Re: [volt-nuts] Calibration and Certification - Trust and detail

[Robert Atkinson]

Hi ,
Newer does not mean better. It's not "nuts" level, but my Fluke 8060A 4.5 digit 
handhelds are more accurate and stable than my newer 89 IV. However most 
"engineers" would pick up the 89.
I agree with Dave on UK " engineers" For many years I've been a member of the 
very few groups of engineer in the UK who need a licence to do their job - 
aircraft, but even that has been diluted since EU regulations came into force. 
I'm also a Chartered Engineer similar to PE in the USA. As I understand it most 
US States require you to be a PE before you can do business as an "Engineer". 
In the UK it's a bloke with an oily rag and big hammer :-(
 
Robert CEng MRAeS G8RPI 



From: Orin Eman 
To: Discussion of precise voltage measurement  
Sent: Tuesday, 13 August 2013, 5:56
Subject: Re: [volt-nuts] Calibration and Certification - Trust and detail


On Sun, Aug 11, 2013 at 3:36 PM, Orin Eman  wrote:

>
> I should go get the kelvin clips out and compare the 3456A against the
> '61A on some 10k precision wirewound resistors I have.
>


I did.  The resistors are MR102 series 0.01% 1/8W wirewound:

34461A: 10.000 82 +/- 0.000 90
3456A: 10.000 98 +/- 0.000 58

Using 90 day specs for the 61A and 90 day plus 0.0004% per month for the
56A.  Yes, the 3456A resistance specs are better than the shiny new 34461A.

I also compared the DC voltage ranges from 0.1 to 1000V and other than on
the 1KV range, results were within 10ppm.  Still, given the 3456A spec
sheet says add .12(input voltage/1000)^2 % on the 1KV range, I can't
complain; I got 999.984 on the 61A and 1000.062 on the 56A.  I'm pretty
sure that the superscript 2 in the spec meant squared, not that it matters
for 1000/1000.

Now has anyone calibrated a Fluke 343A?  The instructions in the manual are
entertaining.  They tell you to adjust the 1000V range to +/- 1mV, but the
post calibration check says that a freshly calibrated unit should be +/-
100uV at the 1000V setting.

Orin.
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Re: [volt-nuts] HP 3457A

[John Phillips]

This all comes down to accreditation/Licensing. There are a lot of
situations that a co. rep is enough. Accreditation/Licensing costs money.
If you require them you will have to pay. Traceability can be had without
accreditation. Calibration has been around much longer that accreditation.
It all come down to where the interment is to be used and what controls the
calibration requirement. A lot of work can be done without calibration. If
the work is not critical calibration is not required even if it is
desirable.



On Mon, Aug 12, 2013 at 6:47 PM, Dr. David Kirkby wrote:

> On 12 August 2013 17:43, Mike S  wrote:
> > On 8/12/2013 12:21 PM, Charles Steinmetz wrote:
> >>
> >> No, you could not perform ANY traceable calibration with the 3458A
> >> itself, much less with any instrument you had calibrated with the 3458A,
> >> because *you* are not accredited
> >
> >
> > That's simply not true. Some organizations may require a lab to be
> > accredited in order to accept their services, but it is not a
> requirement in
> > order to legitimately claim traceability.
>
> This is the conclusion I had reached. So it would appear to me quite
> easy to legitimately claim traceability to NIST.
>
> Others seem to disagree with this, and talk about accreditation and
> being able to meet original manufacturers specifications. I don't
> actually see this being a requirement myself, but I'm no expert.
>
> Of course, I would never attempt to calibrate a 8.5 digit laboratory
> multi-meter using a 4.5 digit handheld one, but there does not appear
> to be anything to stop me doing that, and furthermore claiming
> tractability to NIST.
>
> It is a bit like the "engineer" in England - anyone can call
> themselves an engineer, irrespective of how incompetent they are. I
> believe that is not so in some other countries.
>
> Dave
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-- 
John Phillips
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Re: [volt-nuts] Calibration and Certification - Trust and detail

[Orin Eman]

On Sun, Aug 11, 2013 at 3:36 PM, Orin Eman  wrote:

>
> I should go get the kelvin clips out and compare the 3456A against the
> '61A on some 10k precision wirewound resistors I have.
>


I did.  The resistors are MR102 series 0.01% 1/8W wirewound:

34461A: 10.000 82 +/- 0.000 90
3456A: 10.000 98 +/- 0.000 58

Using 90 day specs for the 61A and 90 day plus 0.0004% per month for the
56A.  Yes, the 3456A resistance specs are better than the shiny new 34461A.

I also compared the DC voltage ranges from 0.1 to 1000V and other than on
the 1KV range, results were within 10ppm.  Still, given the 3456A spec
sheet says add .12(input voltage/1000)^2 % on the 1KV range, I can't
complain; I got 999.984 on the 61A and 1000.062 on the 56A.  I'm pretty
sure that the superscript 2 in the spec meant squared, not that it matters
for 1000/1000.

Now has anyone calibrated a Fluke 343A?  The instructions in the manual are
entertaining.  They tell you to adjust the 1000V range to +/- 1mV, but the
post calibration check says that a freshly calibrated unit should be +/-
100uV at the 1000V setting.

Orin.
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Re: [volt-nuts] HP 3457A

[Dr. David Kirkby]

On 12 August 2013 17:43, Mike S  wrote:
> On 8/12/2013 12:21 PM, Charles Steinmetz wrote:
>>
>> No, you could not perform ANY traceable calibration with the 3458A
>> itself, much less with any instrument you had calibrated with the 3458A,
>> because *you* are not accredited
>
>
> That's simply not true. Some organizations may require a lab to be
> accredited in order to accept their services, but it is not a requirement in
> order to legitimately claim traceability.

This is the conclusion I had reached. So it would appear to me quite
easy to legitimately claim traceability to NIST.

Others seem to disagree with this, and talk about accreditation and
being able to meet original manufacturers specifications. I don't
actually see this being a requirement myself, but I'm no expert.

Of course, I would never attempt to calibrate a 8.5 digit laboratory
multi-meter using a 4.5 digit handheld one, but there does not appear
to be anything to stop me doing that, and furthermore claiming
tractability to NIST.

It is a bit like the "engineer" in England - anyone can call
themselves an engineer, irrespective of how incompetent they are. I
believe that is not so in some other countries.

Dave
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Re: [volt-nuts] HP 3457A

[MARVIN]

For USA buyers, Barrytech tracks eBay sold prices for > 10 years and I find his 
estimates accurate. Despite the site's lack of updates, it compares well to the 
3+ years I've tracked weekly prices on various Tek and HP models. I've used his 
low price estimate as a guide to model's I don't track and had much success. 

http://www.barrytech.com/hewlett-packard/meters_digital/hp3457a.html 

That said, here's my gestalt of prices; you can decide which model is best. 

3455a: $50-100 
3456a $50-100 
3457a $180-300 
34401a $300-700 [ new its $1000]. 

The 34401a range is particularly wide because its still in production and in 
catalog, although its days are numbered. 

The 3455a does not use the dual slope ADC patented by HP back when, but is now 
commonplace in many DMMs, so its the least accurate of DMM in the listing. 

I would not pay a premium for a "NIST traceable" certificate of an eBay sold 
device. A good cal is a trust-me event, so impeccable credentials and adherence 
from the calibrator are needed. Properly done, its easily > 50-100% of low end 
prices. 




- Original Message -

From: "Joseph Gray"  
To: "Discussion of precise voltage measurement"  
Sent: Sunday, August 11, 2013 2:00:29 PM 
Subject: Re: [volt-nuts] HP 3457A 

Would a 34401A be a better choice, over a 3457A for a budding volt-nut? It 
is newer and smaller, and the ebay pricing is similar. Would having that 
extra digit via GPIB on the 3457A really be of any practical value? 

Joe Gray 
W5JG 


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Re: [volt-nuts] HP 3457A

[Mike S]

On 8/12/2013 2:23 PM, John Phillips wrote:

A calibration indicates that the unit under test is withing manufactures
specification. The equipment and procedure used has to be "good enough"
(bad words in a cal lab) to have a high probability (nothing is 100%) of
insuring the calibration documentation is valid. Things can  can be a
little looser if you are calibrating a 1% meter with a 10 ppm meter but it
does not work the other way around.


You can calibrate either way. You can't however, calibrate the 10 ppm 
meter so it's in spec using a 1% meter. That's different. Calibration 
merely means that it's documented how close it is to a reference, such 
as NIST, not that it's within the manufacturer's spec. The 10 ppm meter 
would end up with a 1%+ calibration - precise but not accurate. Not 
particularly useful, but valid. A good cal lab would do a calibration to 
specification, where the uncertainties place the 10 ppm meter within spec.


As I cited and someone else already quoted, calibration is the "property 
of a measurement result whereby the result can be related to a reference 
through a documented unbroken chain of calibrations, each
contributing to the measurement uncertainty." Nothing to do with making 
a device meet its specifications.


That's why an eBay seller can claim they'll do a "calibration traceable 
to NIST," because they're not claiming any particular accuracy. It's 
really not worth anything, unless they give specific uncertainties or 
claim calibration to manufacturer's specification.

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Re: [volt-nuts] HP 3457A

[John Phillips]

A calibration indicates that the unit under test is withing manufactures
specification. The equipment and procedure used has to be "good enough"
(bad words in a cal lab) to have a high probability (nothing is 100%) of
insuring the calibration documentation is valid. Things can  can be a
little looser if you are calibrating a 1% meter with a 10 ppm meter but it
does not work the other way around.



On Mon, Aug 12, 2013 at 9:43 AM, Mike S  wrote:

> On 8/12/2013 12:21 PM, Charles Steinmetz wrote:
>
>> No, you could not perform ANY traceable calibration with the 3458A
>> itself, much less with any instrument you had calibrated with the 3458A,
>> because *you* are not accredited
>>
>
> That's simply not true. Some organizations may require a lab to be
> accredited in order to accept their services, but it is not a requirement
> in order to legitimately claim traceability.
>
> The NIST Traceability Policy is found here:
> http://www.nist.gov/**traceability/nist_**traceability_policy_external.**
> cfm
>
>
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> and follow the instructions there.
>



-- 
John Phillips
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Re: [volt-nuts] HP 3457A

[Robert Atkinson]

Hi Charles,
I've never heard of "leagal Tracability" in connection with calibration. Nist 
say "NIST adopts for its own use and recommends for use by others the 
definition of metrological traceability2 provided in the most recent version of 
the International Vocabulary of Metrology: "property of a measurement result 
whereby the result can be related to a reference through a documented unbroken 
chain of calibrations, each 
contributing to the measurement uncertanty" (International Vocabulary of 
Metrology - Basic and General concepts and Associated Terms (VIM)"
No mention of accreditation there. Competence may be implied but it's not a 
requirement, Accreditation is typically a contractural obligation. I'm in the 
UK but do a lot of work to North American legislation. I've been quality 
manager of an FAA approved instrument shop. The biggest drivers for 
accreditation are quality systems like ISO9000 and AS9100. but they don't 
automatically improve quality. 
Companies overcalibrate lots of equipment. A good example is bench power 
supplies. An indication only sticker and use of a DMM when it's critical is all 
that is required.
A similar misconeption is the requirement for portable appliance testing (PAT) 
in the UK. There is no requirement for testing, just an obligation to ensure 
equipment is safe. Having a test program does not reduce liability in the case 
of an accident. It's the insurance companies who want testing. It used to be a 
similar situation with UL approval in the USA, but that is changing as 
individual States bring in legislation.


Robert G8RPI.




 From: Charles Steinmetz 
To: Discussion of precise voltage measurement  
Sent: Monday, 12 August 2013, 18:34
Subject: Re: [volt-nuts] HP 3457A
 

Robert wrote:

>I have to disagree on one point, You CAN do a TRACABLE calibration 
>without any approval. What you can't do is  ACCREDITED  Calibration.

Things may be different in the UK (after all, "traceability" is short 
for "legal traceability," and the law of legal metrology may be 
different there), but in the US one of the necessary criteria for 
traceability is "demonstrated competence."  There may be a 
philosophical question whether "competence" can be "demonstrated" in 
some manner other than by accreditation, but there is no practical 
question.  Universally (in the US), this is done by becoming 
accredited to the relevant ISO/IEC standard.

Best regards,

Charles



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Re: [volt-nuts] Solartron / Schlumberger 7150, 7150 plus, 7151

[Robert Atkinson]

Hi Jan,
The component that fails in the Solartrons is a filter capacitor in the mains 
inlet. It's an easy fix. Both the 7150 and the plus will read to 61/2 digits 
but the accuracy is is only quoted to 51/2 digits. The plus has a slightly 
better short term stability but the long term is hard to compare as the 7150 is 
quoted over two years and the Plus for one. Good "bang for the Buck" certainly 
here in the UK where hundreds of military surplus ones are available. Still 
have one but it's been replaced as my everyday bench meter by a Keithley 197 
that I picked up at a local rally for a tenner. Don't think that the seller 
knew that the "ERROR" display indicated that you had AC and Ohms selected at 
the same time :-)


Robert G8RPI.




 From: Jan Fredriksson 
To: volt-nuts@febo.com 
Sent: Monday, 12 August 2013, 16:44
Subject: [volt-nuts] Solartron / Schlumberger 7150, 7150 plus, 7151
 

Throwing in my 2C on 5-1/2 - 6-1/2 digit DMMs on a budget

I have had a few Solartron / Schlumberger 7150, 7150 plus, 7151, 5-1/2
6-1/2 digit DMMs

Pro:
- available at very good prices on the net (especially in the UK?). I think
I paid around £50 for them. Except one bought brand new 20+ years ago.
- stability has been very good.
- Fairly compact boxes
- usually have GPIB
- schematics are available on the web

The 7150 are 5.5 digit, while 7150 plus and 7151 are 6.5 digit.

Con:
- There is a bad mains component causing smoke / shorts with age. Smokes
and smells badly so it is easy to find :-) I do not remember details but
gave a 7150 away when it smoked. The guy who got it fixed it.
- 2A max DC current range
- 2kohm min resistance range.
- Terminals are banana jacks without binding posts

A 7151 attached under a shelf over the workbench is my daily DMM. It is
turned on 24/7

JF
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Re: [volt-nuts] HP 3457A

[Poul-Henning Kamp]

In message <20130812213441.yeqem...@smtp16.mail.yandex.net>, Charles Steinmetz 
writes:

>>I have to disagree on one point, You CAN do a TRACABLE calibration 
>>without any approval. What you can't do is  ACCREDITED  Calibration.

Agreed, those are two very different things.

Tracability is about the instruments performance.

Accreditation (and certification) is a legal framework of trust
and responsibility, and it's waay too expensive for the
benefits you get.

Many larger companies could buy their own Josephson standard for
the money they waste on certificates and fancy stamps on their
multimeters every year.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [volt-nuts] HP 3457A

[Charles Steinmetz]

Robert wrote:

I have to disagree on one point, You CAN do a TRACABLE calibration 
without any approval. What you can't do is  ACCREDITED  Calibration.


Things may be different in the UK (after all, "traceability" is short 
for "legal traceability," and the law of legal metrology may be 
different there), but in the US one of the necessary criteria for 
traceability is "demonstrated competence."  There may be a 
philosophical question whether "competence" can be "demonstrated" in 
some manner other than by accreditation, but there is no practical 
question.  Universally (in the US), this is done by becoming 
accredited to the relevant ISO/IEC standard.


Best regards,

Charles



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Re: [volt-nuts] HP 3457A

[Mike S]

On 8/12/2013 12:21 PM, Charles Steinmetz wrote:

No, you could not perform ANY traceable calibration with the 3458A
itself, much less with any instrument you had calibrated with the 3458A,
because *you* are not accredited


That's simply not true. Some organizations may require a lab to be 
accredited in order to accept their services, but it is not a 
requirement in order to legitimately claim traceability.


The NIST Traceability Policy is found here:
http://www.nist.gov/traceability/nist_traceability_policy_external.cfm

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Re: [volt-nuts] HP 3457A

[Robert Atkinson]

Hi Charles,
I have to disagree on one point, You CAN do a TRACABLE calibration without any 
approval. What you can't do is  ACCREDITED  Calibration. Many labs are 
accredited but also offer un-accredited, tracable calibration at lower cost. An 
example is that production test equipment could be tracable but qualification 
test accredited. Accredition is normally driven by legislation or 
self-regenerating "quality" systems.
Of course if you cal a 4.5 digit meter against a tracable standard, the highest 
level you could reasonably sub-calibrate would be 3.5 digit or possibly 3200 
count. This assumes the 4.5 digit has suitable accuracy and stability 
specifications, just because it has more digits does not mean it's more 
accurate ;-)
Somethings don't need to be tracable, a Fluke 720 K-V divider or Caesium 
frequency standard spring to mind.

Robert G8RPI





 From: Charles Steinmetz 
To: Discussion of precise voltage measurement  
Sent: Monday, 12 August 2013, 17:21
Subject: Re: [volt-nuts] HP 3457A
 

Dave wrote:

>I see a lot of sellers selling things on ebay which are NIST tracable,
>but I wonder what this means.
>
>Let's asume I borrow a 3458A 8.5 digit DVM which has a valid (i.e.
>non- goldenrubi ) NIST tracable calibration, and use the 3458A to
>calibrate my 4.5 digit handheld DVM. If I work out all the
>uncertainties, could I perform a NIST traceable calibration on a 6.5,
>7.5 or even 8.5 digit meter using my handheld DVM?

No, you could not perform ANY traceable calibration with the 3458A 
itself, much less with any instrument you had calibrated with the 
3458A, because *you* are not accredited (i.e., your laboratory 
procedures are not reviewed and audited by a competent third-party to 
establish their reliability and, therefore, to create the link of 
traceability between your USE of the traceable 3458A and a primary 
voltage standard).  Thus, the chain of traceability is broken at your 
USE of the 3458A.  You would have a tool with a traceable calibration 
(the 3458A), but you could not perform traceable calibrations with it 
unless you obtained accrditation for your home lab.

Equipment dealers and even some so-called "calibration labs" ignore 
this fact and act as if using the traceable DMM to calibrate another 
instrument can result in a traceable calibration, notwithstanding the 
fact that the person/lab doing that calibration is not accredited 
(this appears to be universal on ebay, but is common among used 
equipment dealers everywhere).  That is simply not 
true.  Traceability exists *only if* there is an unbroken chain of 
*accredited* measurements between the calibrated instrument and a 
primary standard.

Calibration is one thing.  Traceable calibration is another thing 
entirely, and virtually nothing you find on ebay is traceably 
calibrated regardless of what the seller says (or thinks).

Best regards,

Charles


ps.  For most products, Agilent uses different equipment to do the 
different levels of calibrations.  (I cannot speak specifically to 
their VNA calibrations.)


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Re: [volt-nuts] Sn10Pb90

[Volker Esper]

Sorry, Joe, if my question was mistakable. I wanted to know your 
application. Maybe I'd recommend not using a special solder alloy rather 
than going the long way of aquiring it.


I give you an example: When fixing a 6.5 digit DMM (HP34401A) I wasn't 
sure if I might use a special alloy to solder the pins of an input 
relay. In the end I did not. Comparing this fixed unit to a second one 
in several automated 24 hours tests with varying room temperatures, 
there seem to be no measurable differences between the two. So in this 
case it appears to be of no great importance using a special solder.


Enthough the thermoelectric voltages at these pins are not negligible 
and therefore have to be considered, other effects obviously are of much 
more effect. So, as I mentioned, using a special soldering alloy drops 
in the priority list.


Now, that I'm curious, please let us know, what you are using the solder 
for.


Volker
DF9PL


Am 12.08.2013 15:06, schrieb Joseph Gray:

As I asked in my original message, I'm trying to find out where I can buy a
small quantity of rosin-core 10/90 (tin/lead) solder. I don't want to buy
it in bar form from China.

Joe Gray
W5JG



On Mon, Aug 12, 2013 at 3:17 AM, Volker Esper  wrote:

   

sorry, spelling mistake:
"What do you _want_ it for?"

Remember, those solder alloys are optimized for a specific alloy
combination only, e.g. Cu-Cu.

Volker


Am 12.08.2013 10:39, schrieb Volker Esper:


 

Hi Joe,

What are you looking for, Cadmium-Solder, or Sn10Pb90, which is
Stannum/Plumbum-only?

And what do you what it for? In (very high) precision applications there
are so many issues to consider that the solder doesn't appear to be at a
high priority...

Volker


Am 12.08.2013 00:38, schrieb Joseph Gray:

   

Reading through the archives, I saw that there was some discussion about
a
safer alternative to cadmium-based solder. The low tin, high lead alloy
was
recommended as a good low-thermal EMF substitute. However, I did not see
any recommendations on where to buy some of this.

I just did some searching and all I come up with is bar solder, mostly
from
China. Where can I buy a small quantity of rosin-core 10/90 solder?
Mouser,
which is my preferred vendor certainly didn't list any. I would think
that
even 1/2  pound would last me a lifetime.

Joe Gray
W5JG
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Re: [volt-nuts] Calibration Device

[Robert Atkinson]

The Geller Labs SVR-T is another good option. 
http://www.gellerlabs.com/Voltage%20References.htm


Robert G8RPI.




 From: J. Forster 
To: Discussion of precise voltage measurement  
Sent: Monday, 12 August 2013, 15:11
Subject: [volt-nuts] Calibration  Device
 

David mentioned this:

http://www.ebay.com/itm/281149723636

What do people think of the device? Is it available direct from the
seller, and, if so, does anyone have the contact address?

Thanks,

-John

===

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Re: [volt-nuts] Calibration Device

[zbigniew169]

I don think it would be useful for serius purposes.


2013/8/12 J. Forster 

> David mentioned this:
>
> http://www.ebay.com/itm/281149723636
>
> What do people think of the device? Is it available direct from the
> seller, and, if so, does anyone have the contact address?
>
> Thanks,
>
> -John
>
> ===
>
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-- 
Zbyszek
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Re: [volt-nuts] HP 3457A

[Charles Steinmetz]

Dave wrote:


I see a lot of sellers selling things on ebay which are NIST tracable,
but I wonder what this means.

Let's asume I borrow a 3458A 8.5 digit DVM which has a valid (i.e.
non- goldenrubi ) NIST tracable calibration, and use the 3458A to
calibrate my 4.5 digit handheld DVM. If I work out all the
uncertainties, could I perform a NIST traceable calibration on a 6.5,
7.5 or even 8.5 digit meter using my handheld DVM?


No, you could not perform ANY traceable calibration with the 3458A 
itself, much less with any instrument you had calibrated with the 
3458A, because *you* are not accredited (i.e., your laboratory 
procedures are not reviewed and audited by a competent third-party to 
establish their reliability and, therefore, to create the link of 
traceability between your USE of the traceable 3458A and a primary 
voltage standard).  Thus, the chain of traceability is broken at your 
USE of the 3458A.  You would have a tool with a traceable calibration 
(the 3458A), but you could not perform traceable calibrations with it 
unless you obtained accrditation for your home lab.


Equipment dealers and even some so-called "calibration labs" ignore 
this fact and act as if using the traceable DMM to calibrate another 
instrument can result in a traceable calibration, notwithstanding the 
fact that the person/lab doing that calibration is not accredited 
(this appears to be universal on ebay, but is common among used 
equipment dealers everywhere).  That is simply not 
true.  Traceability exists *only if* there is an unbroken chain of 
*accredited* measurements between the calibrated instrument and a 
primary standard.


Calibration is one thing.  Traceable calibration is another thing 
entirely, and virtually nothing you find on ebay is traceably 
calibrated regardless of what the seller says (or thinks).


Best regards,

Charles


ps.  For most products, Agilent uses different equipment to do the 
different levels of calibrations.  (I cannot speak specifically to 
their VNA calibrations.)



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Re: [volt-nuts] Calibration Device

[J. Forster]

My main interest is as a 'sanity check'. I use DMMs for engineering purposes.

Shields up:

IMO, there are very few applications, other than fundamental physics
research, that really NEED 5,6,7, or 8+ digits.

I would no more use a multi digit DVM to do what can be done with a
differential voltmeter than use a carrier phase tracking GPS to measure
for a living room carpet.

Shields down.

-John





> John wrote:
>
>>David mentioned this:
>>*   *   *
>>What do people think of the device?
>
> What are you trying to accomplish?  As I posted previously:
>
>>Let's assume that it is still working exactly the same as it was
>>when it was calibrated.  The calibration values are recorded to
>>4-1/2 digits.  So the uncertainty is greater than the two LSDs of a
>>3457A.  Of course, it is almost certainly not working exactly the
>>same as it was when it was calibrated, [so its last digit is going
>>to be uncertain,] which is going to put at least the third LSD of a
>>3457A in question.  So it is good enough for a 3457A only if one is
>>content with a 3-1/2 digit verification on a 6-1/2 digit instrument.
>
> You should be able to rely on it to verify instruments to 3-1/2
> digits.  Beyond that, you would need something with a smaller uncertainty.
>
> Best regards,
>
> Charles
>
>
>
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Re: [volt-nuts] Calibration Device

[Charles Steinmetz]

John wrote:


David mentioned this:
   *   *   *
What do people think of the device?


What are you trying to accomplish?  As I posted previously:

Let's assume that it is still working exactly the same as it was 
when it was calibrated.  The calibration values are recorded to 
4-1/2 digits.  So the uncertainty is greater than the two LSDs of a 
3457A.  Of course, it is almost certainly not working exactly the 
same as it was when it was calibrated, [so its last digit is going 
to be uncertain,] which is going to put at least the third LSD of a 
3457A in question.  So it is good enough for a 3457A only if one is 
content with a 3-1/2 digit verification on a 6-1/2 digit instrument.


You should be able to rely on it to verify instruments to 3-1/2 
digits.  Beyond that, you would need something with a smaller uncertainty.


Best regards,

Charles



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[volt-nuts] Solartron / Schlumberger 7150, 7150 plus, 7151

[Jan Fredriksson]

Throwing in my 2C on 5-1/2 - 6-1/2 digit DMMs on a budget

I have had a few Solartron / Schlumberger 7150, 7150 plus, 7151, 5-1/2
6-1/2 digit DMMs

Pro:
- available at very good prices on the net (especially in the UK?). I think
I paid around £50 for them. Except one bought brand new 20+ years ago.
- stability has been very good.
- Fairly compact boxes
- usually have GPIB
- schematics are available on the web

The 7150 are 5.5 digit, while 7150 plus and 7151 are 6.5 digit.

Con:
- There is a bad mains component causing smoke / shorts with age. Smokes
and smells badly so it is easy to find :-) I do not remember details but
gave a 7150 away when it smoked. The guy who got it fixed it.
- 2A max DC current range
- 2kohm min resistance range.
- Terminals are banana jacks without binding posts

A 7151 attached under a shelf over the workbench is my daily DMM. It is
turned on 24/7

JF
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Re: [volt-nuts] Calibration Device

[Gordon Batey]

John:

I bought one that looks just like that from:

http://www.voltagestandard.com/

It looks and works just fine as far as I can determine.

73 Gordon WA4FJC




Date: Mon, 12 Aug 2013 07:11:36 -0700 (PDT)
From: "J. Forster" 
To: "Discussion of precise voltage measurement" 
Subject: [volt-nuts] Calibration  Device
Message-ID:
<37087.12.226.214.5.1376316696.squir...@popaccts.quikus.com>
Content-Type: text/plain;charset=iso-8859-1

David mentioned this:

http://www.ebay.com/itm/281149723636

What do people think of the device? Is it available direct from the
seller, and, if so, does anyone have the contact address?

Thanks,

-John




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Re: [volt-nuts] HP 3457A

[Dr. David Kirkby]

On 11 August 2013 22:34, Charles Steinmetz  wrote:
> Orin wrote:

>> BTW, they don't list any accreditation on the certificate.
>
>
> As I suspected.  So it is vanishingly unlikely that they do traceable
> calibrations, contrary to their claim.

I see a lot of sellers selling things on ebay which are NIST tracable,
but I wonder what this means.

Let's asume I borrow a 3458A 8.5 digit DVM which has a valid (i.e.
non- goldenrubi ) NIST tracable calibration, and use the 3458A to
calibrate my 4.5 digit handheld DVM. If I work out all the
uncertainties, could I perform a NIST traceable calibration on a 6.5,
7.5 or even 8.5 digit meter using my handheld DVM? Of course, I'm not
suggesting for one minite it is reasonable to calibrate a high end DVM
with a handheld one, but could such a calibration still be NIST
traceable? It would have not a hope in hells chance of being able to
determine if a 6.5 digit DVM is in spec, but does that matter if all
the customer wanted was a NIST traceable calibration?

My VNA is going off to Agilent this week for cal. I'm just having an
Agilent calibration

https://service.home.agilent.com/infoline/public/product-service.aspx?pn=8720D&lc=eng&cc=GB

not an acredited calibration. I know, from discussions I have had with
Agilent staff, it will be the same test equipment calibrating it,
using the same automated procedures, so I don't want to pay 50% extra
for acreditation.

I trust Agilent can properly calibrate their own product.  At the end
of the day a lot of this is about trust.

Dave
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Re: [volt-nuts] Calibration Device

[GandalfG8]

Their web site is.
 
http://www.voltagestandard.com/
 
I bough their VREFR-01 a few years ago when they were trading as Malone  
Electronics.
 
Regards
 
Nigel
GM8PZR
 
 
In a message dated 12/08/2013 15:17:35 GMT Daylight Time, j...@quikus.com  
writes:

David  mentioned this:

http://www.ebay.com/itm/281149723636

What do  people think of the device? Is it available direct from the
seller, and, if  so, does anyone have the contact  address?

Thanks,

-John

===

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[volt-nuts] Calibration Device

[J. Forster]

David mentioned this:

http://www.ebay.com/itm/281149723636

What do people think of the device? Is it available direct from the
seller, and, if so, does anyone have the contact address?

Thanks,

-John

===

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Re: [volt-nuts] Sn10Pb90

[Joseph Gray]

As I asked in my original message, I'm trying to find out where I can buy a
small quantity of rosin-core 10/90 (tin/lead) solder. I don't want to buy
it in bar form from China.

Joe Gray
W5JG



On Mon, Aug 12, 2013 at 3:17 AM, Volker Esper  wrote:

>
> sorry, spelling mistake:
> "What do you _want_ it for?"
>
> Remember, those solder alloys are optimized for a specific alloy
> combination only, e.g. Cu-Cu.
>
> Volker
>
>
> Am 12.08.2013 10:39, schrieb Volker Esper:
>
>
>> Hi Joe,
>>
>> What are you looking for, Cadmium-Solder, or Sn10Pb90, which is
>> Stannum/Plumbum-only?
>>
>> And what do you what it for? In (very high) precision applications there
>> are so many issues to consider that the solder doesn't appear to be at a
>> high priority...
>>
>> Volker
>>
>>
>> Am 12.08.2013 00:38, schrieb Joseph Gray:
>>
>>> Reading through the archives, I saw that there was some discussion about
>>> a
>>> safer alternative to cadmium-based solder. The low tin, high lead alloy
>>> was
>>> recommended as a good low-thermal EMF substitute. However, I did not see
>>> any recommendations on where to buy some of this.
>>>
>>> I just did some searching and all I come up with is bar solder, mostly
>>> from
>>> China. Where can I buy a small quantity of rosin-core 10/90 solder?
>>> Mouser,
>>> which is my preferred vendor certainly didn't list any. I would think
>>> that
>>> even 1/2  pound would last me a lifetime.
>>>
>>> Joe Gray
>>> W5JG
>>> __**_
>>> 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.
>>>
>>>
>>>
>>
>> __**_
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>> mailman/listinfo/volt-nuts
>> and follow the instructions there.
>>
>>
>>
>
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Re: [volt-nuts] HP 3457A

[Robert Atkinson]

Hi Dave,
I find it interesting that goldenrubi uses other dealers websites as sources 
for datasheets in his auctions!
I looked for a laminated HP panel for you but it seems all the one I have are 
the earlier painted and screen printed versions. 
 
Robert G8RPI.



From: Dr. David Kirkby 
To: Discussion of precise voltage measurement  
Sent: Monday, 12 August 2013, 10:44
Subject: Re: [volt-nuts] HP 3457A


On 11 August 2013 05:10, Orin Eman  wrote:
> Well, lets discuss the 3456A I got from goldenrubi, calibrated.  They send
> a calibration certificate which claims that their standards are traceable
> to NIST.  I have no reason to doubt that.  The list of standards used is
> reasonable for a 3456A.

I can't comment on goldenrubi's ability to calibrate a 3457A, but I'm
pretty sure he had a VNA cal kit on eBay which was calibrated. I was
suspicious, but I can't recall the exact details. I can't find the
auction, but I'm 99% sure it was goldenrubi.

I know Orin knows about VNAs, so he at least will understand this. But
even if you don't, it should be clear that you can't calibrate a
device properly using a device of the same specification.

Anyway, goldenrubi has two items on eBay now, both related to vector
network analyzer, neither of which have cal certificates, but I
doubted the accuracy of some comments on those auctions. So I deceided
to use the "ask seller a question" and query things. As I suspected,
he does not have a clue. It should be noted

1) One kit (85032B) has a part missing, which he is clear about.
2) The same kit shows some adapters (which I think are not the correct
models), but the adapters are present. The auction says they are not,
so I query that too.

These two things are not central to the problem.

I also strongly suspect two of these parts in the 85032B are not
original, as they have no HP markings on them at all. I have one of
these kits, and parts clearly have HP markings on them.

1) http://www.ebay.co.uk/itm/14143954is a "TESTED" HP 83032B
typep N calibration kit.
2) http://www.ebay.co.uk/itm/190780743417is a "TESTED" 85053A 26.5
GHz 3.5mm verification kit.

Bear in mind, the manuals for both devices states the equipment to
verify the performance of the kits is not commericially available. Now
goldenrubi tells me he can't calibrate them, but his reasons are
totally wong. He seems to think that he could calibrate the kits if he
had other kits of the same model. This is totally wrong.

I know for a fact the open and short standards should be checked by
mechanical dimensions, not electrical measurements. I have got that
from someone at Agilent who is a specialist in this area. If you look
at papers on the calibration of these things, you will find things
like laser micrometers are used.

=== My 1st message to  goldenrubi 
Dear goldenrubi,

I'm interested in this 85032B. Can you tell me how it was tested? Can
you provide a calibration certificate? The auction states it does not
come with the APC-7 to N adapters, but they are in the picture. Do you
intend removing them? If so,

I'm also interested in the 3.5 mm verification kit you have in another
auction. I'd like to know again how it was tested and whether it is
calibrated.

Dave

- drkirkby
==

He replies, saying he has the network anayzers these kits belong to,
so that is how he tests them!  He says to calibate them he would
need another calibrated kit of the same model. This is total rubbish
as you can buy the kits easy enough (excepting the 85032B is
obsolete), but the manuals make it clear the equipment to verify the
performance is not commerically available.

 goldenrubi  1st reply to me ==
Dear drkirkby,

I do not have the HP - Agilent 85032-60009 Short in this kit. I have
everything else. We have the Network analyzers that these kits belong
too. That is how we test them out. We cannot calibrate them or provide
certificate because we do not have this HP 85032B full kit and we
would need another kit that was calibrated in order to do a one on one
calibration on my kit. You get everything that is in the picture. I
will not remove any item. The 3.5MM verification kit was tested by us.
we have the equipment to test these kits out. WE do not have the
calibration kit to re-cal my kits on a one on one calibration. so we
cannot cal them. NO standards to work with.

- goldenrubi


I seek clarification, to make sure I have understood him correct

== My second message to goldenrubi 
Dear goldenrubi,

OK, I understand the 85032-60009 Short is missing from the 85032B
calibration kit on auction 4143954. If I understand you correctly,
you can't calibrate the 85032B since you don't have another 85032B -
is that correct? Why does your auction for the 85032B say the adapters
are missing, when there are adapters in the picture? What equipment do
you use to test the 85053A 26.5 GHz 3.5mm verification kit in auction
190780743417? Am I cor

Re: [volt-nuts] HP 3457A

[Charles Steinmetz]

Poul-Henning wrote:


People don't understand that "calibrated" doesn't mean that
it shows the right thing, but that you know how wrong it is.


A very pedantic expansion of the above (but then, this is volt-nuts):

"Calibrated" means that you know (i) what your best estimate of the 
actual measured quantity is, based on a given measurement (i.e., the 
predicted "offset" of the calibrated instrument), and (ii) what the 
uncertainty of that estimate is.


Best regards,

Charles



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Re: [volt-nuts] HP 3457A

[Poul-Henning Kamp]

In message 
, "Dr. David Kirkby" writes:

>He seems to think that he could calibrate the kits if he
>had other kits of the same model.

That is a perception I have met more than once:

"I checked it with my other ${type} instrument, and they showed
(pretty much) the same, so it is calibrated."

People don't understand that "calibrated" doesn't mean that it
shows the right thing, but that you know how wrong it is.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [volt-nuts] HP 3457A

[Dr. David Kirkby]

On 11 August 2013 05:10, Orin Eman  wrote:
> Well, lets discuss the 3456A I got from goldenrubi, calibrated.  They send
> a calibration certificate which claims that their standards are traceable
> to NIST.  I have no reason to doubt that.  The list of standards used is
> reasonable for a 3456A.

I can't comment on goldenrubi's ability to calibrate a 3457A, but I'm
pretty sure he had a VNA cal kit on eBay which was calibrated. I was
suspicious, but I can't recall the exact details. I can't find the
auction, but I'm 99% sure it was goldenrubi.

I know Orin knows about VNAs, so he at least will understand this. But
even if you don't, it should be clear that you can't calibrate a
device properly using a device of the same specification.

Anyway, goldenrubi has two items on eBay now, both related to vector
network analyzer, neither of which have cal certificates, but I
doubted the accuracy of some comments on those auctions. So I deceided
to use the "ask seller a question" and query things. As I suspected,
he does not have a clue. It should be noted

1) One kit (85032B) has a part missing, which he is clear about.
2) The same kit shows some adapters (which I think are not the correct
models), but the adapters are present. The auction says they are not,
so I query that too.

These two things are not central to the problem.

I also strongly suspect two of these parts in the 85032B are not
original, as they have no HP markings on them at all. I have one of
these kits, and parts clearly have HP markings on them.

1) http://www.ebay.co.uk/itm/14143954 is a "TESTED" HP 83032B
typep N calibration kit.
2) http://www.ebay.co.uk/itm/190780743417 is a "TESTED" 85053A 26.5
GHz 3.5mm verification kit.

Bear in mind, the manuals for both devices states the equipment to
verify the performance of the kits is not commericially available. Now
goldenrubi tells me he can't calibrate them, but his reasons are
totally wong. He seems to think that he could calibrate the kits if he
had other kits of the same model. This is totally wrong.

I know for a fact the open and short standards should be checked by
mechanical dimensions, not electrical measurements. I have got that
from someone at Agilent who is a specialist in this area. If you look
at papers on the calibration of these things, you will find things
like laser micrometers are used.

=== My 1st message to  goldenrubi 
Dear goldenrubi,

I'm interested in this 85032B. Can you tell me how it was tested? Can
you provide a calibration certificate? The auction states it does not
come with the APC-7 to N adapters, but they are in the picture. Do you
intend removing them? If so,

I'm also interested in the 3.5 mm verification kit you have in another
auction. I'd like to know again how it was tested and whether it is
calibrated.

Dave

- drkirkby
==

He replies, saying he has the network anayzers these kits belong to,
so that is how he tests them!  He says to calibate them he would
need another calibrated kit of the same model. This is total rubbish
as you can buy the kits easy enough (excepting the 85032B is
obsolete), but the manuals make it clear the equipment to verify the
performance is not commerically available.

 goldenrubi  1st reply to me ==
Dear drkirkby,

I do not have the HP - Agilent 85032-60009 Short in this kit. I have
everything else. We have the Network analyzers that these kits belong
too. That is how we test them out. We cannot calibrate them or provide
certificate because we do not have this HP 85032B full kit and we
would need another kit that was calibrated in order to do a one on one
calibration on my kit. You get everything that is in the picture. I
will not remove any item. The 3.5MM verification kit was tested by us.
we have the equipment to test these kits out. WE do not have the
calibration kit to re-cal my kits on a one on one calibration. so we
cannot cal them. NO standards to work with.

- goldenrubi


I seek clarification, to make sure I have understood him correct

== My second message to goldenrubi 
Dear goldenrubi,

OK, I understand the 85032-60009 Short is missing from the 85032B
calibration kit on auction 4143954. If I understand you correctly,
you can't calibrate the 85032B since you don't have another 85032B -
is that correct? Why does your auction for the 85032B say the adapters
are missing, when there are adapters in the picture? What equipment do
you use to test the 85053A 26.5 GHz 3.5mm verification kit in auction
190780743417? Am I correct in saying you can't calibrate it since you
don't have another 85053A verification kit, but if you had another
85053A you could calibrate it. Let me know if I have understood you
correct. Dave

- drkirkby
===

His reply confirms what I thought.

=== His second reply to me ===
Dear drkirkby,

The short is missing from the picture. There should be 2 shorts, there
is only on. Yes, we need a counter part or other kit that

Re: [volt-nuts] Sn10Pb90

[Volker Esper]

sorry, spelling mistake:
"What do you _want_ it for?"

Remember, those solder alloys are optimized for a specific alloy 
combination only, e.g. Cu-Cu.


Volker


Am 12.08.2013 10:39, schrieb Volker Esper:


Hi Joe,

What are you looking for, Cadmium-Solder, or Sn10Pb90, which is 
Stannum/Plumbum-only?


And what do you what it for? In (very high) precision applications 
there are so many issues to consider that the solder doesn't appear to 
be at a high priority...


Volker


Am 12.08.2013 00:38, schrieb Joseph Gray:
Reading through the archives, I saw that there was some discussion 
about a
safer alternative to cadmium-based solder. The low tin, high lead 
alloy was

recommended as a good low-thermal EMF substitute. However, I did not see
any recommendations on where to buy some of this.

I just did some searching and all I come up with is bar solder, 
mostly from
China. Where can I buy a small quantity of rosin-core 10/90 solder? 
Mouser,
which is my preferred vendor certainly didn't list any. I would think 
that

even 1/2  pound would last me a lifetime.

Joe Gray
W5JG
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Re: [volt-nuts] Sn10Pb90

[Volker Esper]

Hi Joe,

What are you looking for, Cadmium-Solder, or Sn10Pb90, which is 
Stannum/Plumbum-only?


And what do you what it for? In (very high) precision applications there 
are so many issues to consider that the solder doesn't appear to be at a 
high priority...


Volker


Am 12.08.2013 00:38, schrieb Joseph Gray:

Reading through the archives, I saw that there was some discussion about a
safer alternative to cadmium-based solder. The low tin, high lead alloy was
recommended as a good low-thermal EMF substitute. However, I did not see
any recommendations on where to buy some of this.

I just did some searching and all I come up with is bar solder, mostly from
China. Where can I buy a small quantity of rosin-core 10/90 solder? Mouser,
which is my preferred vendor certainly didn't list any. I would think that
even 1/2  pound would last me a lifetime.

Joe Gray
W5JG
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Re: [volt-nuts] Calibration and Certification - Trust and detail

[Dr. David Kirkby]

On 12 August 2013 01:58, Charles Steinmetz  wrote:
> David wrote:
>
>> How useful is this
>>
>> http://www.ebay.com/itm/281149723636 ?
>>
>> On the fact of it, the device would give one a reasonly high
>> confidence something is working readlably well. I wonder if that is
>> good enough for a 3457A.
>
>
> Let's assume that it is still working exactly the same as it was when it was
> calibrated.  The calibration values are recorded to 4-1/2 digits.  So the
> uncertainty is greater than the two LSDs of a 3457A.  Of course, it is
> almost certainly not working exactly the same as it was when it was
> calibrated, which is going to put at least the third LSD of a 3457A in
> question.  So it is good enough for a 3457A only if one is content with a
> 3-1/2 digit verification on a 6-1/2 digit instrument.
>
> Best regards,
>
> Charles

Thank you Charles. Yes, on checking the spec I can see it wont be any use.

Dave
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