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

[Tom Miller]

How about copying the contents of the old nvram to the new one?


- Original Message - 
From: "David C. Partridge" 

To: "'Discussion of precise voltage measurement'" 
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 expected!  Processor must detect 
cal mode by writing to NVRAM - if succeeds, then in Cal mode??? Maybe


Is there some obscure incompatability between the DS1220AD and the 
DS1220Y???


Dave

-Original Message-
From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. 
Partridge

Sent: 02 November 2017 18:23
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] Prema 6048 Cal switch confusion

I've got a Perma 6048 that I've trying to put into Cal mode.  It just 
won't!


The switch on the rear panel works OK, AFAICT when in the Cal position it 
connects ~WE on the DS1220 (pin 21) and ~W on the $864 SRAM (pin 27) to a
4K7 pullup to +5V and to the output of an LS00 which should be strobing 
the
Write lines low as needed.   I can't see any way in which the processor 
can
be informed of the switch setting!  In measure mode it just connects ~WE 
on the DS1220 to a 10k pullup to +5V.


The schematic is on page 120 (Figure 11.4) of the user manual and also 
page

9-7 of the service manual.

Clearly I'm missing something - as a friend reports that his does go into 
cal mode.


Confused ...
Thanks
Dave

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Re: [volt-nuts] PCBs with ceramic substrates

[Tom Miller]

Ceramic plates are even used in armor to stop armor piercing projectiles.

Lots of applications.

- Original Message - 
From: "Chuck Harris" 

To: "Discussion of precise voltage measurement" 
Sent: Wednesday, April 12, 2017 5:04 PM
Subject: Re: [volt-nuts] PCBs with ceramic substrates



Simple, ceramic is a generic term, like car.

And, ceramic substrates are available in all manner
of different thicknesses, densities, and materials.

Like every other engineering material, you decide what
characteristics are important to you, and you pick the
appropriate material that meets those characteristics.

If you work outside of the envelope of that material's
capabilities, the results will be disappointing.

You were opining that ceramic was too brittle, and
breakable and shouldn't be used for metrology work, I
disagreed, and attempted to enlighten you with tales of
some ceramics that you would be hard pressed to break,
even with repeated blows from a hammer.

I could tell you of transparent ceramics that are
amazingly hard, and strong.

I could go further and tell of other ceramics where you
can crumble brick sized blocks with light finger pressure.

And I could tell you of still other ceramics that you can
heat white hot with a torch, and then in a fraction of a
second, press the glowing section against your arm without
it even feeling warm.

Which could lead some to say: ceramics are cool!

But as they say, you can lead a horse to water, but you
cannot make him drink.

-Chuck Harris

cheater00 cheater00 wrote:

What can account for this difference between your and my experience
and what Chuck said?


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Re: [volt-nuts] Basic question concerning voltage references

[Tom Miller]

I believe you can get 7-1/2 digits out of the 3457A via the HPIB port.

Regards,
Tom

- Original Message - 
From: "Russ Ramirez" 

To: "Discussion of precise voltage measurement" 
Sent: Monday, February 20, 2017 2:26 PM
Subject: Re: [volt-nuts] Basic question concerning voltage references



My question is partly based on a real situation where I have 3 DMMs of
decent quality Keithley 2000, 34970A (34401A), and 3457A that all agree
with a good quality voltage reference that is exceeding its ppm/degree C
spec as far as I am able to tell. I felt that this was telling me that I
would need a 3458A to know how much closer to 10V the reference was at 
this
point. A quick calculation of 20 bits of ADC for example told me that I 
was
looking at 9.5 uV of resolution, or 0.6 uV at 24 bits *noise free*, etc. 
so
it did not seem to be entirely unreasonable to see the LSD of a 6 1/2 
digit

DMM be higher than 1 or 2 counts.

Russ

On Mon, Feb 20, 2017 at 12:57 PM, m k  wrote:


On 20/02/2017 18:46, Russ Ramirez wrote:
> I very much enjoy what is shared here. It has led me down the path of
> learning more about Metrology in general and the pointers to Flukecal
site
> from here are appreciated.
>
> My question is this. If I measured a 10 volt reference known to be good
to
> 8 1/2 digits, but with the LSD being > 0, assuming a transfer standard
with
> traceability and documented uncertainties etc, would a 6 1/2 digit
> voltmeter read 10.0 volts, or round up to the limits of its AD
> converter resolution; say X uV over 10.0 volts?
>
> I hope this is not too basic a question.
>
> Russ
> ___
>
Hi Russ,

some voltmeters will supply extra digits in the output they provide, but
whether they are of any use depends upon how
stable the reference is in that particular 6.5 digit dvm, unfortunately 
it

needs a dvm with better capability to prove
if those digits are believable.


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Re: [volt-nuts] fluke 731b battery pack

[Tom Miller]

If they are integrated with the device, the manufacturer must certify they 
have tested the device and proved it can not cause a fire. If you change the 
NiCd battery to a LiFe system, you will fail that requirement. When you 
ship, you must certify there is no hazmat item in your package. There is a 
minimum Wh capacity allowed but I am not sure what it is. Not much from 
memory.







- Original Message - 
From: "David" 

To: "Discussion of precise voltage measurement" 
Sent: Wednesday, August 03, 2016 5:29 PM
Subject: Re: [volt-nuts] fluke 731b battery pack



Does that restriction apply to batteries which are integrated with a
device?  I thought it only applied to separate cells.

On Wed, 03 Aug 2016 17:20:00 -0400, you wrote:

I like the LiFe idea except for the restrictions on shipping by air or 
USPS.


That shouldn't be too much of a problem for most that have access to a 
local

cal lab.

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Re: [volt-nuts] fluke 731b battery pack

[Tom Miller]

I like the LiFe idea except for the restrictions on shipping by air or USPS.

That shouldn't be too much of a problem for most that have access to a local 
cal lab.





- Original Message - 
From: "David" 

To: "Discussion of precise voltage measurement" 
Sent: Wednesday, August 03, 2016 5:08 PM
Subject: Re: [volt-nuts] fluke 731b battery pack



On Wed, 3 Aug 2016 16:34:31 -0400, you wrote:


Eric wrote:


NiMH cells seem to work in the 731b so I'd prefer to use them over NiCd
because of the higher capacity and lower toxicity of potential leaks. Is
there a downside to doing this?


In my experience, good NiCDs are preferable to NiMHs.  Good NiCds have
substantially lower self-leakage than NiMHs (this is true even of the
"NEW!! Low-discharge!!" NiMHs).  NiCds also don't degrade nearly as fast
if they are left too long on trickle charge.   Both of these features
translate directly into increased life for the NiCds.  NiCds are also
quieter, and capable of larger current drains, due to their lower
internal (series) resistance (high current is not really an issue in
your application).


That is my experience as well however I do like the better low
discharge NiMH cells.  Some are better than other though.


Consumer-type NiCds may suffer from the problem PHK noted (poor quality
due to low production volumes), but there are still many industrial and
military applications that specify NiCDs for some or all of the reasons
given above.  Excellent NiCds are readily available -- just look for
aerospace-grade parts rather than consumer batteries.


Low leakage and high temperature NiCd cells seem to last a lot longer
than other types and you will not find any consumer versions of these
but the price is high.


Many built-in charging circuits are crude and leave the batteries on a
trickle current that is really too high, particularly given the
temperatures inside electronic instruments.  So whichever batteries you
choose, plan on redesigning the charging circuit.

That brings up the possibility of using either LiFePO4 or SLA (sealed
lead-acid) batteries -- if you have to redesign the charging circuit
anyway, you can just as easily design it for LiFePO4 or SLA.

I have not evaluated the 731B power supply in particular, but LiFePO4
would be my presumptive choice unless I encountered an insurmountable
obstacle.

Best regards,

Charles


I looked at the schematic and is seems feasible without excessive
effort.  Either the existing simple series preregulator can be
modified or replaced allowing it to both charge the battery (through a
blocking diode) and power the instrument or a completely separate
power charging circuit can be added in parallel.

The difficulty of maintaining charge in a backup application using
NiMH cells would lead me to consider LiFePO4 cells instead.  The only
serious difficulty would be preventing excessive discharge which will
ruin a lithium (or PbSO4) based rechargeable battery in short order.
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Re: [volt-nuts] fluke 731b battery pack

[Tom Miller]

NiMH does not do too well in float charge conditions and that is the main 
state a 731B will spend its time.


Regards,
Tom

- Original Message - 
From: "Eric Garner" 

To: "Discussion of precise voltage measurement" 
Sent: Wednesday, August 03, 2016 1:27 PM
Subject: [volt-nuts] fluke 731b battery pack



So I managed to get one of the Fluke 731b's mentioned on the list a while
back. It was a little more chewed up than the description in the auction
led me to believe:

https://plus.google.com/u/0/112871219575380932919/posts/iDWyzwYYRdj?pid=6314634305601690930=112871219575380932919

but it appears to be functional.

The NiCd pack appears to have leaked some time in the past and was 
removed,

which is fine since I was going to replace the batteries anyway.

Looking through the archives, replacement battery packs for the 731b has
been a popular topic but I have some questions that remain open.

1. NiMH cells seem to work in the 731b so I'd prefer to use them over NiCd
because of the higher capacity and lower toxicity of potential leaks. Is
there a downside to doing this?

2. If I go with NiMH, is there a manufacturer that's prefered? reading
reviews of NiMH cells online leads me to believe that some manufacturers
(Tenergy) have lower quality and are less reliable.

3. If I go with NiCd would you expect problems if I used larger cells 
(4/5A

vs 2/3A)




thanks

--Eric
_
Eric Garner
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Re: [volt-nuts] Just back from cal

[Tom Miller]

You really won't know what is going on until you do the next calibration 
cycle and examine the as received data for both units. Or find someone with 
a better meter or reference and compare them.


Who did the calibration?

You might leave both units powered up for a few days/weeks and see how they 
behave together. Also, you are two degrees C above you lab calibration 
temperature. That could add to the uncertainty.





- Original Message - 
From: "Joseph Gray" 

To: "Discussion of precise voltage measurement" 
Sent: Thursday, April 07, 2016 11:20 PM
Subject: [volt-nuts] Just back from cal



In February, I sent my HP 3457A in for cal. In late March, I sent my
EDC VS330 DC Voltage Reference in for cal. Today, I just got the VS330
back and thought I'd compare the two instruments.

Both instruments have been on for a couple of hours. It is about 25 C
in the room.

Setting 10.0 on the VS330, I measure 9.99891 VDC on the 3457A.

According to the manual, on the 30 VDC range, the 90 day spec is
0.0035% of reading, plus 19 counts.

The VS330 lists the "Limit of error accuracy" as 0.003% of setting
plus 0.001% of range (30 V range). The "Calibration accuracy" is
0.002% of setting plus 0.0005% of range.

Now, if we take the worst case for both instruments, what I am reading
is marginally inside the total error for both instruments. However,
considering that both instruments were recently calibrated and
adjusted, I would expect much better.

The report on the 3457A, dated 16 Feb says the 30 VDC range read
29.9991 VDC. The report on the VS330, dated 31 Mar says 10 VDC read
10.0001 VDC. Both instruments required adjustment.

These numbers would lead me to believe that I should be getting a lot
closer agreement to 10 VDC for both of these instruments. Am I
expecting too much?

Joe Gray
W5JG
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Re: [volt-nuts] Fluke 5200A instability...

[Tom Miller]

How about any aluminum electrolytics that might be used for coupling 
capacitors? I had a problem with a DC reference that had some aluminum 
electrolytic caps that were leaky and caused feedback problems.


If memory holds, they were in the 10 to 30 uF range.

Just a thought.

Tom

- Original Message - 
From: Chuck Harris cfhar...@erols.com

To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Tuesday, July 28, 2015 11:35 PM
Subject: [volt-nuts] Fluke 5200A instability...



Before I spend a lot more time on it, does anyone have any experience
with the Fluke 5200A's feedback loop oscillating when in the 100Hz band
position?

Mine started to oscillate at about a 1/2Hz rate a while back. It is two
to three orders of magnitude better when in the 1KHz and higher band
positions.

I can tell it is oscillating because if I watch the 3 least significant
digits on my 3456A voltmeter, in the AC position, they keep repeating
over and over and over... sort of fits a 1-2-3-1-2-3... count.

I have replaced the bad capacitors in the power supply, and on
a few of the boards.  I have checked the supplies for voltage and
ripple, and AFAIK they are ok.

I tested the 2uf mylar integrator cap that is employed while in the
100Hz band, and replaced more than a few carbon composition resistors
that were between 20 and 50% out of tolerance with no apparent affect.

The carbon composition resistors I replaced were used to digitally
adjust the gain of the integrator, so seemed likely to have an effect
on the stability criterion of the feedback loop..

The DC Reference voltage seems to be very stable, and can be selected
up and down with the voltage selection switches.

I have tested all of the tantalums for shorts, and found none.

I am running out of ideas.

TIA,

-Chuck Harris
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Re: [volt-nuts] Oven thermal insulation

[Tom Miller]

You might look at AeroGel. Example here.

http://www.ebay.com/itm/Aspen-Aerogel-SPACELOFT-Insulation-Hydrophobic-Mat-10-x-14-Sample-10mm-/171203844436?pt=LH_DefaultDomain_0hash=item27dc8b5954




- Original Message - 
From: Randy Evans randyevans2...@gmail.com

To: volt-nuts@febo.com
Sent: Monday, July 06, 2015 8:43 PM
Subject: [volt-nuts] Oven thermal insulation



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

[Tom Miller]

Did you remove the two holes?

:)

- Original Message - 
From: Mark Sims hol...@hotmail.com

To: volt-nuts@febo.com
Sent: Friday, August 29, 2014 1:53 PM
Subject: [volt-nuts] Fluke 5200A extender board.


5200A extender cables are a go!   Connectors and boards are on order (from 
a different board fab in Hong Kong this time).  One board goes on each end 
of the extender.  Boards are connected by a 50 pin and 40 pin ribbon 
cable.









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

[Tom Miller]

Would that be at the maximum temperature? Service would be at room temp.

Sounds like a good excuse, right?


- Original Message - 
From: Mark Sims hol...@hotmail.com

To: volt-nuts@febo.com
Sent: Friday, August 29, 2014 2:28 PM
Subject: [volt-nuts] Fluke 5200A extender board.


Those are not holes...  they are polarity markers on the silkscreen for 
the connectors.
I do have one concern about doing the extender with ribbon cable.  It is 
rated for 300V and three of the card slots do have  300V on them.

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

[Tom Miller]

Learn something new every day. Thanks.

- Original Message - 
From: Mike S mi...@flatsurface.com

To: volt-nuts@febo.com
Sent: Friday, August 29, 2014 2:27 PM
Subject: Re: [volt-nuts] Fluke 5200A extender board.



On 8/29/2014 2:16 PM, Tom Miller wrote:

Did you remove the two holes?

:)


You mean the two pin 1 markers on the silkscreen?
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Re: [volt-nuts] Fluke 732A battery module (and possible circuitreplacement)

[Tom Miller]

It might be nice to do a lithium pack including all the safety controls. The 
down side is you would not be able to ship it by air.


Tom

- Original Message - 
From: Mark Sims hol...@hotmail.com

To: volt-nuts@febo.com
Sent: Monday, August 25, 2014 9:10 PM
Subject: [volt-nuts] Fluke 732A battery module (and possible 
circuitreplacement)



I have a 732A that is missing its battery module.  Does anybody have or 
know of a source for a replacement?
Also,  would there be any interest in a replacement circuit assembly for 
the battery module?  It would probably consist of a small board that plugs 
into the 2x6 pin edge connector and another small board with the ballast 
lamp/diode/resistor/thermistors and connections for the 
battery/switch/external power jack.  The two boards would be connected by 
a short ribbon cable and would allow one to add batteries to a 732A that 
is missing the battery module.  It would not be a complete battery module 
with the metal frame and backplate...

___


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Re: [volt-nuts] HP3458A CAL ram data dumper program

[Tom Miller]

Hi Mark,

Is it possible the program could create a .bin or .hex file that could be 
used to burn a backup NVRAM on an external programmer?


I would love to have a copy if possible. While I don't yet have a 3458A, it 
is on my wish list awaiting the necessary funds to build up and for that 
once in a while good deal.


Regards,
Tom

- Original Message - 
From: Mark Sims hol...@hotmail.com

To: volt-nuts@febo.com
Sent: Thursday, August 21, 2014 9:33 PM
Subject: [volt-nuts] HP3458A CAL ram data dumper program


I have the GPIBKIT version of my HP3458A cal ram data dumper program 
available.  If you want to try a copy shoot me an email.   If  it works 
out, I'll see if John wants to include it in the standard toolkit 
distribution.
You will need to download GPIB tool kit from the KE5FX.COM web site,  run 
the tool kit configuration program (PROLOGIX.EXE)  to setup it up for your 
interface (it works with Prologix and NI compatible interfaces),  copy my 
HP3458.EXE program to the GPIBKIT directory and run it.  Check the 
comments at the start of HP3458.CPP for some info.  Run HP3458.EXE without 
any command line arguments for program usage help.

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Re: [volt-nuts] 34401A Why 10M ohm default i/p resistance?

[Tom Miller]

Think HV Probe. Many of the accurate ones want to see a 10 meg input.

Also, some meters change input impedance depending on the selected range.

T

- Original Message - 
From: Tony vn...@toneh.demon.co.uk

To: volt-nuts@febo.com
Sent: Thursday, April 10, 2014 10:23 AM
Subject: [volt-nuts] 34401A Why 10M ohm default i/p resistance?


There is no suggestion in the specifications for the 34401A that the 
accuracy suffers by selecting 10G ohm input resistance on the .1 to 10V 
range so why would they make 10M ohm the default? I can think of very few 
cases where having the 10M ohm i/p resistor switched  in is better for 
accuracy than not.


On the other hand 10M is sufficiently low to produce significant errors on 
a 6 1/2 digit DVM for sources with resistances as low as 10 ohms. 
Measuring 1V divided by a 100k/100k ohm divider for example causes a .5% 
error - 502.488mV instead of 500.000mV. That might not be a problem but I 
wouldn't be surprised if this catches a lot of people out (including me) 
when not pausing to do the mental arithmetic to estimate the error. It's 
just too easy to be seduced by all those digits into thinking you've made 
an accurate measurement even though you discarded those last three digits.


And if it's not a problem then you probably don't need an expensive 6 1/2 
digit meter in the first place.


It's a small point I agree but it can get irritating to have to keep going 
into the measurement menus to change it when the meter is turned on when 
measuring high impedance sources (e.g. capacitor leakage testing).


It can't be to improve i/p protection as 10M is too high to make any 
significant difference to ESD and in any case there is plenty of other 
over-voltage protection. OK. it provides a path for the  DC amplifier's 
input bias current, specified to be  30pA at 25 degrees C, but I imagine 
that varies significantly from one meter to the next, and with 
temperature, so not useful for nulling out that error.


So why would they do this? Could it be psychological? By limiting the 
drift caused by the i/p bias current to 300uV max when the meter is left 
unconnected? A voltmeter with a rapidly drifting reading (several mV/s) 
when not connected to anything is a bit disconcerting and would probably 
lead to complaints that the meter is obviously faulty to users who are 
used to DVMs which read 0V when open circuit - because they have i/p 
resistance  10G ohms and don't have the resolution to show the offset 
voltage caused by the i/p bias current.


Personally I'd have though that the default should be the other way 
round - especially given that there is no indication on the front panel or 
display as to which i/p resistance is currently selected.


Any thoughts? What do other meters do?

Tony H
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Re: [volt-nuts] 34401A Why 10M ohm default i/p resistance?

[Tom Miller]

Don't forget. There is accuracy and then precision. You should not confuse 
the two.


And many things use high voltages 1kv besides old crts.

T

- Original Message - 
From: Brent Gordon volt-n...@adobe-labs.com

To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Thursday, April 10, 2014 4:16 PM
Subject: Re: [volt-nuts] 34401A Why 10M ohm default i/p resistance?


Pure conjecture:  So that the reading on the 34401A matches that on a $20 
DVM.


Or stated differently:  So that the input impedance is the same as other 
DVMs.


Brent

On 4/10/2014 8:23 AM, Tony wrote:
There is no suggestion in the specifications for the 34401A that the 
accuracy suffers by selecting 10G ohm input resistance on the .1 to 10V 
range so why would they make 10M ohm the default? I can think of very few 
cases where having the 10M ohm i/p resistor switched  in is better for 
accuracy than not.


On the other hand 10M is sufficiently low to produce significant errors 
on a 6 1/2 digit DVM for sources with resistances as low as 10 ohms. 
Measuring 1V divided by a 100k/100k ohm divider for example causes a .5% 
error - 502.488mV instead of 500.000mV. That might not be a problem but I 
wouldn't be surprised if this catches a lot of people out (including me) 
when not pausing to do the mental arithmetic to estimate the error. It's 
just too easy to be seduced by all those digits into thinking you've made 
an accurate measurement even though you discarded those last three 
digits.


And if it's not a problem then you probably don't need an expensive 6 1/2 
digit meter in the first place.


It's a small point I agree but it can get irritating to have to keep 
going into the measurement menus to change it when the meter is turned on 
when measuring high impedance sources (e.g. capacitor leakage testing).


It can't be to improve i/p protection as 10M is too high to make any 
significant difference to ESD and in any case there is plenty of other 
over-voltage protection. OK. it provides a path for the DC amplifier's 
input bias current, specified to be  30pA at 25 degrees C, but I imagine 
that varies significantly from one meter to the next, and with 
temperature, so not useful for nulling out that error.


So why would they do this?


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Re: [volt-nuts] FET HP3456A

[Tom Miller]

Borrow Q108 (or any of the like devices) to test your hypothesis. It is just 
used as a low leakage protection diode. You can replace Q108 with almost any 
n-ch fet.


Tom

- Original Message - 
From: Tony Greene tonygreen...@inbox.com

To: volt-nuts@febo.com
Sent: Tuesday, April 01, 2014 10:13 PM
Subject: [volt-nuts] FET HP3456A



I have been troubleshooting a HP3456A voltmeter.

Its giving a stange fault, but I beleive I have nailed it down.  The unit 
is reading +10.0 volts input at +9.99661 volts.  If you reverse the 
input, it reads correct at -10.0 volts. All other ranges read correct 
on either polarity.


What I need is a source for the FET  A20 Q109 or a suitable substitute. 
Its HP part number 1855-0298, it was made originally by USA mfg 02883 - 
Siliconix, Inc, Santa Clara, CA.  It crosses to NSN 5961-01-135-1324.  And 
Vishay has bought them and the part number is now obselete.



FREE 3D EARTH SCREENSAVER - Watch the Earth right on your desktop!
Check it out at http://www.inbox.com/earth


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Re: [volt-nuts] 3455A ROMS

[Tom Miller]

KO4BB.com has the images for the 3455A.

Here: 
http://ko4bb.com/manuals/index.php?dir=04)_ROM_Images_and_Drivers/HP_3455A


Regards,
Tom


- Original Message - 
From: Sam Reaves sam.rea...@gmail.com

To: volt-nuts@febo.com
Sent: Monday, March 31, 2014 10:04 AM
Subject: [volt-nuts] 3455A ROMS



I have a HP3455A that by all appearances has lost its cookies perhaps due
to bad ROMS. Does anyone have these rom images and a procedure to
replace/refresh them?

Sam
W3OHM
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Re: [volt-nuts] 3458a RAM batteries - longer life if unit is continually powered?

[Tom Miller]

Only on the newer (AB  AD) Dallas (Maxim) parts. All the old ones (Y) do 
not have that feature.


Tom M.

- Original Message - 
From: Tom Knox act...@hotmail.com

To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Thursday, March 27, 2014 12:59 PM
Subject: Re: [volt-nuts] 3458a RAM batteries - longer life if unit is 
continually powered?



Date Codes can be misleading because most of this style of chip does not 
connect to the battery until the first power up cycle. So evl


Thomas Knox




Date: Thu, 27 Mar 2014 17:33:17 +0100
From: frank.stellm...@freenet.de
To: volt-nuts@febo.com
Subject: [volt-nuts] 3458a RAM batteries - longer life if unit is 
continually powered?


Hi,

the DALLAS datasheet specifies 10 years data retention. Quite obviously,
that's the unpowered time.

That time includes self discharge and RAM sustaining currents.

self discharge and RAM supply current will be of the same order, i.e. 
1µA, I assume from experience.
And I assume also, that those currents will vary over samples, i.e. over
samples of battery and RAM.

Recently, there was the case, where the CAL RAM was still alive after 24
years (instrument vintage 1989, same DALLAS date code!), but with
unknown powering history.

Additionally, a typical 10 years of lifetime is given also for those
batteries.

Therefore, in practise there will be no pronounced difference between
powered / unpowered state.
On the other hand, DALLAS implemented an electronic seal, so that the
RAM inside the package is initially powered only after first power up.
But there's no parameter in the datasheet, specifying data retention
according to date code or to initial power up.


The waste of energy just to extend the batteries lifetime, does not pay 
off.

On the contrary, the MTBF time of the instrument will be consumed, the
display will get bad, and here in Germany, this energy consumption would
cost a fortune (meanwhile: 25+ Cents / kWh, crazy).


Yes, as long the instrument is powered, the CAL RAM will not lose its
content.. but what about unexpected power outages?


If you save the CAL RAM and repogram a fresh one after failure, there's
no need to send it to agilent.


No, not any RAM error needs recalibration.
Those error messages are not documented.

So I've scanned the text fragments in the firmware file:

RAM TEST 1
RAM TEST 2

probably refer to either to the configuration RAMs (2x32kB), andthe CAL
RAM (8kB).

Eror messages are:
NONVOLATILE RAM HiGH /LOW
CAL RAM FAILURE

and known ones from other users:

RAM TEST 1 HIGH / LOW

So I assume, that a real failure of the cal constants only apply on
message: CAL RAM FAILURE and perhaps RAM TEST 2 , as RAM TEST 1
should refer to the configuration RAMs only, HIGH to the high byte RAM,
LOW to the low byte RAM.

Errors of the cal RAM will manifest in additional ACAL or CAL failures.


Frank
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Re: [volt-nuts] Fluke 5100B Calibratorþ Repair Help

[Tom Miller]

Hi Dave,

It looks like these are just 68 volt GE MOVs.

MFR Code is 09214 - GE
Fluke Part  460394
GE part V68MA3A

It limits the voltage from the guard circuit to chassis ground. The unit 
limit is 20 V pp from the front panel.


Should not be too critical.

Regards,
Tom




- Original Message - 
From: David Smith w...@msn.com

To: volt-nuts@febo.com
Sent: Thursday, March 13, 2014 12:34 PM
Subject: [volt-nuts] Fluke 5100B Calibratorþ Repair Help



I need some help with repairing a Fluke 5100B Calibrator.
The capacitor support bracket fell into the power supply module and 
vaporized both varistors, RV1 and RV2. A call to Fluke tells me they no 
longer can supply these MOV's. According to the manual's parts list these 
varistors are in-house parts by Fluke. I have no way of determining a 
substitute part. Is there anyone that can help me identify what could be a 
useful replacement?

Thanks,
Dave - W6TE
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Re: [volt-nuts] A Fluke 732A: Return it or keep it?

[Tom Miller]

Some laptop batteries are not allowed. Spares have some limits also. Better 
check because TSA will take them from you.



 Lithium-ion batteries (a.k.a.: rechargeable lithium, lithium polymer, 
LIPO, secondary lithium). Passengers may carry all


consumer-sized lithium-ion batteries (no more than 8 grams of equivalent 
lithium content or 100 watt hours per battery). This


size covers AA, AAA, cell phone, PDA, camera, camcorder, handheld game, 
tablet, and standard laptop computer batteries.


The watt hours (Wh) rating is marked on newer lithium ion batteries and is 
explained in #3 below.


Passengers can also bring two (2) larger lithium-ion batteries (more than 8 
less than 25 grams of equivalent lithium content per


battery or about 100-300 watt hours per battery) in their carry-on. This 
size covers the largest aftermarket extended-life laptop


batteries and most lithium-ion batteries for professional-grade audio/visual 
equipment. Most lithium-ion batteries are below


this size.









- Original Message - 
From: Chuck Harris cfhar...@erols.com

To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Saturday, March 08, 2014 4:36 PM
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?



Surely that isn't true... otherwise laptop computers and cell phones
wouldn't be allowed on board passenger aircraft.  A laptop computer's
battery would greatly exceed the power in the original 732A battery
pack.

-Chuck Harris

Tom Miller wrote:
If you change to Li-Ion, you give up the ability to ship by air or at 
least carry it

in any passenger aircraft.

You might look at the Li-Ion motorcycle batteries. They are designed to 
charge from a
normal Pb-Ac system. Down side is a pair of them will run ~$600. They are 
 20 AH at

12 volts nominal.

Regards,
Tom


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Re: [volt-nuts] JJA progress report

[Tom Miller]

How about the need for liquid He refrigeration? Will this bargain based JJA 
have a closed loop cooling system?


Sure sounds interesting though.

Tom

- Original Message - 
From: Joe Hobart n...@npgcable.com

To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Sunday, February 16, 2014 2:54 PM
Subject: Re: [volt-nuts] JJA progress report



Thanks to the DOD and radio waves, accurate frequency is available at most
places on Earth.  SPRTs and more robust Reference PRTs have been available 
for

many years.

Frequency to one part in a thousand million is easy.  Measuring 
temperature to

0.1 degree C is also easy; controlling temperature may not be as easy.

What are the frequency, temperature, and other requirements for the
inexpensive JVS systems NIST has been developing?

How many similar JVS/JJA units does a major test equipment company like 
Agilent

or Fluke have at any one location?

Joe


On 2/16/2014 12:00 PM, Chuck Harris wrote:

There are a host of things that will cause a JJA to be
off voltage... not the least of which is temperature and
frequency.

Absent other standards to compare with your JJA, you are
really operating in the blind.

The only major advantage to the JJA, and the reason it is
given primary standard status, is it relates voltage, to
frequency.  If the pumping frequency is offset for some
reason, the voltage will be wrong by a similar amount.

Do you imagine that NIST uses only one JJA to hold the
nation's standard volt?

-Chuck Harris

Tom Knox wrote:
The physics of a properly run JJA will always produce the same result so 
you do
not need additional units for comparison. That is the point of a world 
wide

quantum voltage standard defined as K
J-90   = 483 597.9 GHz/V . Just 
has the
Hyperfine Transition of Cesium at about 9.192631770GHz is used to define 
the
second. What is neat about the work NIST has done recently is that it 
has
automated the System for ease of use and reduced the price to the point 
that it
should see much wider use in day to day metrology.  Having your Agilent 
3458A
calibrated on a JJA may not yield much difference over a Fluke 5730A 
cal, but

once
the meter has been run a few years characterizing the A to D converter 
and 10VAC

range would only need to be done once and could substantially improve
performance.
I personally think that the face of calibration will change in coming 
years,
rather then simple time based cal periods, instruments will contain 
complex
environmental sensor packages that will constantly monitor the 
instruments
environment . S o calibration will be based more on the instruments 
exposure to
extreme conditions then simple time. I bet the act of shipping has more 
effect on

cal then years sitting in a lab. So if for example a 3458A was put in an
environmental chamber on a shaker table I am sure we find that up to a 
certain
point enviromental conditions would have little effect on cal but at 
some point
would have a major effect. Once documented the cals would be based more 
on
environmental exposure. In addition I am sure some environmental effects 
on cal
are repeatable and could be documented so if monitored they could be 
compensated
for extending time between cals. So in the future you would see your 
instrument
display environment conditions exceeded cal require, with perhaps 
even a
display of currently instrument uncertainty.  This could change the face 
of

calibration and become a multi-billion dollar industry.

Thomas Knox




Date: Sun, 16 Feb 2014 07:06:18 -0700 From: n...@npgcable.com To:
volt-nuts@febo.com Subject: Re: [volt-nuts] JJA progress report


If Earth is subjected to a GRB strong enough to damage ground based
electronics, we are all going to have much more urgent problems than 
wondering
if a JVS is operating properly.  Same for an EMP.  Lightning, however, 
might

pose a more localized and serious threat.

Part of your training as an expert operator will include techniques to 
dissuade

various critters from considering the JVS for their burial ceremonies.

Carrying your best zener reference to the nearest facility with another 
JVS
would be less expensive than buying and operating a second or third 
system.


Joe


On 2/16/2014 12:58 AM, cheater00 . wrote:
How do you know the primary standard is not off? That is, how do you 
know it's
still primary? Maybe a gamma ray burst from a supernova damaged some 
of the
machinery inside, or a colony of crazy ants crawled in and died 
inside.


D.

On Sat, Feb 15, 2014 at 10:10 PM, Joe Hobart n...@npgcable.com 
wrote:


These devices are primary standards; you don't need three; you 
probably
don't even need two.  If certain conditions are met, conditions you 
can

check/verify, they will accurately generate the desired voltages.

What you will probably want are at least three good zener type 
voltage
standards and a constant temperature environment.  The three will 
serve as a
day to day 

Re: [volt-nuts] JJA progress report

[Tom Miller]

Can we get a group buy?


- Original Message - 
From: Tom Knox act...@hotmail.com

To: volt-nuts@febo.com
Sent: Friday, February 14, 2014 12:50 PM
Subject: [volt-nuts] JJA progress report


More progress has been made toward a plug and play Programmable Josephson 
Voltage Standard then I was aware of in some previous posts. Shortly NIST 
will begin selling Programmable Josephson Voltage Standard AC - DC 
standards that will have software to automatically calibrate (With-in the 
Arrays limit) products like the Agilent 3458A. This will include features 
like detailed characterizing the A-D converter linearity.  The price will 
be about 300K. So we are a great deal closer then I thought to 
Programmable Josephson Voltage Standard for every Volt-Nut.


Thomas Knox



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Re: [volt-nuts] (no subject)

[Tom Miller]

Can you get a service/calibration manual for it?

I just sent my HP3457A out for calibration. $150

Tom

- Original Message - 
From: Joseph Gray jg...@zianet.com

To: volt-nuts@febo.com
Sent: Sunday, July 28, 2013 5:05 PM
Subject: [volt-nuts] (no subject)



I just had a friend buy this for me (I don't have an ebay account). I hope
I didn't make a mistake.

http://www.ebay.com/itm/Electronic-Development-Corporation-EDC-VS330-VOLTAGE-STANDARD-/161069656213?nma=truesi=PiGtcBMSdSOxgbm9DhiZ6iLo1GQ%253Dorig_cvip=truert=nc_trksid=p2047675.l2557

Of course, once I have it, it's the chicken and egg problem. The best I
have to check it against is an HP 3478A that was last calibrated an 
unknown

number of years ago. It has a little round sticker over the CAL switch on
the front, but no dated calibration label that I can see. It came from a
repair facility that closed a few years ago.

Actually, the reason I was tempted to buy the VS330 was because I think 
the

3478A is off a bit. A while back, I built a simple 5V reference with a
MAX6350. The 3478A read high. I took the reference to work and the best
Fluke handheld we have was dead on (I don't remember the model right now).

I made the measurement again last night and the 3478A reads 5.0026 V, with
the last digit fluctuating. Room temperature was 26 C.

I guess obsessing about these things has brought me here to the Volt Nuts.
I have been on Time Nuts for several years.

Joe Gray
W5JG
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Re: [volt-nuts] (no subject)

[Tom Miller]

At least the subject is correct :)


- Original Message - 
From: Orin Eman orin.e...@gmail.com

To: Discussion of precise voltage measurement volt-nuts@febo.com
Sent: Sunday, July 28, 2013 10:34 PM
Subject: Re: [volt-nuts] (no subject)



Three empty messages!

Cat sitting on keyboard?


On Sun, Jul 28, 2013 at 7:31 PM, wb6bnq wb6...@cox.net wrote:



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