't know how to check for the Service Note Compliance.  Would probably
 have to read each note then explore the meter to see what is installed.

 Good luck.

 Joe

 -Original Message-
 From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of cfo
 Sent: Sunday, September 21, 2014 10:22 AM
 To: volt-nuts@febo.com
 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

 ___
 volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] 732A and 3458A stability

[Randy Evans]

I ran a stability test on my  new 732A and 3458A units.  I had both
connected together (using copper wire leads) and I randomly ran
measurements of the 3458A reading of the 732A 10 VDC output.  I did an ACAL
DCV before each reading and used NPLC of 100 and 8 digit readings , and
recorded the room temp, 3458A internal temp , and the MIN/MAX/MEAN/STDDEV
of the 3458A readings, and the thermistor value of the 732A.

The room temp varied from 22.1 to 27.9 C over the several days of
 measurements.  The 3458A internal temp was, on average, 13.7 C higher than
the room temp.  The end result was a temperature sensitivity of 1.15uV per
degree C of the 3458A internal temp, or .115ppm/C.  I am assuming the 732A
is relatively stable over the changing temperature range (the thermistor
varied from 3666.6 to 3670.7 ohms) and attribute most of the variance to
the 3458A.

The absolute value of the readings are around 10.58 VDC but neither
unit is calibrated.  I assume they can be calibrated but I wanted to make
sure they are stable first.

Do these numbers look reasonable and do they indicate any issues with the
units?

Thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

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

[Randy Evans]

I am doing multiple 100 measurements simply to characterize the stability
of the 3458A and 732A units I just bought.  After about 10 measurement sets
over 2 days I am seeing a variance of about .5 uV for the 10V output, or
0.05 ppm.  However, the mean varies over a range of 10 uV, or 1 ppm.  Does
that sound reasonable/

Randy


On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote:

 hi randy,

 just for curiosity, why doing 100 measurements at nplc 1000. is this to
 sample a changing value?
 when i am doing 10 measurements from a stable signal at nplc 100 (only
 there many subsequent measuremnts with statistics make sense) I am already
 getting a stanard deviation below 0.1ppm.
 in a 30 minute test cycle, i would also be concerned about drifts (acal)
 unless the amb. temperature is really very stable (half a degree already
 adds about 0.25ppm at 10v)

 thanks




  Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr
  Von: Randy Evans randyevans2...@gmail.com
  An: Discussion of precise voltage measurement volt-nuts@febo.com
  Betreff: Re: [volt-nuts] 732A and Prologix received
 
  Is there any way to tell when the function key routine is complete?  In
 the
  case of taking multiple readings using the DEFKEY and MATH function, I
  don't see any indication when the routine is complete.  In one particular
  case, I am taking a 100 readings with NLPC set for 1000 so its a long
 while
  before it's complete, but i have to guess when it's done.
 
  Thanks,
 
  Randy
 
 
  On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans 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

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

[Randy Evans]

I forgot to mention that I reduced the number of measurements to 100 per
set since I wasn't seeing much difference in the variance between 100 and
1000 measurements and the 1000 measurement per set takes too long.

Randy


On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com
wrote:

 I am doing multiple 100 measurements simply to characterize the stability
 of the 3458A and 732A units I just bought.  After about 10 measurement sets
 over 2 days I am seeing a variance of about .5 uV for the 10V output, or
 0.05 ppm.  However, the mean varies over a range of 10 uV, or 1 ppm.  Does
 that sound reasonable/

 Randy


 On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote:

 hi randy,

 just for curiosity, why doing 100 measurements at nplc 1000. is this to
 sample a changing value?
 when i am doing 10 measurements from a stable signal at nplc 100 (only
 there many subsequent measuremnts with statistics make sense) I am already
 getting a stanard deviation below 0.1ppm.
 in a 30 minute test cycle, i would also be concerned about drifts (acal)
 unless the amb. temperature is really very stable (half a degree already
 adds about 0.25ppm at 10v)

 thanks




  Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr
  Von: Randy Evans randyevans2...@gmail.com
  An: Discussion of precise voltage measurement volt-nuts@febo.com
  Betreff: Re: [volt-nuts] 732A and Prologix received
 
  Is there any way to tell when the function key routine is complete?  In
 the
  case of taking multiple readings using the DEFKEY and MATH function, I
  don't see any indication when the routine is complete.  In one
 particular
  case, I am taking a 100 readings with NLPC set for 1000 so its a long
 while
  before it's complete, but i have to guess when it's done.
 
  Thanks,
 
  Randy
 
 
  On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans 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

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

[Randy Evans]

The HP3458A and the Fluke 732A are on continuously and I do an ACAL at
least every few hours, or when the room temperature changes by more than 1
degree C. The total range of measurements is 10uV so the drift is +/-5uV,
or 0.5 ppm.  The room temperature is not particularly stable and varies
over a 3C range.  The internal temp of the 3458 varies from 38.1 to 40.3
degrees C over the set of measurements.  The 732A thermistor resistance
measures from 3.6677 Kohms to  3.6686 Kohms.  I am using copper wires
between the 3458A and the 752A to minimize thermals.  At the moment I have
no way to tell which unit is drifting the most.

Randy


On Wed, Aug 27, 2014 at 6:41 AM, acb...@gmx.de wrote:

 well, what you do is to measure the stability of the 3458a. 1ppm drift
 though sounds much as overall short term average variation if your
 temperature is stable and your 3458a is always on. probably the temp is not
 stable, and that is what you see, amongst potentially some other smaller
 drifts like emf. before every cycle you should do an acal dcv, if you still
 see 10uv +/- drifts that then seems too much. (one thing I need to add is
 that one of my 3458a, not yet modified to have lower reference temperature,
 has drifts when switched on and off. that is not so much the case with
 modified reference. but my assumption re the above is that your meter is
 always on, as I said)
 732a references et al do have small short term drifts, you can determine
 them with a josephson element (these guys told me), but the 732a is
 certainly very stable short term compared to a 3458a. my 732a e.g. has a
 drift of 0.2ppm per year.


  Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr
  Von: Randy Evans randyevans2...@gmail.com
  An: Discussion of precise voltage measurement volt-nuts@febo.com
  Betreff: Re: [volt-nuts] 732A and Prologix received
 
  I forgot to mention that I reduced the number of measurements to 100 per
  set since I wasn't seeing much difference in the variance between 100 and
  1000 measurements and the 1000 measurement per set takes too long.
 
  Randy
 
 
  On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com
  wrote:
 
   I am doing multiple 100 measurements simply to characterize the
 stability
   of the 3458A and 732A units I just bought.  After about 10 measurement
 sets
   over 2 days I am seeing a variance of about .5 uV for the 10V output,
 or
   0.05 ppm.  However, the mean varies over a range of 10 uV, or 1 ppm.
 Does
   that sound reasonable/
  
   Randy
  
  
   On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote:
  
   hi randy,
  
   just for curiosity, why doing 100 measurements at nplc 1000. is this
 to
   sample a changing value?
   when i am doing 10 measurements from a stable signal at nplc 100 (only
   there many subsequent measuremnts with statistics make sense) I am
 already
   getting a stanard deviation below 0.1ppm.
   in a 30 minute test cycle, i would also be concerned about drifts
 (acal)
   unless the amb. temperature is really very stable (half a degree
 already
   adds about 0.25ppm at 10v)
  
   thanks
  
  
  
  
Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr
Von: Randy Evans randyevans2...@gmail.com
An: Discussion of precise voltage measurement volt-nuts@febo.com
 
Betreff: Re: [volt-nuts] 732A and Prologix received
   
Is there any way to tell when the function key routine is
 complete?  In
   the
case of taking multiple readings using the DEFKEY and MATH
 function, I
don't see any indication when the routine is complete.  In one
   particular
case, I am taking a 100 readings with NLPC set for 1000 so its a
 long
   while
before it's complete, but i have to guess when it's done.
   
Thanks,
   
Randy
   
   
On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans 
 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

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

[Randy Evans]

Don,

If I am reading your charts correctly, it looks like your system is cycling
over an 7 uV range over several days in summer, similar to what I am
seeing.  I don't have air conditioning (Northern California) so I do get
some pretty good temperature variations from day to night, but less inside
the house.

I need to figure out how to share files in Dropbox since I don't have my
own web site.  Good idea.

thanks,

Randy



On Wed, Aug 27, 2014 at 7:40 AM, Don@True-Cal truecalservi...@gmail.com
wrote:

 I have included a link to an ~30-hour measurement run that I consistently
 do that should give you some idea of expected measurement drift over time.
 Virtually all of the measurement drift is due to the 3458A internal
 temperature differences around the 7V reference caused by ambient
 temperature change. The drift associated with the 732A is probably about
 2-magnitudes less at this ambient temp drift. In my situation, the inferred
 ambient temperature is cycling with the home air-conditioning. Note the
 initial calibration temperatures as well as the ACal temperatures and where
 the 3458A is measuring exactly 10V relative to those temperatures. My
 primary 732A has been powered without loss for 4 years and 5 years before
 that. The 3458A is Agilent (Loveland) Cal'ed yearly and is powered 24-7-365
 except for the occasional mains power loss. The graphical measurements is
 using a homegrown Agilent VEE program. It is very helpful if not essential
 to get an HPIB interface setup so you can do long term graphical analysis.

 The other link was done in winter time when the lab a few degrees cooler.


 https://www.dropbox.com/s/8je482i3r0belqn/732A%20gold%20%26%203458A%20gold%2032-hour%20Ref%20Test%208-21-2014.pdf?dl=0


 https://www.dropbox.com/s/xv3l9py7tx6hyh7/HP%20732A%20gold%20%26%203458A%20gold%207-day%2010.0v%20Ref%20Test.pdf?dl=0

 I hope these Dropbox links work internationally - I'm new to using this
 sharing method.

 Don Johnson

 -Original Message-
 From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of
 acb...@gmx.de
 Sent: Wednesday, August 27, 2014 8:42 AM
 To: Discussion of precise voltage measurement
 Subject: Re: [volt-nuts] 732A and Prologix received

 well, what you do is to measure the stability of the 3458a. 1ppm drift
 though sounds much as overall short term average variation if your
 temperature is stable and your 3458a is always on. probably the temp is not
 stable, and that is what you see, amongst potentially some other smaller
 drifts like emf. before every cycle you should do an acal dcv, if you still
 see 10uv +/- drifts that then seems too much. (one thing I need to add is
 that one of my 3458a, not yet modified to have lower reference temperature,
 has drifts when switched on and off. that is not so much the case with
 modified reference. but my assumption re the above is that your meter is
 always on, as I said) 732a references et al do have small short term
 drifts, you can determine them with a josephson element (these guys told
 me), but the 732a is certainly very stable short term compared to a 3458a.
 my 732a e.g. has a drift of 0.2ppm per year.


  Gesendet: Mittwoch, 27. August 2014 um 14:36 Uhr
  Von: Randy Evans randyevans2...@gmail.com
  An: Discussion of precise voltage measurement volt-nuts@febo.com
  Betreff: Re: [volt-nuts] 732A and Prologix received
 
  I forgot to mention that I reduced the number of measurements to 100 per
  set since I wasn't seeing much difference in the variance between 100 and
  1000 measurements and the 1000 measurement per set takes too long.
 
  Randy
 
 
  On Wed, Aug 27, 2014 at 5:13 AM, Randy Evans randyevans2...@gmail.com
  wrote:
 
   I am doing multiple 100 measurements simply to characterize the
 stability
   of the 3458A and 732A units I just bought.  After about 10 measurement
 sets
   over 2 days I am seeing a variance of about .5 uV for the 10V output,
 or
   0.05 ppm.  However, the mean varies over a range of 10 uV, or 1 ppm.
 Does
   that sound reasonable/
  
   Randy
  
  
   On Tue, Aug 26, 2014 at 5:41 PM, acb...@gmx.de wrote:
  
   hi randy,
  
   just for curiosity, why doing 100 measurements at nplc 1000. is this
 to
   sample a changing value?
   when i am doing 10 measurements from a stable signal at nplc 100 (only
   there many subsequent measuremnts with statistics make sense) I am
 already
   getting a stanard deviation below 0.1ppm.
   in a 30 minute test cycle, i would also be concerned about drifts
 (acal)
   unless the amb. temperature is really very stable (half a degree
 already
   adds about 0.25ppm at 10v)
  
   thanks
  
  
  
  
Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr
Von: Randy Evans randyevans2...@gmail.com
An: Discussion of precise voltage measurement volt-nuts@febo.com
 
Betreff: Re: [volt-nuts] 732A and Prologix received
   
Is there any way to tell when the function key routine is
 complete?  In
   the
case of taking multiple readings using

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

[Randy Evans]

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 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

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

[Randy Evans]

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
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

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

[Randy Evans]

Bill,

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

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

Randy


On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold 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 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

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

[Randy Evans]

   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 out to the battery tabs
   regardless
 of the battery configuration if this is not done.

 You can find larger capacity batteries that will give you slightly
 more
 battery life. I lost a couple sets of mail-order batteries after a
 few
 extended outages. I would recommend going with locally bought
 batteries
 instead of the cheaper mail order. My local Batteries Plus will
   typically
 have some warranty if I remember correctly. Moving forward I will
 only
   use
 2 12v batteries and pre-charge them on a battery charger to
 equalize
   them
 before putting them in the 732A. I think the cheap batteries did
 not
 discharge equally, and would not recover when power was applied.

 Inspect the back plane for damaged traces and look at the
 capacitors. I
   had
 a few that looked questionable. So far, I have replaced all the big
   caps
   on
 the pre-regulator and regulator boards. My feeling is that once
 these
   go
 online, they should run as long as possible between repairs.

 The battery charger circuit may need adjusting. I tweaked mine and
 it
 seemed to work fine.

 Todd


 On Fri, Aug 22, 2014 at 10:42 PM, Randy Evans 
   randyevans2...@gmail.com
 wrote:

  I received my Fluke 732A today.  Just powered it up but it needs
 new
  batteries.  Any suggestions for sources (I haven't opened up the
 unit
 yet -
  I want to make sure it works before doing that).  Also received
 the
  ProLogix USB-GPIB adapter.  I plan on using Mark Sims' CAL ran
 data
 dumper
  program to get the CAL data from my 3458A.  Should be a busy
 weekend.
 
  Randy
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions

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

[Randy Evans]

Bill,

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


On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold 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 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

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

[Randy Evans]

Bill,

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

Randy



On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold 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 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

[volt-nuts] 732A and Prologix received

[Randy Evans]

I received my Fluke 732A today.  Just powered it up but it needs new
batteries.  Any suggestions for sources (I haven't opened up the unit yet -
I want to make sure it works before doing that).  Also received the
ProLogix USB-GPIB adapter.  I plan on using Mark Sims' CAL ran data dumper
program to get the CAL data from my 3458A.  Should be a busy weekend.

Randy
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] 732A drift

[Randy Evans]

I hope someone can help with a strange anomaly on either my 3458A or the
732A.  The 732A 10V output as measured on my 3458A seems relatively stable
over time (it bounces around about +/-1 uV but is it the 732 or the 3458?).
 However, the 1.000 VDC output drifts downward at a rate around 1-2 uV per
second as soon as I plug the 3458A into the 732 output. If I remove the
3458A and connect it back up after a few 10s of seconds, the reading goes
back to what it started at and then drifts downward again.  The 1.018V
output also drifts downward but at a much slower rate and not as much.  Now
the question is: is it the 732 or the 3458A?  I tried to see it on my
Agilent 34401A DMM but it really doesn't have the resolution, but I do seem
to see it on the 1.000VDC output.  If it is the 732A, what would cause it
to drift downward like that?  Since the 3458A has an input impedance of
10Gohm on the 1 and 10 V ranges, I wouldn't think the 732 would even see
the difference of whether the 3458A is connected of not, but it clearly
makes a difference as to how long its connected and how long it's been
disconnected.

Any one have any conjectures?

Also, what will turn on the In Cal light?  What does it mean if it
doesn't come on?

Thanks,

Randy
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

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

[Randy Evans]

Mark,

I just ordered the ProLogix USB-GPIB converter specifically to read the
contents of my 3458A.  Would it be possible to get a copy of your program
that you wrote to read the memory contents.  It would be greatly
appreciated and save me a lot of work and frustration.

thanks,

Randy


On Wed, Aug 20, 2014 at 5:33 PM, Mark Sims hol...@hotmail.com wrote:

 You REALLY don't want to mess with that 24 pin NVRAM chip... it contains
 the calibration memory.  If you bugger the data in it,  you get to spend a
 couple of grand getting the meter back into working order.  I know a couple
 of people that did just that.

 The solution is to first make a backup copy of the memory contents using
 the (undocumented) MREAD command over the GPIB bus.  Poul-Henning Kamp
 figured out how to do it... buy the man a beer... even better a case of
 beer...   Search the archives for details.

 I just backed up all the memory in my 3 HP3458A's for when the inevitable
 BIG BAD DAY comes and the backup batteries go bye-bye.   If you happen to
 have a NI GPIB-232CV-A (or possibly a Prologix) RS-232 to GPIB converter
 and can run a DOS or WIN98 program,  I have a program that dumps the memory
 chips.  It has code for the Prologix in it,  but I've only used it with my
 a Prologix compatible unit I built... I don't have a real Prologix to test
 it with.


 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] RE new 3458A

[Randy Evans]

Bill,

You are very helpful and I really appreciate it.

I entered BLUE-C-03458 and I still get the ERR message (106, OUT OF RANGE
-- CAL secured).  That would be consistent with what you are saying.  I
guess its no reason to panic yet.

I'm not sure how to use the SECURE command.   I guess it's time to open it
up but I will probably have to get some PosiDrive screwdrivers.

Thanks,

Randy


On Sun, Aug 17, 2014 at 11:39 AM, Bill Gold wpgold3...@att.net wrote:

 Randy:

 You are doing a ZERO calibration on the meter rather than a ACAL.  You
 have to give it a password after the 0 and then it will do the ZERO
 calibration.  Usually the password is 3458 and comes from the factory
 that
 way.  But someone could have changed it in the past.  You can do this from
 the front panel menu using the SECURE command.  But there is a jumper
 inside
 the 3458A which disables the request for a password so that you can do any
 CAL or reset the password to what you want.  So everything is working as
 expected.  The jumper is JM600 on the outguard processor board 66505 or
 66515 on the left of the meter inside.  Try 3458 first as most are set to
 this password.  Read the Calibration Manual pg. #8 for how to get inside of
 the meter.  You will need two sizes of a PosiDrive type screwdrivers to
 accomplish this.  Again in the Cal Manual.

 Bill

 - Original Message -
 From: Randy Evans randyevans2...@gmail.com
 To: Discussion of precise voltage measurement volt-nuts@febo.com
 Sent: Sunday, August 17, 2014 11:22 AM
 Subject: Re: [volt-nuts] RE new 3458A


  Bill,
 
  I installed the U-short and executed the BLUE-C-0 front panel command and
 I
  get an ERR on the display.  I assume this is not good.  Did I do this
  correctly?
 
  Thanks,
 
  Randy
 
 
  On Sun, Aug 17, 2014 at 10:49 AM, Bill Gold wpgold3...@att.net wrote:
 
   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

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

[Randy Evans]

Todd and Bill,

Thanks for the input.  The 3.6 K thermistor reading seems viable and i will
pursue it further.

I may have over committed myself to modifying the HP-419A, the Fluke 845A,
buying the 3458A and looking at buying a Fluke 732A.

So much to do and so little time.

Thanks again,

Randy


On Sun, Aug 17, 2014 at 11:48 AM, Bill Gold wpgold3...@att.net wrote:

 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
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] RE new 3458A

[Randy Evans]

That worked! Now it reads 000.00030mV.  So far it looks good except for the
display.

Thanks,

Randy


On Sun, Aug 17, 2014 at 12:54 PM, Bill Gold wpgold3...@att.net wrote:

 You need a comma , between the 0 and the 3458.  So blu CCAL
 0,3458 Enter.

 See pg. # 64 of the CAL Manual for the syntax.

 Bill

 - Original Message -
 From: Randy Evans randyevans2...@gmail.com
 To: Discussion of precise voltage measurement volt-nuts@febo.com
 Sent: Sunday, August 17, 2014 12:25 PM
 Subject: Re: [volt-nuts] RE new 3458A


  Bill,
 
  You are very helpful and I really appreciate it.
 
  I entered BLUE-C-03458 and I still get the ERR message (106, OUT OF
 RANGE
  -- CAL secured).  That would be consistent with what you are saying.  I
  guess its no reason to panic yet.
 
  I'm not sure how to use the SECURE command.   I guess it's time to open
 it
  up but I will probably have to get some PosiDrive screwdrivers.
 
  Thanks,
 
  Randy
 
 
  On Sun, Aug 17, 2014 at 11:39 AM, Bill Gold wpgold3...@att.net wrote:
 
   Randy:
  
   You are doing a ZERO calibration on the meter rather than a ACAL.
 You
   have to give it a password after the 0 and then it will do the ZERO
   calibration.  Usually the password is 3458 and comes from the factory
   that
   way.  But someone could have changed it in the past.  You can do this
 from
   the front panel menu using the SECURE command.  But there is a jumper
   inside
   the 3458A which disables the request for a password so that you can do
 any
   CAL or reset the password to what you want.  So everything is working
 as
   expected.  The jumper is JM600 on the outguard processor board 66505 or
   66515 on the left of the meter inside.  Try 3458 first as most are
 set
 to
   this password.  Read the Calibration Manual pg. #8 for how to get
 inside
 of
   the meter.  You will need two sizes of a PosiDrive type screwdrivers to
   accomplish this.  Again in the Cal Manual.
  
   Bill
  
   - Original Message -
   From: Randy Evans randyevans2...@gmail.com
   To: Discussion of precise voltage measurement volt-nuts@febo.com
   Sent: Sunday, August 17, 2014 11:22 AM
   Subject: Re: [volt-nuts] RE new 3458A
  
  
Bill,
   
I installed the U-short and executed the BLUE-C-0 front panel command
 and
   I
get an ERR on the display.  I assume this is not good.  Did I do this
correctly?
   
Thanks,
   
Randy
   
   
On Sun, Aug 17, 2014 at 10:49 AM, Bill Gold wpgold3...@att.net
 wrote:
   
 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

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

[Randy Evans]

I do have an ESI SR1 10Kohm standard, but I'm not sure its accurate
enough...time to look around I suppose.

BTW, I understand that TV twin lead, the copper wire type, makes a good
test lead for the 3458 measurements.  It seems reasonable, although the
leakage resistance might be questionable.

Randy


On Sun, Aug 17, 2014 at 1:36 PM, Todd Micallef tmical...@gmail.com wrote:

 Randy,

 Next thing you know, you will be looking at a 10K standard resistor to go
 with that 3458A and possible 732A.

 Todd


 On Sun, Aug 17, 2014 at 3:51 PM, Randy Evans randyevans2...@gmail.com
 wrote:

  Todd and Bill,
 
  Thanks for the input.  The 3.6 K thermistor reading seems viable and i
 will
  pursue it further.
 
  I may have over committed myself to modifying the HP-419A, the Fluke
 845A,
  buying the 3458A and looking at buying a Fluke 732A.
 
  So much to do and so little time.
 
  Thanks again,
 
  Randy
 
 
  On Sun, Aug 17, 2014 at 11:48 AM, Bill Gold wpgold3...@att.net wrote:
 
   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
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
   https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
  
   ___
   volt-nuts mailing list -- volt-nuts@febo.com
   To unsubscribe, go to
   https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
   and follow the instructions there.
  
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] New HP3458A

[Randy Evans]

I picked up a used HP3458A today, which I needed for some precision DC
measurements i need to make. It passes all the self tests and the Auto Cal
but is there any thing else I can check ( I have a 14 day RR).  It reads a
10V standard I made within a few tens of ppm, but it's not a 732A but that
is at least comforting.  It also reads an ESI 10Kohm standard resistor dead
on.

The only problem is that the display has some faint pixels in some
locations, with three in the second row for every digit location dead.
 Likely a pixel driver I would think.

 I am not too familiar with it yet but I noticed when I push the auto zero
button, the display has a blinking square until I hit a measurement mode
button; e.g., DCV, ACV, OHM, etc.  Is this normal?

Regards,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[Randy Evans]

Todd,

My 845 has the optical chopper circuit.  It quasi-works but the most
sensitive ranges are very noisy so I will replace the amplifier circuits
with a new chopper stabilized circuit after I finish the 419 modifications.

Randy


On Sat, Aug 9, 2014 at 7:48 AM, Todd Micallef tmical...@gmail.com wrote:

 Randy,

 I am looking forward to your test results. Does your 845 have the separate
 board for the chopper amp as mentioned in the change/errata sheet dated
 7/93? I have not seen any further documents from online sources that
 references this change. I have two AR models and it appears support for it
 was dropped long before 1993. It would be interesting to see how many of
 the original parts were removed and how this new board was mounted inside
 the AB chassis.


 Todd


 On Fri, Aug 8, 2014 at 10:23 PM, Randy Evans randyevans2...@gmail.com
 wrote:

  For those interested, I have largely finished the design of the HP-419A
  modifications to replace the current active circuits with a more modern
  chopper amp; e.g., LTC2054.  The LTSpice analysis shows the circuit draws
  0.3 mA at full scale meter readings using a single 6V battery.  I think I
  will use a 6V 225mAH NiCad rechargeable battery (because I have some)
 that
  should last many many hours on one charge.  I am still working out the
  board layout and unit mods but the circuit is extremely simple and will
 use
  all the existing range and mode switching circuits.  The circuit should
  also work for the Fluke 845 also.  Keep tuned.
 
  Randy
 
 
  On Mon, Aug 4, 2014 at 10:05 AM, Dave M dgmin...@mediacombb.net wrote:
 
   From: Randy Evans randyevans2...@gmail.com
  
  
   I am looking at modifying my (defective) HP419A and Fluke 845A Null
   meters
   using the LTC2054 zero drift op amp.  I am planning on using a single
   4.2 V
   Lithium Ion battery to power them (no AC input required and may not
   include, TBD).  The LTC2054 has a very low bias current of typically
   1pA at
   room temp and the bias plots vs. temp  show no appreciable increase
   until
   about 50C.  Conceptually, it looks pretty straight forward and, based
   on my
   Fluke 887A modifications, likely will be very stable.
  
   Since this is a very astute group, does anyone have any comments on
   the
   feasibility of this modification before I get too involved?
  
   Regards,
  
   Randy Evans
  
  
  
   Hi Randy.  Good to hear from you again.
   I have modified two 883A models and one 887A model DMMs using your
   details, with great results.  I have a model 845A null meter that is
   working fine right now, but who knows how long that will last.  I would
   surely welcome some research on modifying it with a zero-drift opamp.
   One
   concern that I would have with that mod would be that some mechanism
  would
   need to be added to retain the isolation of the recorder output and
 guard
   integrity that's afforded by the photo-modulator/demodulator circuit.
   Perhaps some kind of optically-isolated interface might be in order
  
   Some Spice runs on the original circuit would be interesting to see.
  
   Dave M
  
   ___
   volt-nuts mailing list -- volt-nuts@febo.com
   To unsubscribe, go to https://www.febo.com/cgi-bin/
   mailman/listinfo/volt-nuts
   and follow the instructions there.
  
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Matched resistors

[Randy Evans]

Andreas,

The current environment is an uncontrolled home lab.  Great variation in
temperature and humidity, hence the primary design will use the vhd200 oil
filled hermetic package resistor arrays.  I plan on evaluating for
stability and accuracy to see if I need to ovenize it to meet my voltage
standard needs. I plan on building one version type with LTZ1000s and
another with a LM399s for less demanding requirements.  The LTZ1000 will
definitely use the vhd200 resistor arrays and the LM399 may be able to use
the LTC5400 resistor arrays (or LTC1043).  The vhd200 is a leaded package
so should have minimal mechanical stress on the package (hopefully). If
necessary, and likely needed for the best stability, the circuit can be
ovenized.

Lots of testing to do.

Randy


On Sun, Jul 27, 2014 at 3:17 AM, Andreas Jahn andreas_-_j...@t-online.de
wrote:

 Hello Randy,

 until now you have not written about your design accuracy needs and about
 your environment conditions.
 (humidity + temperature controlled lab or industrial environment or simply
 your uncontrolled lab at home).

 In your measurements you should also regard humidity as a significant
 factor
 especially with resistors in plastic package like the LTC5400.
 Also the epoxy pcb is creating mechanical stress due to humidity to the
 resistors
 which can change the resistor value if not proper mechanical decoupled.
 (Difficult to mandage with SMD parts).

 I know that humidity is not easy to measure. And time constants are more in
 the range of 4-7 days which makes it even more time consuming.

 My personal opinion is that a LTC1043 based desing will perform better than
 a desing with SMD metal film resistors like the LTC5400. And a shoot out
 between
 vhd200 and LTC1043 would also be interesting depending on temperature
 range.

 By the way. The term TC tracking which is used by the resistor
 manufacturers may
 be not the same that you expect in a lab condition.
 Usually T.C. of a resistor is measured at 3 cardinal points -55 deg / 25
 deg / 125 deg.
 T.C. is then calculated out of these 3 values.
 You probably want to have the dR / dT tracking around 25 degrees which is
 not specified with this method.
 So if you specifiy T.C. tracking you should do this with your temperature
 range.

 I hope that we will get feedback on your results some day.

 With best regards

 Andreas



 Am 26.07.2014 17:56, schrieb Randy Evans:

  I would like to thank all those you supplied ideas for matching resistors.
   I have decided to test three approaches for now, the first is using
 Vishay
 vhd200 hermetically sealed foil resistors (three each at around $26 each),
 the second is using LTC5400 resistor arrays, the third is a hybrid
 approach
 using a Vishay vhd200 for the most critical resistor pair and LTC5400
 resistor arrays for the other two, and the fourth will likely be a LTC1043
 switch capacitor doubler  plus LTC5400s, although the latter is a lower
 priority.

 I plan on characterizing them over time and temperature to see the effects
 on output stability for the best approach considering cost, complexity,
 and
 accuracy.  Should be interesting if it works.  It's been taking longer
 than
 I wanted or hoped but there are only so many hours in the day and my day
 job is interfering with my play time.

 Thanks for the help,

 Randy


 On Fri, Jul 25, 2014 at 1:04 PM, Ivan.Cousins ijcous...@frontier.com
 wrote:

  Randy,

 You might want to look at:

 Digikey PN 749-1052-1-ND (qty 1, $0.89)
 or
 Digikey PN Y4485-5K/5KBCT-ND (qty 1, $22.93)

 Both parts are from Vishay.


 My advice is to build something and then measure that something.

 You are the best judge of your immediate design problem and measurement
 capabilities.

 I have found, after many years, that waiting for an Expert to hand you
 your answer does not work.

 No other Expert is as familiar with your present problem as you are.

 After a number of build-measure cycles, you may become the new Expert.

 If one waits for the ultimate answer then you may wait forever.

 The art of engineering is to get close enough.

 One can remain in the thinking stage forever, it can become an endless
 loop.

 Once you start the project by building and then measuring, you will be on
 your way to an answer, your answer.



 I am reminded of a saying everything is a transducer used here before.
 The interactions in this case are the usual temperature, stress-strain,
 humidity, resistor metal migration, etc.
 Notice that I did not include time, (long term drift), on purpose.
 It could be explained by one of the above or other, measurable quantity
 over a measurement interval.

 This is meant in the best spirit possible.
 Best of luck in your project.

 John C.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions

Re: [volt-nuts] Matched resistors

[Randy Evans]

I would like to thank all those you supplied ideas for matching resistors.
 I have decided to test three approaches for now, the first is using Vishay
vhd200 hermetically sealed foil resistors (three each at around $26 each),
the second is using LTC5400 resistor arrays, the third is a hybrid approach
using a Vishay vhd200 for the most critical resistor pair and LTC5400
resistor arrays for the other two, and the fourth will likely be a LTC1043
switch capacitor doubler  plus LTC5400s, although the latter is a lower
priority.

I plan on characterizing them over time and temperature to see the effects
on output stability for the best approach considering cost, complexity, and
accuracy.  Should be interesting if it works.  It's been taking longer than
I wanted or hoped but there are only so many hours in the day and my day
job is interfering with my play time.

Thanks for the help,

Randy


On Fri, Jul 25, 2014 at 1:04 PM, Ivan.Cousins ijcous...@frontier.com
wrote:

 Randy,

 You might want to look at:

 Digikey PN 749-1052-1-ND (qty 1, $0.89)
 or
 Digikey PN Y4485-5K/5KBCT-ND (qty 1, $22.93)

 Both parts are from Vishay.


 My advice is to build something and then measure that something.

 You are the best judge of your immediate design problem and measurement
 capabilities.

 I have found, after many years, that waiting for an Expert to hand you
 your answer does not work.

 No other Expert is as familiar with your present problem as you are.

 After a number of build-measure cycles, you may become the new Expert.

 If one waits for the ultimate answer then you may wait forever.

 The art of engineering is to get close enough.

 One can remain in the thinking stage forever, it can become an endless
 loop.

 Once you start the project by building and then measuring, you will be on
 your way to an answer, your answer.



 I am reminded of a saying everything is a transducer used here before.
 The interactions in this case are the usual temperature, stress-strain,
 humidity, resistor metal migration, etc.
 Notice that I did not include time, (long term drift), on purpose.
 It could be explained by one of the above or other, measurable quantity
 over a measurement interval.

 This is meant in the best spirit possible.
 Best of luck in your project.

 John C.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Matched resistors

[Randy Evans]

Tony,

Sorry for not reading further.  I will give it some thought. Interesting
idea.

Randy


On Thu, Jul 24, 2014 at 5:13 AM, Tony Holt vn...@toneh.demon.co.uk wrote:

 Randy,


 On 24/07/2014 04:22, Randy Evans wrote:

 Tony,

 Your improvement factor of SQRT(n) assumes that each resistor in the group
 has random changes uncorrelated to all others in the group.  For similar
 type resistors, I would think that is not likely to be true.


 Yes/,/ I'm well aware of that which is why I discussed that point further
 down in my post. It was a long post though so I don't blame you for getting
 bored and not getting that far!


  For shelf life
 stability it is likely that they all age in a similar way.  Unless the
 resistors are in a hermetic package, humidity would impact all the
 resistors in a similar manner.

 Randy

 Exactly. Since they are being used in a 1:1 divider configuration, if they
 age in a similar way, the tracking ratio stability will be good. The
 reality however is that there will be some variance between components, and
 using multiple resisters will reduce that overall variance. Part of the
 variance between individual resisters will likely follow a Guassian
 distribution and thus the improvement factor for that element will be
 SQRT(N).

 Some of the variance will likely be due to random factors which have a
 rather different distribution, probably highly skewed with long tails, and
 thus the improvement probably won't be SQRT(N). My conjecture (ok random
 speculation) is that factors such as stress differences due to
 microcracking in the ceramic substrate or at the terminations may cause
 some of the latter. Nevertheless, even though part of the variance doesn't
 follow SQRT(N) the variance will still reduce by using multiple identical
 resisters (if there are enough*). The problem is knowing how much - it
 probably can only be determined by lengthy experimentation, unless some
 good empirical data can be obtained from manufacturers or research papers.

 Another complication is that I believe that thin film resistor stability
 and TCR characteristics improve as the resistance reduces. This is not
 usually reflected in the datasheet but using multiple resistors in series
 allows lower values to be used which may perform better. On the other hand,
 thermal EMF problems may increase proportionally.

 TCR tracking is much easier to measure, so it might be interesting to see
 how it improves with increasing numbers of resisters. However, I understand
 that ratio stability is likely to be a bigger problem than TCR tracking.

 The other end of the spectrum, using a single Vishay VHD foil divider is
 certainly the simplest; however bear in mind that Vishay's stated typical
 tracking TCR of  .1ppm is just that, and the one that you buy may be
 anything but typical. And if you can work out the maximum tracking TCR from
 the VHD144/200 datasheet, you're a better man than I. My guess is that its
 probably better than .5ppm which is likely good enough for your
 application. But would it perform better than, say $30 worth of Vishay DFN,
 3ppm 4-resister networks, 1 year shelf life ratio stability  20ppm? I
 don't know.

 Of course there's nothing to stop you using multiple VHDs if you can get
 them at a good price. Ebay maybe?

 *) If all resisters are identical expcept that 1 in a 100 is markedly
 different, then any 10 will have a good chance (90%) of being identical;
 using 100 will have a good chance (64%) that at least one is different and
 thus the overall error would be at least 1/100 of the difference.

 Tony H

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Matched resistors

[Randy Evans]

 layout would need to ensure any thermal gradients apply equally
 to both legs of the divider by interleaving upper and lower resistors.

 Tony H


 On 17/07/2014 16:26, Randy Evans wrote:

 Frank,

 The high cost is my concern, although high performance demands high price
 typically.  I am trying to double the voltage reference from either an
 LM399 or LTZ1000, hence the need for precision matched resistors for a x2
 non-inverting amplifier (using a LT1151 precision op amp).  An alternative
 I am investigating is using the LTC1043 in a voltage doubling circuit as
 shown in Linear Technology app note AN 42, page 6, Figure 16.  It states
 that Vout = 2xVin +/- 5 ppm.  I am less concerned about the absolute
 accuracy than I am about the long term stability.  I assume that a high
 quality capacitor is required (low leakage, low ESR, low dielectric
 absorbtion, etc.) but the circuit does not appear to be dependent on the
 absolute value of the capacitors.  I'm not sure if the two 1uF caps  need
 to be matched.  If they do then that would be a show stopper.

 Does anyone have any experience using the LTC1043 in such a circuit?

 Thanks,

 Randy


 On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach 
 frank.stellm...@freenet.de

 wrote:
 Randy,

 resistor matched in T.C. are extremely expensive, as the manufacturer (or
 yourself) would have to select these from a batch of many samples.

 reistors with very small T.C. (1ppm/K) would do the job also, but they
 also need to be stable over time, in shelf life opereation mode, i.e.
 P10mW.

 That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
 is typically  1ppm/K and they are stable to  2ppm over 5years. But they
 cost already 80€ each, depending on tolerance.

 I made a longterm observation of these and found these parameters
 confirmed.

 Frank
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

  ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.


 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Matched resistors

[Randy Evans]

Tony,

I should have mentioned that I am primarily referring to stability, not
accuracy.  As i stated before, accuracy is relatively unimportant but
stability is essential.

Randy


On Wed, Jul 23, 2014 at 8:22 PM, Randy Evans randyevans2...@gmail.com
wrote:

 Tony,

 Your improvement factor of SQRT(n) assumes that each resistor in the group
 has random changes uncorrelated to all others in the group.  For similar
 type resistors, I would think that is not likely to be true. For shelf life
 stability it is likely that they all age in a similar way.  Unless the
 resistors are in a hermetic package, humidity would impact all the
 resistors in a similar manner.

 Randy


 On Wed, Jul 23, 2014 at 6:36 PM, Tony vn...@toneh.demon.co.uk wrote:

 Randy,

 Have you considered using multiple identical resistors to reduce the
 variance? Depending on who you believe, you can reduce the variance of the
 overall resistance by SQRT(N) where N is the number of resistors in
 series/parallel. Its not that easy to create a good search query for this
 but here is one such explanation:

 http://paulorenato.com/joomla/index.php?option=com_content;
 view=articleid=109:combining-resistors-to-improve-
 tolerancecatid=4:projectsItemid=4

 Ideally they should all come from the same batch - ie. manufactured by
 the same machine from the same batch of materials. Obviously there's no way
 to guarantee that without close liaison with the manufacturer (you did want
 10 million parts at $.10 each didn't you!) but hopefully a set of resistors
 which come off the same reel would come close.

 The absolute value isn't important however, but 'statistical gain' will
 also apply to the TCR and stability of the overall divider. The following
 assumes that both factors are similarly improved by SQRT(N), but in fact
 they may be rather better than that.

 That80€ or $108 for one sealed Vishay foil divider will buy a lot of
 lower spec parts:

 Approx 12558 x Susumu RR0510P .5%, 25ppm 0402 (Digikey, $86/10k). 6279 in
 series and parallel in each leg of the 1:1 dividerhttp://media.digikey.
 com/photos/Susumu%20Photos/RR%200402%20SERIES.jpg might reduce the
 variance to 25ppm/SQRT(6279) = .32ppm. Can't see any spec for stability,
 but it may also improve similarly. Would take a while to solder them onto
 stripboard though!

 Slightly more sensible might be 1078 x TE Connectivity RP73 1%, 10ppm
 1206 (Digikey, $100.18/1K).  Stability .5% (no qualifers in datasheet)
  = 10ppm/SQRT(539) = .43ppm, stability = 215ppm

 Or 372 x KOA Speer RN731JTTD4021B5 .1%, 5ppm (Mouser, $29/100). Stability
 not on data sheet but typical endurance is +/- .02% for 1000 hrs @ 70C
 on/off 1.5hours/.5hours.
 = 5ppm/SQRT(138) = .37ppm, endurance = 14.7ppm (Stability should be
 rather better than that). Note that the Mouser part no. is for a 25ppm part
 but their manufacturer's part number is the 5ppm part as is the
 description. Also, the price is way too high for 25ppm parts.

 Or 28 x Susumu RG2012L .01%, 2ppm (Digikey, $39.6/10). Stability not
 quoted but typical Load Life is .01% (1000 x 1.5hours on/.5hours off at 85C)
 = 2ppm/SQRT(14) = .53ppm, endurance = 27ppm

 You could also use multiple resistor networks. Eg:

 104 x Susumu RM2012B-103/103-PBVW10 .1%, 5ppm tracking, 2
 resistors/device (Digikey $104/100). Stability not quoted, endurance 500ppm
 (1000 x 1.5hours on/.5hours off at 85C)
 = 5ppm/SQRT(104) = .49ppm, endurance = 49ppm

 35 x TT Electronics SFN08B4701CBQLF7, .25%, 5ppm tracking 7
 resistors/device (Digikey, $76/25) . Stability not quoted, high temperature
 exposure  1000ppm
 = 5ppm/SQRT(122) = .52ppm

 33 x TT Electronics 668A1001DLF .5%, 5ppm tracking 8resistors/device
 (Digikey, $82/25). Stability not quoted, load life  1000ppm
 = 5ppm/SQRT(33 * 4) = .45ppm

 16 x Vishay DFN .1%, 3ppm tracking with 4 resistors/device (Digikey,
 $5.24/1). Shelf life ratio stability is specced at 20ppm (1 year at 25C).
 (That may be a typical rather than a maximum - your parts may all be much
 worse than typical). The 3ppm tracking TCR may also be a typical figure as
 its headlined in a section titled 'TYPICAL PERFORMANCE' but in the
 specification table its not qualified with '(typical)' as they sometimes do
 in other datasheets. Its hard to tell.
 = 3ppm/SQRT(32) = .53ppm shelf life stability = 3.5ppm

 5 x Vishay DSMZ metal foil dividers, .5ppm tracking max (probably
 performs rather better than this over restricted temperature range, but
 don't believe the Vishay typical figure of  .1ppm/C) (Digikey, $22.93/1).
 Shelf life ratio stability not quoted but 'typical limit' for Load Life
 ratio stability is 50ppm (2000 hours at 70C). Who knows what a typical
 limit is? Again, probably best to treat Vishay 'typical' figures with a
 pinch of salt given the experience of another poster on volt-nuts.
 = .5ppm/SQRT(5) = .22ppm, load life = 22ppm

 Interestingly Digikey quote a price of only $5400 for 1k parts for the
 similar DSM divider (1ppm tracking), which is a huge

Re: [volt-nuts] Matched resistors

[Randy Evans]

I agree that there are potentially some serious unknown issues with drift
due to time and temperature due to changes in leakage current, charge
injection, etc.  I would think some serious characterization would be
needed before this approach could be used. One approach for the charge
injection is to try and have the input voltage near Vdd/2 so the charge
injection effects are nulled out.  I'm trying to figure out how to do that
for a X2 circuit.  Any ideas?

 I talked to Vishay and they, of course, could do the resistors and I am
awaiting a quote.  They stated they would have to tune the vhd200
resistor pair to have a very low (0.2ppm/C) ratio stability .  Doable but
potentially very expensive.  Unfortunately, the maximum value of the
resistors is 20Kohms which would greatly increase the power dissipation of
the resistors, not good for long term stability.  Still working the issue.

Randy


On Tue, Jul 22, 2014 at 8:12 AM, acb...@gmx.de wrote:

 and yes, I forgot: only down-dividing of course, so to reach 10V, two
 LTZ1000 would be needed in series. advantage is that noise statistically is
 reduced by factor of about 1.4. formally also applies to drift.


  Gesendet: Montag, 21. Juli 2014 um 20:28 Uhr
  Von: Bob Smither smit...@c-c-i.com
  An: Discussion of precise voltage measurement volt-nuts@febo.com
  Betreff: Re: [volt-nuts] Matched resistors
 
  On 07/17/2014 10:26 AM, Randy Evans wrote:
   Frank,
  
   The high cost is my concern, although high performance demands high
 price
   typically.  I am trying to double the voltage reference from either an
   LM399 or LTZ1000, hence the need for precision matched resistors for a
 x2
   non-inverting amplifier (using a LT1151 precision op amp).  An
 alternative
   I am investigating is using the LTC1043 in a voltage doubling circuit
 as
   shown in Linear Technology app note AN 42, page 6, Figure 16.  It
 states
   that Vout = 2xVin +/- 5 ppm.  I am less concerned about the absolute
   accuracy than I am about the long term stability.  I assume that a high
   quality capacitor is required (low leakage, low ESR, low dielectric
   absorbtion, etc.) but the circuit does not appear to be dependent on
 the
   absolute value of the capacitors.  I'm not sure if the two 1uF caps
  need
   to be matched.  If they do then that would be a show stopper.
  
   Does anyone have any experience using the LTC1043 in such a circuit?
 
  Hi Randy,
 
  There are some other error sources that might need to be considered when
 using
  the LTC1043.
 
  I have not used the LTC1043, but note that on the data sheet there is a
 small
  charge injection at each of the switch pins. In the multiply by 2
 circuit shown
  on the data sheet they are using 1 ufd caps.  Typical charge injection
 (depends
  on voltage level) is 8 pC. With the 1 ufd caps this is 8 uV.  I assume
 there is
  some offsetting effect - but this might be a significant contributor to
 the 5
  ppm error that is mentioned.
 
  There is also a 6 nA (typical) leakage mentioned.  During the hold
 time (
  about 1 msec) of the output 1 ufd cap this comes to 6 uV.
 
  Regards,
  Bob Smither
 
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Matched resistors

[Randy Evans]

Andreas,

Since you are familiar with the LTC1043, do you know what stability over
time and temperature one could expect for the X2 circuit, assuming a high
quality low leakage capacitor was used?   Since the circuit does not appear
to be sensitive to the capacitor value, the primary change over time and
temperature would be expected to be the switch resistance I would think.
 If the circuit were fed into a high impedance buffer (LTC1151), then I
would expect the switch resistance to have minimal impact.  What do you
think?

thanks,

Randy


On Sat, Jul 19, 2014 at 8:58 AM, Andreas Jahn andreas_-_j...@t-online.de
wrote:

 Hello Randy,

 some information you will get on eevblog. (its much easier to post
 (larger) pictures there).
 Namely within the LTZ1000, LM399 and T.C. Measurements threads:

 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/
 http://www.eevblog.com/forum/projects/lm399-based-10-v-reference/
 http://www.eevblog.com/forum/projects/t-c-measurements-on-
 precision-resistors/
 http://www.eevblog.com/forum/projects/oshw-24bit-adc-
 measurement-system-for-voltage-references/
 http://www.eevblog.com/forum/projects/building-a-7-decade-
 voltage-calibrator/
 http://www.eevblog.com/forum/projects/ppmgeek!-5-5-digit-
 dvm-volt-ref-cal-%28for-arduino-or-any-uc-w-spi%29/msg296127/#msg296127

 With best regards

 Andreas

 Am 19.07.2014 16:33, schrieb Randy Evans:

  Andreas,

 Thanks for the information.  Do you have the drift chart, etc. posted
 anywhere?  that would be very interesting reading.

 Thanks,

 Randy


 On Fri, Jul 18, 2014 at 10:11 PM, Andreas Jahn 
 andreas_-_j...@t-online.de
 wrote:

  Hello Randy,

 I think the only difference is in oscillator section (and thus power
 consumption)
 and of cause the TSSOP-package.
 The LTC1043 is easily available from stock e.g. from digikey.
 The LTC6943 is more difficult to get.
 Within the Keithley 2002 LTC1043 is used.
 http://www.eevblog.com/forum/testgear/keithley-2002-8-5-
 digit-dmm-review-and-teardown/
 http://dev.xdevs.com/projects/kei2002/repository/entry/
 photos/K1/small/K2002_1-2251.jpg

 I have added a drift chart with longterm drift data.
 Note: the drift is for the whole measurement arrangement.
 It consists of 3 7V references (2 LTZ1000A and 1 LM399)
 measured via a LTC1043 divider with a 24 bit LTC2400 ADC with
 temperature compensated voltage reference AD586LQ.
 So most of the drift is related to the AD586LQ reference.
 (X-axis is in days, Y-axis in ppm)

 I get around 2 ppm drift for the LTZ1000A  over 1 year
 which I guess is mostly humidity related
 from the ADC printed cirquit board + AD586 reference drift
 and usually below 0.25 ppm standard deviation over 1000 hours.  (42
 days).
 All at unstabilized room temperature.
 I guess with resistors you will need ovenized temperature stabilisation
 to
 achieve this.

 with best regards

 Andreas

 Am 19.07.2014 05:57, schrieb Randy Evans:

   Andreas,

 That is good information, I appreciate it.  I have contacted LT
 application
 support but they have yet to get back to me on my questions except they
 did
 recommend to use the LTC6943 instead of the LTC1043.  Later generation I
 guess.

 I think i am going to try both the LTC6943 and the LT5400 resistor array
 and characterize them.  The LT5400 matching ratio looks pretty good over
 temp (0.2ppm/C) but the absolute resistor change over temp is -10 to +25
 ppm/C, a little larger than I would like for the circuit I am using.

 Randy


 On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn 
 andreas_-_j...@t-online.de
 wrote:

   Hello Randy,

 I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
 A matching of the caps is not necessary.
 In the 1/2 VIN or 1/3 VIN configuration a matching would give
 the advantage that the settling time of the cirquit is reduced.
 But in 2* VIN or inverting configuration a matching gives no advantage.
 So perhaps it is better to put a 1/2 VIN divider into a feedback loop.

 The most important point: you will need a low leakage buffer amplifier
 at
 the output.
 The caps should be low leakage foil capacitors. (polypropylene would be
 best).
 The ESR is negligible against the switch resistance of around 1000 Ohms
 And dielectric absorption would also affect only settling time.

 In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
 MKS02)
 (isolation time constant is given only with  1250 sec (3000 sec typ)).
 Buffer amplifier is a LTC1050.
 The circuit is very stable over temperature (10 - 40 deg C).
 The absolute amplification error is usually some ppm lower than exact
 2:1
 value.
 (depends somewhat on the pinning which is used so I am not shure wether
 the pins are mixed up regarding the charge compensation)

 So I dont know wether the ±1 ppm is more a stability figure than a
 absolute value.
 Even polypropylene capacitors do not change the amplification error.

 With best regards

 Andreas

 Am 17.07.2014 17:26, schrieb Randy Evans:

   Frank,

 The high cost

Re: [volt-nuts] Matched resistors

[Randy Evans]

Andreas,

Of course, I would also expect the leakage currents to change over
time/temperature and I would expect them to be the dominant error source.

Randy


On Mon, Jul 21, 2014 at 9:38 AM, Randy Evans randyevans2...@gmail.com
wrote:

 Andreas,

 Since you are familiar with the LTC1043, do you know what stability over
 time and temperature one could expect for the X2 circuit, assuming a high
 quality low leakage capacitor was used?   Since the circuit does not appear
 to be sensitive to the capacitor value, the primary change over time and
 temperature would be expected to be the switch resistance I would think.
  If the circuit were fed into a high impedance buffer (LTC1151), then I
 would expect the switch resistance to have minimal impact.  What do you
 think?

 thanks,

 Randy


 On Sat, Jul 19, 2014 at 8:58 AM, Andreas Jahn andreas_-_j...@t-online.de
 wrote:

 Hello Randy,

 some information you will get on eevblog. (its much easier to post
 (larger) pictures there).
 Namely within the LTZ1000, LM399 and T.C. Measurements threads:

 http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/
 http://www.eevblog.com/forum/projects/lm399-based-10-v-reference/
 http://www.eevblog.com/forum/projects/t-c-measurements-on-
 precision-resistors/
 http://www.eevblog.com/forum/projects/oshw-24bit-adc-
 measurement-system-for-voltage-references/
 http://www.eevblog.com/forum/projects/building-a-7-decade-
 voltage-calibrator/
 http://www.eevblog.com/forum/projects/ppmgeek!-5-5-digit-
 dvm-volt-ref-cal-%28for-arduino-or-any-uc-w-spi%29/msg296127/#msg296127

 With best regards

 Andreas

 Am 19.07.2014 16:33, schrieb Randy Evans:

  Andreas,

 Thanks for the information.  Do you have the drift chart, etc. posted
 anywhere?  that would be very interesting reading.

 Thanks,

 Randy


 On Fri, Jul 18, 2014 at 10:11 PM, Andreas Jahn 
 andreas_-_j...@t-online.de
 wrote:

  Hello Randy,

 I think the only difference is in oscillator section (and thus power
 consumption)
 and of cause the TSSOP-package.
 The LTC1043 is easily available from stock e.g. from digikey.
 The LTC6943 is more difficult to get.
 Within the Keithley 2002 LTC1043 is used.
 http://www.eevblog.com/forum/testgear/keithley-2002-8-5-
 digit-dmm-review-and-teardown/
 http://dev.xdevs.com/projects/kei2002/repository/entry/
 photos/K1/small/K2002_1-2251.jpg

 I have added a drift chart with longterm drift data.
 Note: the drift is for the whole measurement arrangement.
 It consists of 3 7V references (2 LTZ1000A and 1 LM399)
 measured via a LTC1043 divider with a 24 bit LTC2400 ADC with
 temperature compensated voltage reference AD586LQ.
 So most of the drift is related to the AD586LQ reference.
 (X-axis is in days, Y-axis in ppm)

 I get around 2 ppm drift for the LTZ1000A  over 1 year
 which I guess is mostly humidity related
 from the ADC printed cirquit board + AD586 reference drift
 and usually below 0.25 ppm standard deviation over 1000 hours.  (42
 days).
 All at unstabilized room temperature.
 I guess with resistors you will need ovenized temperature stabilisation
 to
 achieve this.

 with best regards

 Andreas

 Am 19.07.2014 05:57, schrieb Randy Evans:

   Andreas,

 That is good information, I appreciate it.  I have contacted LT
 application
 support but they have yet to get back to me on my questions except they
 did
 recommend to use the LTC6943 instead of the LTC1043.  Later generation
 I
 guess.

 I think i am going to try both the LTC6943 and the LT5400 resistor
 array
 and characterize them.  The LT5400 matching ratio looks pretty good
 over
 temp (0.2ppm/C) but the absolute resistor change over temp is -10 to
 +25
 ppm/C, a little larger than I would like for the circuit I am using.

 Randy


 On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn 
 andreas_-_j...@t-online.de
 wrote:

   Hello Randy,

 I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
 A matching of the caps is not necessary.
 In the 1/2 VIN or 1/3 VIN configuration a matching would give
 the advantage that the settling time of the cirquit is reduced.
 But in 2* VIN or inverting configuration a matching gives no
 advantage.
 So perhaps it is better to put a 1/2 VIN divider into a feedback loop.

 The most important point: you will need a low leakage buffer
 amplifier at
 the output.
 The caps should be low leakage foil capacitors. (polypropylene would
 be
 best).
 The ESR is negligible against the switch resistance of around 1000
 Ohms
 And dielectric absorption would also affect only settling time.

 In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
 MKS02)
 (isolation time constant is given only with  1250 sec (3000 sec
 typ)).
 Buffer amplifier is a LTC1050.
 The circuit is very stable over temperature (10 - 40 deg C).
 The absolute amplification error is usually some ppm lower than exact
 2:1
 value.
 (depends somewhat on the pinning which is used so I am not shure
 wether
 the pins are mixed up regarding the charge

Re: [volt-nuts] Matched resistors

[Randy Evans]

Andreas,

Thanks for the information.  Do you have the drift chart, etc. posted
anywhere?  that would be very interesting reading.

Thanks,

Randy


On Fri, Jul 18, 2014 at 10:11 PM, Andreas Jahn andreas_-_j...@t-online.de
wrote:

 Hello Randy,

 I think the only difference is in oscillator section (and thus power
 consumption)
 and of cause the TSSOP-package.
 The LTC1043 is easily available from stock e.g. from digikey.
 The LTC6943 is more difficult to get.
 Within the Keithley 2002 LTC1043 is used.
 http://www.eevblog.com/forum/testgear/keithley-2002-8-5-
 digit-dmm-review-and-teardown/
 http://dev.xdevs.com/projects/kei2002/repository/entry/
 photos/K1/small/K2002_1-2251.jpg

 I have added a drift chart with longterm drift data.
 Note: the drift is for the whole measurement arrangement.
 It consists of 3 7V references (2 LTZ1000A and 1 LM399)
 measured via a LTC1043 divider with a 24 bit LTC2400 ADC with
 temperature compensated voltage reference AD586LQ.
 So most of the drift is related to the AD586LQ reference.
 (X-axis is in days, Y-axis in ppm)

 I get around 2 ppm drift for the LTZ1000A  over 1 year
 which I guess is mostly humidity related
 from the ADC printed cirquit board + AD586 reference drift
 and usually below 0.25 ppm standard deviation over 1000 hours.  (42 days).
 All at unstabilized room temperature.
 I guess with resistors you will need ovenized temperature stabilisation to
 achieve this.

 with best regards

 Andreas

 Am 19.07.2014 05:57, schrieb Randy Evans:

  Andreas,

 That is good information, I appreciate it.  I have contacted LT
 application
 support but they have yet to get back to me on my questions except they
 did
 recommend to use the LTC6943 instead of the LTC1043.  Later generation I
 guess.

 I think i am going to try both the LTC6943 and the LT5400 resistor array
 and characterize them.  The LT5400 matching ratio looks pretty good over
 temp (0.2ppm/C) but the absolute resistor change over temp is -10 to +25
 ppm/C, a little larger than I would like for the circuit I am using.

 Randy


 On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn 
 andreas_-_j...@t-online.de
 wrote:

  Hello Randy,

 I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
 A matching of the caps is not necessary.
 In the 1/2 VIN or 1/3 VIN configuration a matching would give
 the advantage that the settling time of the cirquit is reduced.
 But in 2* VIN or inverting configuration a matching gives no advantage.
 So perhaps it is better to put a 1/2 VIN divider into a feedback loop.

 The most important point: you will need a low leakage buffer amplifier at
 the output.
 The caps should be low leakage foil capacitors. (polypropylene would be
 best).
 The ESR is negligible against the switch resistance of around 1000 Ohms
 And dielectric absorption would also affect only settling time.

 In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
 MKS02)
 (isolation time constant is given only with  1250 sec (3000 sec typ)).
 Buffer amplifier is a LTC1050.
 The circuit is very stable over temperature (10 - 40 deg C).
 The absolute amplification error is usually some ppm lower than exact 2:1
 value.
 (depends somewhat on the pinning which is used so I am not shure wether
 the pins are mixed up regarding the charge compensation)

 So I dont know wether the ±1 ppm is more a stability figure than a
 absolute value.
 Even polypropylene capacitors do not change the amplification error.

 With best regards

 Andreas

 Am 17.07.2014 17:26, schrieb Randy Evans:

  Frank,

 The high cost is my concern, although high performance demands high
 price
 typically.  I am trying to double the voltage reference from either an
 LM399 or LTZ1000, hence the need for precision matched resistors for a
 x2
 non-inverting amplifier (using a LT1151 precision op amp).  An
 alternative
 I am investigating is using the LTC1043 in a voltage doubling circuit as
 shown in Linear Technology app note AN 42, page 6, Figure 16.  It states
 that Vout = 2xVin ± 5 ppm.  I am less concerned about the absolute

 accuracy than I am about the long term stability.  I assume that a high
 quality capacitor is required (low leakage, low ESR, low dielectric
 absorbtion, etc.) but the circuit does not appear to be dependent on the
 absolute value of the capacitors.  I'm not sure if the two 1uF caps
  need
 to be matched.  If they do then that would be a show stopper.

 Does anyone have any experience using the LTC1043 in such a circuit?

 Thanks,

 Randy

   ___

 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

  ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions

Re: [volt-nuts] Matched resistors

[Randy Evans]

I figured out that VPG is Vishay Precision Group but I have not managed to
identify the vhd hermetic divider.  Could you point me to the location on
the Vishay web site?

Thanks,

Randy


On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans randyevans2...@gmail.com
wrote:

 I am not familiar with vpg or vhd terms.  I assume the former is a
 company (European?) and the latter is a model type?  Do you have a URL or
 other information to get followup information.  The 0.1 ppm tracking is
 exactly what I am looking for and I don't need absolute accuracy.

 Thanks,

 Randy


 On Fri, Jul 18, 2014 at 12:00 AM, acb...@gmx.de wrote:

 randy,
 re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
 of tempco. if you are ok with lowest available abs. accuracy it will be
 well priced, I remember having asked them for a price and it was below 50€
 for standard lead time (which can be very long). it is also fair to assume
 it would age more homogeneously than two separate resistors, also you dont
 need to think about how to keep two resistors at the same temp. make sure
 each resistor is loaded with less than 10mw, otherwise aging may be above
 what the claim in their collateral.



  Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
  Von: Frank Stellmach frank.stellm...@freenet.de
  An: volt-nuts@febo.com
  Betreff: [volt-nuts] Matched resistors
 
  Randy,
 
  resistor matched in T.C. are extremely expensive, as the manufacturer
  (or yourself) would have to select these from a batch of many samples.
 
  reistors with very small T.C. (1ppm/K) would do the job also, but they
  also need to be stable over time, in shelf life opereation mode, i.e.
  P10mW.
 
  That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
  is typically  1ppm/K and they are stable to  2ppm over 5years. But
  they cost already 80€ each, depending on tolerance.
 
  I made a longterm observation of these and found these parameters
 confirmed.
 
  Frank
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.



___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Matched resistors

[Randy Evans]

Frank,

The high cost is my concern, although high performance demands high price
typically.  I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp).  An alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16.  It states
that Vout = 2xVin +/- 5 ppm.  I am less concerned about the absolute
accuracy than I am about the long term stability.  I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors.  I'm not sure if the two 1uF caps  need
to be matched.  If they do then that would be a show stopper.

Does anyone have any experience using the LTC1043 in such a circuit?

Thanks,

Randy


On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach frank.stellm...@freenet.de
 wrote:

 Randy,

 resistor matched in T.C. are extremely expensive, as the manufacturer (or
 yourself) would have to select these from a batch of many samples.

 reistors with very small T.C. (1ppm/K) would do the job also, but they
 also need to be stable over time, in shelf life opereation mode, i.e.
 P10mW.

 That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
 is typically  1ppm/K and they are stable to  2ppm over 5years. But they
 cost already 80€ each, depending on tolerance.

 I made a longterm observation of these and found these parameters
 confirmed.

 Frank
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Matched resistors

[Randy Evans]

I am building a 10V voltage reference based on the LTZ1000 and the design
is essentially done but I am looking for a pair of matched resistors that
track very closely over temperature.  The absolute value of the pair is not
important, anything between 50K and 200K ohms would be ideal, but the
matching ratio is very important.

 I looked at the 100K ohm LT5400 quad resistor array from Linear Technology
but it has a worst case long term accelerated shelf life spec of 10 ppm (at
150C) matching ratio and long term matching ratio drift of 4ppm (at 70C).
 I would like something much tighter if possible since that would mean I
likely don't need an oven for a couple of ppm worst case accuracy over time
and temperature.  I can make the LT5400 work but I would need to do
temperature characterization and circuit compensation.  Doable but
undesirable.

Does anyone have any ideas for a good ratio matched resistor pair,
hopefully not too expensive?

Thanks,

Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Latching Low Thermal EMF Relays

[Randy Evans]

That is an assembly but I am looking for an individual relay part that I
can put on a PCB.

Randy


On Fri, Jul 11, 2014 at 7:15 AM, Wim de Jong wim.de.jong...@solcon.nl
wrote:

 The http://www.transmille.co.uk/8500.htm

 Wim de Jong

 ___
  volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts and follow the instructions there.
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/
 mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Buying HP-3458A

[Randy Evans]

That e-mail I referenced is several years old.  i believe the current
repair price is just over $2800.

Randy


On Sat, Jul 5, 2014 at 10:49 PM, John Phillips john.philli...@gmail.com
wrote:

 ​They do really offer that service as​ long as you send them a complete
 meter... No missing parts. Well they will take a few missing screws and
 such. My experience with them is they charge the same no mater what need to
 be fixed. Not sure what the price is, there prices are country dependent. I
 thought it was a little more than $2200 last I checked.


 On Sat, Jul 5, 2014 at 4:08 PM, Randy Evans randyevans2...@gmail.com
 wrote:

  I am in the market for a used HP-3458A and, in researching past
 messages, I
  came across an interesting question:
 
  *Chris Erickson* ericksonc2 at comcast.net
  volt-nuts%
 
 40febo.com?Subject=Re%3A%20%5Bvolt-nuts%5D%203458A%20questionsIn-Reply-To=%3C001b01cc7960%24a15d2840%24e41778c0%24%40net%3E
  
  *Thu Sep 22 19:48:41 UTC 2011*
 
  If Agilent will fix everything, bring it up to specs, and calibrate it no
 
  matter what's wrong with it for $2200, then why would I spend $5000-6000
 or
 
  more for one that is in good shape - even if calibrated? Just grab the
  first
 
  bargain that comes along for $1500-3000, send it straight to Agilent and
 be
 
  money ahead. Seems the better course of action to me if that price is
 
  accurate - do they really offer this service?
 
 
 
 
  I could not find an answer to this question but it does beg the question.
   Does nayone have an answer as to why not buy the cheapest unit and send
 it
  in for repair?
 
 
  Thanks,
 
 
  Randy Evans
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.
 



 --
 John Phillips
 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

[volt-nuts] Fluke calibration Book

[Randy Evans]

Here is a link to a book from Fluke titled 'Calibration - Philosophy in
Practice'.  A little dated (1980) but interesting to read.

*https://archive.org/details/Calibration-PhilosophyInPractice
https://archive.org/details/Calibration-PhilosophyInPractice*


Randy Evans
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Datron 1082

[Randy Evans]

I just took out the battery and it is a Tenergy 3.6 VDC 1200mAH ER14250
with tabs welded on.

Randy


On Tue, Apr 22, 2014 at 9:08 PM, Randy Evans randyevans2...@gmail.comwrote:

 Todd,

 That does look like the battery in my 1082. I don't see any markings on
 the battery in my unit but I can't see the back side until I remove it.

 I assume the original was 3.6 VDC also but I'm not sure how to verify
 that.

 Thanks for the help.

 Randy


 On Tue, Apr 22, 2014 at 7:07 PM, T. Micallef tmical...@gmail.com wrote:

 Randy Evans randyevans2688@... writes:

 
  The schematic of the Datron 1071 DMM seems to be very similar to the
 Datron
  1082 but I'm sure there are differences.  Unfortunately, I have not been
  able to locate the 1082 Service Manual with the parts lists and
 schematics.
   The 1071 manual does have a similar or identical battery but I can't
 find
  the part number in the 1071  parts list.  Does anyone know the part
 number
  of the memory battery in the 1082 or 1071, or the characteristics; e.g.,
  voltage and A-H rating?
 
  Thanks,
 
  Randy Evans AE6YG
 
  On Mon, Apr 21, 2014 at 8:32 PM, Tom Knox actast@... wrote:
 

 I popped the top off of my mothballed 1071 and it looks like a 1/2AA
 battery
 based on physical measurements. It looks like the one in the following
 link

 http://www.zbattery.com/Tadiran-TL-5151-with-tabs-1-2-AA-Lithium-Battery

 Todd

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.



___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.

Re: [volt-nuts] Datron 1082

[Randy Evans]

The schematic of the Datron 1071 DMM seems to be very similar to the Datron
1082 but I'm sure there are differences.  Unfortunately, I have not been
able to locate the 1082 Service Manual with the parts lists and schematics.
 The 1071 manual does have a similar or identical battery but I can't find
the part number in the 1071  parts list.  Does anyone know the part number
of the memory battery in the 1082 or 1071, or the characteristics; e.g.,
voltage and A-H rating?

Thanks,

Randy Evans AE6YG


On Mon, Apr 21, 2014 at 8:32 PM, Tom Knox act...@hotmail.com wrote:

 Sorry I wasn't clear. I think the errors you are experiencing are because
 the memory battery is gone, so it won't matter now, this is for saving the
 cal data during future replacement to avoid these problems again.
 Best Wishes;
 Thomas Knox



  Date: Mon, 21 Apr 2014 19:59:29 -0700
  From: randyevans2...@gmail.com
  To: volt-nuts@febo.com
  Subject: Re: [volt-nuts] Datron 1082
 
  Tom,
 
  I would think with 0.08 VDC the battery is dead and all the memory is
 gone.
   Do you think it would make any difference if I paralleled the leads
 with a
  new one?  I don't have a parts list to know what type the battery is so
  it's going to be a challenge to find a direct replacement.  Wish I had a
  manual.
 
  Randy
 
 
  On Mon, Apr 21, 2014 at 7:54 PM, Tom Knox act...@hotmail.com wrote:
 
   Randy I would say from my experience with Datron there is about 90%
 chance
   the battery and recal will solve the problem. I would modify the
 battery
   with a coupe sets of leads that are long enough so you can install a
 new
   while the old battery is still in circuit.
   Best Wishes;
   Thomas Knox
  
  
  
Date: Mon, 21 Apr 2014 19:23:35 -0700
From: randyevans2...@gmail.com
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Datron 1082
   
I believe the voltages are correct but I have no schematics or
troubleshooting instructions to confirm.  I do see what looks like a
battery in the memory section of the 1082 and it measures 0.08 VDC.
 Not a
good sign.  I am really hoping someone has a Datron 1082 Service
 manual
with schematics that they can steer me to, preferably a soft copy so
 I
   can
better troubleshoot the unit.  It might just need a new battery
 (plus a
re-cal) to get it going again but I hate going blind.
   
Randy
   
   
On Mon, Apr 21, 2014 at 8:15 AM, Tom Knox act...@hotmail.com
 wrote:
   
 As with many products of this age the tantalum caps are a common
 point
   of
 failure in the 1082.
 Although this current problem sounds like a memory battery.

 Thomas Knox



  Date: Mon, 21 Apr 2014 11:03:56 -0400
  From: cfhar...@erols.com
  To: volt-nuts@febo.com
  Subject: Re: [volt-nuts] Datron 1082
 
  Just in case you haven't yet: Always start any investigation with
  checking the power supply for voltage and ripple.  Test the main
  electrolytic capacitors for capacitance, and ESR.
 
  Nothing in the unit's self testing ability can be trusted if the
  power supply is putting out large amounts of ripple, or is at the
  wrong voltage.
 
  -Chuck Harris
 
  Randy Evans wrote:
   I have a Datron 1082 DMM that just recently stopped working.
  When
   I
 power
   up, it gives a FAIL message on the front panel.  I found a
   flowchart
 in
   an abbreviated servicing manual that indicates it's from a
 failure
   of
 the
   Check for uncorrupted calibration store.  I Assume this
 likely
   means
 the
   cal tables are corrupted?  Unfortunately, I don't have
 sufficient
   information (e.g., schematics) to do any further
 troubleshooting.
Can
   anyone help with a complete servicing manual and/or further
   diagnostic
 help?
  
  
   I did download the Datron 1071DMM  OS manual from K04BB but I
   don't
 know
   how similar it is to the 1082.  Can anyone comment on what the
 differences
   are?
  
  
  
   Thanks,
  
  
  
   Randy Evans
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
   https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
  
   ___
   volt-nuts mailing list -- volt-nuts@febo.com
   To unsubscribe, go to
   https://www.febo.com/cgi-bin/mailman

Re: [volt-nuts] Datron 1082

[Randy Evans]

I believe the voltages are correct but I have no schematics or
troubleshooting instructions to confirm.  I do see what looks like a
battery in the memory section of the 1082 and it measures 0.08 VDC. Not a
good sign.  I am really hoping someone has a Datron 1082 Service manual
with schematics that they can steer me to, preferably a soft copy so I can
better troubleshoot the unit.  It might just need a new battery (plus a
re-cal) to get it going again but I hate going blind.

Randy


On Mon, Apr 21, 2014 at 8:15 AM, Tom Knox act...@hotmail.com wrote:

 As with many products of this age the tantalum caps are a common point of
 failure in the 1082.
 Although this current problem sounds like a memory battery.

 Thomas Knox



  Date: Mon, 21 Apr 2014 11:03:56 -0400
  From: cfhar...@erols.com
  To: volt-nuts@febo.com
  Subject: Re: [volt-nuts] Datron 1082
 
  Just in case you haven't yet: Always start any investigation with
  checking the power supply for voltage and ripple.  Test the main
  electrolytic capacitors for capacitance, and ESR.
 
  Nothing in the unit's self testing ability can be trusted if the
  power supply is putting out large amounts of ripple, or is at the
  wrong voltage.
 
  -Chuck Harris
 
  Randy Evans wrote:
   I have a Datron 1082 DMM that just recently stopped working.  When I
 power
   up, it gives a FAIL message on the front panel.  I found a flowchart
 in
   an abbreviated servicing manual that indicates it's from a failure of
 the
   Check for uncorrupted calibration store.  I Assume this likely means
 the
   cal tables are corrupted?  Unfortunately, I don't have sufficient
   information (e.g., schematics) to do any further troubleshooting.  Can
   anyone help with a complete servicing manual and/or further diagnostic
 help?
  
  
   I did download the Datron 1071DMM  OS manual from K04BB but I don't
 know
   how similar it is to the 1082.  Can anyone comment on what the
 differences
   are?
  
  
  
   Thanks,
  
  
  
   Randy Evans
  ___
  volt-nuts mailing list -- volt-nuts@febo.com
  To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
  and follow the instructions there.

 ___
 volt-nuts mailing list -- volt-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 and follow the instructions there.

___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.