Re: [time-nuts] Calibration procedures - what is normal?

[Florian Teply]

Am Sat, 13 Feb 2016 18:41:02 +1300
schrieb "Dave Brown" :

> Cobham is a UK based defence and high end security supplier-
> originally formed (not too many years ago)  by their buying out of
> several other companies in their lines of business. More recently
> they have got into aerospace activities.  As you might expect, they
> supply some rather expensive and exotic stuff.  Purchase of Aeroflex
> seems like a step in a different direction but who knows?
> 

Well to me, purchasing Aeroflex sounds very much in line with their
aerospace activities. Aeroflex itself bought a number of smaller
aerospace companies in recent years.
So much that is, that some people insist that buying space-related
companies is all Aeroflex actually does, full stop. ;-)

Florian
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Re: [time-nuts] Calibration procedures - what is normal?

[Clint Jay]

I have to say,  I'm hugely impressed by the Aeroflex 3413 I've bought and
Cobham's customer service response has so far been excellent but I suspect
it will be far too expensive for me to buy repair parts which is a shame.
On 13 Feb 2016 09:14, "Dave Brown" <tract...@ihug.co.nz> wrote:

> Cobham is a UK based defence and high end security supplier- originally
> formed (not too many years ago)  by their buying out of several other
> companies in their lines of business. More recently they have got into
> aerospace activities.  As you might expect, they supply some rather
> expensive and exotic stuff.  Purchase of Aeroflex seems like a step in a
> different direction but who knows?
> DaveB, NZ
>
> - Original Message - From: "Joseph Gray" <jg...@zianet.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com>
> Sent: Saturday, February 13, 2016 6:00 PM
> Subject: Re: [time-nuts] Calibration procedures - what is normal?
>
>
> On Fri, Feb 12, 2016 at 3:43 PM, Richard (Rick) Karlquist
>> <rich...@karlquist.com> wrote:
>>
>> I left Agilent just before the split, but I don't know
>>> anyone there who liked that name.  Or the logo :-)
>>>
>>
>> Another recent name change (acquisition) that is even worse is
>> Aeroflex to Cobham. I realize that Cobham is probably a family name
>> that was used when their business was started eons ago, but geez, in
>> all these years, they couldn't have come up with a better name for the
>> company? Even when it went from IFR to Aeroflex, that wasn't a bad
>> name at all.
>>
>> In the coming fiscal year, we'll be spending close to $100K to buy
>> some Cobham (yuck!) service monitors (or communication analyzers as
>> they like to call them). Going to P25, the venerable HP 8920A just
>> doesn't cut it any more. As for the $100K, we're small potatoes. I was
>> told that an unnamed customer recently bought hundreds of units. It's
>> like that line "A billion here, a billion there, pretty soon, you're
>> talking real money."
>>
>> Joe Gray
>> W5JG
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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>>
>
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Re: [time-nuts] Calibration procedures - what is normal?

[Daniel Watson]

Hi,

I had an interesting experience with a local cal lab when I took in my HP
5334B (Option 010). I'd recently purchased the unit and had no idea of its
calibration history. At the time I wasn't quite a time nut, and I didn't
own a reference to check frequency accuracy myself. I was hoping to get the
counter and its timebase calibrated to use as a reference at home. I
checked the service manual and got the impression that this was part of the
procedure. I also told the tech what I was looking for when I dropped it
off. Can you see where this is going?

A few days later I picked up the unit, and the cal certificate listed the
frequency accuracy as perfect to 9 digits with no adjustment needed. That
raised an eyebrow. When I got it home, I immediately noticed the reference
selector had been switched to external. Sure enough, no adjustment to the
OCXO had been made. They used their lab reference externally during the
procedure. I contacted them, they said they followed the listed procedure
for this counter, but nonetheless offered to help. I took the unit back and
they plugged it in for 10 minutes to let it "stabilize", then gave me the
count of their standard on one of the channels written on a sticky note...

Needless to say, that experience motivated me to get more serious about
this stuff and invest in some good references.

Dan


On Fri, Feb 12, 2016 at 3:14 PM, Joseph Gray  wrote:

> I sent my HP 3457A in for cal. I should be getting it back next week.
> I won't mention where I sent it, but it wasn't Keysight (I don't like
> that name). I recently changed the SRAM battery and purposely did not
> save the cal constants. I bought the meter second hand and it wasn't
> in spec when I bought it. I didn't care what the past data was.
>
> The service manual lists an entire sequence of procedures for
> calibrating this DMM, starting with storing values for zero and full
> scale into the SRAM. All of this is done via the front panel, by
> pushing buttons.
>
> I just found out that this part of the procedure is not normally done
> (at least by the lab I sent the DMM to). With no pre-existing cal
> constants, the tech I spoke to was rather annoyed that he was having
> to spend the time doing the hookups and pushing buttons for each
> function and range to store the zero and full scale values. I was told
> this added an extra hour to the normal procedure.
>
> Not knowing what is normally done in the cal lab, I assumed that the
> entire procedure as listed in the service manual would be done. It
> seems that I was wrong.
>
> In the end, the lab decided not to charge me for the extra time
> involved. I thanked them for that.
>
> My question is, do any cal labs (including Keysight) normally perform
> the zero and full scale procedures as listed in the service manual?
>
> Joe Gray
> W5JG
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Re: [time-nuts] Calibration procedures - what is normal?

[Dave Brown]

Cobham is a UK based defence and high end security supplier- originally 
formed (not too many years ago)  by their buying out of several other 
companies in their lines of business. More recently they have got into 
aerospace activities.  As you might expect, they supply some rather 
expensive and exotic stuff.  Purchase of Aeroflex seems like a step in a 
different direction but who knows?

DaveB, NZ

- Original Message - 
From: "Joseph Gray" <jg...@zianet.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts@febo.com>

Sent: Saturday, February 13, 2016 6:00 PM
Subject: Re: [time-nuts] Calibration procedures - what is normal?



On Fri, Feb 12, 2016 at 3:43 PM, Richard (Rick) Karlquist
<rich...@karlquist.com> wrote:


I left Agilent just before the split, but I don't know
anyone there who liked that name.  Or the logo :-)


Another recent name change (acquisition) that is even worse is
Aeroflex to Cobham. I realize that Cobham is probably a family name
that was used when their business was started eons ago, but geez, in
all these years, they couldn't have come up with a better name for the
company? Even when it went from IFR to Aeroflex, that wasn't a bad
name at all.

In the coming fiscal year, we'll be spending close to $100K to buy
some Cobham (yuck!) service monitors (or communication analyzers as
they like to call them). Going to P25, the venerable HP 8920A just
doesn't cut it any more. As for the $100K, we're small potatoes. I was
told that an unnamed customer recently bought hundreds of units. It's
like that line "A billion here, a billion there, pretty soon, you're
talking real money."

Joe Gray
W5JG
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Re: [time-nuts] Calibration procedures - what is normal?

[Joseph Gray]

On Fri, Feb 12, 2016 at 3:43 PM, Richard (Rick) Karlquist
 wrote:

> I left Agilent just before the split, but I don't know
> anyone there who liked that name.  Or the logo :-)

Another recent name change (acquisition) that is even worse is
Aeroflex to Cobham. I realize that Cobham is probably a family name
that was used when their business was started eons ago, but geez, in
all these years, they couldn't have come up with a better name for the
company? Even when it went from IFR to Aeroflex, that wasn't a bad
name at all.

In the coming fiscal year, we'll be spending close to $100K to buy
some Cobham (yuck!) service monitors (or communication analyzers as
they like to call them). Going to P25, the venerable HP 8920A just
doesn't cut it any more. As for the $100K, we're small potatoes. I was
told that an unnamed customer recently bought hundreds of units. It's
like that line "A billion here, a billion there, pretty soon, you're
talking real money."

Joe Gray
W5JG
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Re: [time-nuts] Calibration procedures - what is normal?

[Joseph Gray]

The consensus seems to be that I was expecting more than I should
have. That's what I get for reading service manuals :-)

Other than the confusion over what I was expecting, I can't fault the
cal lab I sent the meter to. They are charging me a hobbyist-friendly
price and aren't going to charge me for the extra time involved to
re-enter the cal data (I offered to pay). If I were using this for
business, I would probably have used HP/Agilent/Keysight/whatever
they'll be called next month.

When I think about it, I really don't know if the DMM had cal
constants in it when I bought it second hand. I say this because the
battery had previously been replaced. I thought it was original, but
when I pulled the board, I could see obvious signs of hand soldering.
I had asked the previous owner if the battery had been replaced and he
said no. I guess I was lied to. Who knows if the person who replaced
the battery before did things properly, so as to save the cal data.
When I replaced the battery, I purposely didn't bother saving
anything.

Once I get the 3457A back, I'll check my EDC VS330 voltage standard. I
suspect that it is also out of spec. I realize that I should use a
3458A for this, as the specs on the VS330 and the 3457A are similar.
The good news is that the cal lab said that they could probably adjust
the VS330 if needed. I emailed them the manual and asked. They said
they offer a one hour free eval, so if they decide they can't do it,
I'd only be out shipping, if I send it to them.

David Kirby - Yes, I do remember your talking about removing the
battery in your DMM. As for doing it yourself (at least with the
3457A), yes, if you had the proper standards that were also
calibrated. As I recall from reading the service manual weeks ago, the
procedure is just hooking up the appropriate standard for each
function and range, then pushing buttons on the front panel. I don't
have the necessary equipment, so I sent it off.

I agree that it would make more sense to have fitted a second battery,
or at least some pins on the board where you could easily clip in a
temporary battery. Otherwise, you have to solder something in
temporarily. Thankfully, modern equipment uses non-volatile memory
that doesn't need a battery.

Thanks to all for the feedback.

Joe Gray
W5JG


On Fri, Feb 12, 2016 at 4:24 PM, Dr. David Kirkby (Kirkby Microwave
Ltd)  wrote:
> On 12 Feb 2016 21:12, "Joseph Gray"  wrote:
>>
>> I sent my HP 3457A in for cal. I should be getting it back next week.
>> I won't mention where I sent it, but it wasn't Keysight (I don't like
>> that name). I recently changed the SRAM battery and purposely did not
>> save the cal constants.
>
> You may have seen my recent post on the 3457A. I was tempted to do as you
> done, on the assumption that Keysight would adjust the meter to give the
> best possible accuracy rather than just leave something untouched if it was
> within spec.  Someone warned me that if it caused errors at startup,  it
> might be considered needing a repair rather than just calibration.
>
> Did the meter indicate in any way that the cal constants were lost? A POST
> error or similar?
>
>> The service manual lists an entire sequence of procedures for
>> calibrating this DMM, starting with storing values for zero and full
>> scale into the SRAM. All of this is done via the front panel, by
>> pushing buttons.
>
> So does that mean it is something one could do oneself without accurate
> standards?
>
>> I just found out that this part of the procedure is not normally done
>> (at least by the lab I sent the DMM to). With no pre-existing cal
>> constants, the tech I spoke to was rather annoyed that he was having
>> to spend the time doing the hookups and pushing buttons for each
>> function and range to store the zero and full scale values. I was told
>> this added an extra hour to the normal procedure.
>
> Ouch.
>
> I assume this means that your meter is probably calibrated more accurately
> than it would have been had any settings left unchanged if they were in
> spec.
>
> I have just bought a battery and intend fitting it soon.  I might ask
> Keysight about the constants.
>
> I really can't understand why they don't put two battery holders and a
> couple of diodes so a good battery in an one would be ok. Having to mess
> around desoldering batteries and hooking up power supplies seems crazy to
> me.
>
> Dr David Kirkby
> Managing Director
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3
> 6DT, United Kingdom
> Registered in England and Wales as company number 08914892
> http://www.kirkbymicrowave.co.uk/
> Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT)
> ___
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> and follow the instructions there.
>

Re: [time-nuts] Calibration procedures - what is normal?

[paul swed]

Joe
I will believe they only do that procedure in a real repair.
I had to do the same thing on a tek 2465b scope. O man what a complete pain
in the rear and literally 8+ hours of work. So I can fully appreciate the
reality that a Calibration is a check and trim for accuracy. Most likely an
hour or so in total.
Regards
Paul
WB8TSL

On Fri, Feb 12, 2016 at 3:14 PM, Joseph Gray  wrote:

> I sent my HP 3457A in for cal. I should be getting it back next week.
> I won't mention where I sent it, but it wasn't Keysight (I don't like
> that name). I recently changed the SRAM battery and purposely did not
> save the cal constants. I bought the meter second hand and it wasn't
> in spec when I bought it. I didn't care what the past data was.
>
> The service manual lists an entire sequence of procedures for
> calibrating this DMM, starting with storing values for zero and full
> scale into the SRAM. All of this is done via the front panel, by
> pushing buttons.
>
> I just found out that this part of the procedure is not normally done
> (at least by the lab I sent the DMM to). With no pre-existing cal
> constants, the tech I spoke to was rather annoyed that he was having
> to spend the time doing the hookups and pushing buttons for each
> function and range to store the zero and full scale values. I was told
> this added an extra hour to the normal procedure.
>
> Not knowing what is normally done in the cal lab, I assumed that the
> entire procedure as listed in the service manual would be done. It
> seems that I was wrong.
>
> In the end, the lab decided not to charge me for the extra time
> involved. I thanked them for that.
>
> My question is, do any cal labs (including Keysight) normally perform
> the zero and full scale procedures as listed in the service manual?
>
> Joe Gray
> W5JG
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
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Re: [time-nuts] Calibration procedures - what is normal?

[Scott McGrath]

'Normal' calibration is a performance check and adjustments as required 

Performance checks are applying stimulus and checking instrument response is 
within the acceptable range.

A Full calibration is adjust each parameter to as close as practicable to ideal 
value and may include new cal constants and is generally far more expensive 
than a normal calibration 

Content by Scott
Typos by Siri

> On Feb 12, 2016, at 3:14 PM, Joseph Gray  wrote:
> 
> I sent my HP 3457A in for cal. I should be getting it back next week.
> I won't mention where I sent it, but it wasn't Keysight (I don't like
> that name). I recently changed the SRAM battery and purposely did not
> save the cal constants. I bought the meter second hand and it wasn't
> in spec when I bought it. I didn't care what the past data was.
> 
> The service manual lists an entire sequence of procedures for
> calibrating this DMM, starting with storing values for zero and full
> scale into the SRAM. All of this is done via the front panel, by
> pushing buttons.
> 
> I just found out that this part of the procedure is not normally done
> (at least by the lab I sent the DMM to). With no pre-existing cal
> constants, the tech I spoke to was rather annoyed that he was having
> to spend the time doing the hookups and pushing buttons for each
> function and range to store the zero and full scale values. I was told
> this added an extra hour to the normal procedure.
> 
> Not knowing what is normally done in the cal lab, I assumed that the
> entire procedure as listed in the service manual would be done. It
> seems that I was wrong.
> 
> In the end, the lab decided not to charge me for the extra time
> involved. I thanked them for that.
> 
> My question is, do any cal labs (including Keysight) normally perform
> the zero and full scale procedures as listed in the service manual?
> 
> Joe Gray
> W5JG
> ___
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Re: [time-nuts] Calibration procedures - what is normal?

[Richard (Rick) Karlquist]

On 2/12/2016 12:14 PM, Joseph Gray wrote:

I sent my HP 3457A in for cal. I should be getting it back next week.
I won't mention where I sent it, but it wasn't Keysight (I don't like
that name). I recently changed the SRAM battery and purposely did not


I left Agilent just before the split, but I don't know
anyone there who liked that name.  Or the logo :-)

You need to understand that the mission of service depots at
Agilent was mainly to be profit centers.  They were not there
to make customers happy in order to enhance Agilent sales.
At best, they needed to do warranty repairs to support equipment
under warranty, but even the whole warranty thing was a way
to make extra money, not to sell instruments in the first
place.  What you describe is perfectly consistent with my
experience using them as an internal customer.  BTW, they
charge internal customers the same high prices they charge
for external customers.  There is an attitude that it is not
worth making reliable products because they can make so
much money fixing them.  Consider yourself lucky you got
the extra effort.  They remind me of car dealer service
departments, in terms of the business model.  Specifically,
the "tune up" racket or the XXX,000 mile "service" racket.

Rick
N6RK



Not knowing what is normally done in the cal lab, I assumed that the
entire procedure as listed in the service manual would be done. It
seems that I was wrong.

In the end, the lab decided not to charge me for the extra time
involved. I thanked them for that.

My question is, do any cal labs (including Keysight) normally perform
the zero and full scale procedures as listed in the service manual?

Joe Gray
W5JG

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Re: [time-nuts] Calibration procedures - what is normal?

[Clint Jay]

Generally, whenever I've had a non manufacturer 'calibration' it's been a
certification service that tells you your equipment is within spec and
gives you the variances and probability of uncertainty,  a pass/fail test.

Where equipment was out of spec then any service to bring it within spec
was usually charged extra but the level of equipment we needed meant the
test year was thrown away and new was purchased  it was cheaper than having
it adjusted.

I sent my HP 3457A in for cal. I should be getting it back next week.
I won't mention where I sent it, but it wasn't Keysight (I don't like
that name). I recently changed the SRAM battery and purposely did not
save the cal constants. I bought the meter second hand and it wasn't
in spec when I bought it. I didn't care what the past data was.

The service manual lists an entire sequence of procedures for
calibrating this DMM, starting with storing values for zero and full
scale into the SRAM. All of this is done via the front panel, by
pushing buttons.

I just found out that this part of the procedure is not normally done
(at least by the lab I sent the DMM to). With no pre-existing cal
constants, the tech I spoke to was rather annoyed that he was having
to spend the time doing the hookups and pushing buttons for each
function and range to store the zero and full scale values. I was told
this added an extra hour to the normal procedure.

Not knowing what is normally done in the cal lab, I assumed that the
entire procedure as listed in the service manual would be done. It
seems that I was wrong.

In the end, the lab decided not to charge me for the extra time
involved. I thanked them for that.

My question is, do any cal labs (including Keysight) normally perform
the zero and full scale procedures as listed in the service manual?

Joe Gray
W5JG
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Re: [time-nuts] Calibration procedures - what is normal?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 12 Feb 2016 21:12, "Joseph Gray"  wrote:
>
> I sent my HP 3457A in for cal. I should be getting it back next week.
> I won't mention where I sent it, but it wasn't Keysight (I don't like
> that name). I recently changed the SRAM battery and purposely did not
> save the cal constants.

You may have seen my recent post on the 3457A. I was tempted to do as you
done, on the assumption that Keysight would adjust the meter to give the
best possible accuracy rather than just leave something untouched if it was
within spec.  Someone warned me that if it caused errors at startup,  it
might be considered needing a repair rather than just calibration.

Did the meter indicate in any way that the cal constants were lost? A POST
error or similar?

> The service manual lists an entire sequence of procedures for
> calibrating this DMM, starting with storing values for zero and full
> scale into the SRAM. All of this is done via the front panel, by
> pushing buttons.

So does that mean it is something one could do oneself without accurate
standards?

> I just found out that this part of the procedure is not normally done
> (at least by the lab I sent the DMM to). With no pre-existing cal
> constants, the tech I spoke to was rather annoyed that he was having
> to spend the time doing the hookups and pushing buttons for each
> function and range to store the zero and full scale values. I was told
> this added an extra hour to the normal procedure.

Ouch.

I assume this means that your meter is probably calibrated more accurately
than it would have been had any settings left unchanged if they were in
spec.

I have just bought a battery and intend fitting it soon.  I might ask
Keysight about the constants.

I really can't understand why they don't put two battery holders and a
couple of diodes so a good battery in an one would be ok. Having to mess
around desoldering batteries and hooking up power supplies seems crazy to
me.

Dr David Kirkby
Managing Director
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3
6DT, United Kingdom
Registered in England and Wales as company number 08914892
http://www.kirkbymicrowave.co.uk/
Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT)
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