[time-nuts] R&S XSRM Rubidium Standard
KA2WEU at aol.com
KA2WEU at aol.com
Sun Sep 17 12:42:12 EDT 2017
Simply call it " Make it to meet specification", N1UL
In a message dated 9/17/2017 12:39:32 P.M. Eastern Daylight Time,
magnus at rubidium.dyndns.org writes:
Hi,
The word "calibration" is overloaded with multiple meanings, and
incompatible too.
"calibration" is often used to describe adjustments to make a device
operate correctly, such as passing the performance checks.
"calibration" in legal traceability is about measure the performance
against references to form a traceable record of deviations from the
norml. This may include adjustment to ease compensation, but this is not
necessary. Regardless of wither adjustments where done or not, the
calibration record will indicate the errors that then needs to be
applied to the measurement for the measurement to be traceable, and this
in itself requires documented knowledge about how to do the measurement.
Otherwise it's just a fancy indication.
Adjustment to a reference thus do not imply legal traceability, or even
full functionality.
For full functionality, you have to go through the performance check and
see that all values is within limits.
"calibration" can thus imply different things.
I regularly see people use these terms inconsistently. That people get
disappointed when they get the wrong thing is to be expected.
Cheers,
Magnus
On 09/17/2017 05:23 PM, Scott McGrath wrote:
> As to the point most modern instruments have self calibration, Most of
the time 'calibration' is simply the performance check adjustments are not
performed unless necessary
>
> The difference being the instruments used in performance test are
traceable to a national standards body.
>
> So whats referred to as calibration is in reality performance validation.
>
> How do I know this by becoming friendly with the local lab and years ago
when i worked for govt i used to moonlight at one of the local cal labs.
>
>> On Sep 17, 2017, at 8:57 AM, KA2WEU--- via time-nuts
<time-nuts at febo.com> wrote:
>>
>> Modern test and radio equipment have self calibration capabilities,
older
>> analog do not. Calibration is not always need for just simple test,
but
>> for specification conformation it is useful. A bit of luck also
helps.
>>
>>
>>
>>
>> In a message dated 9/17/2017 8:08:00 A.M. Eastern Daylight Time,
>> drkirkby at kirkbymicrowave.co.uk writes:
>>
>>> On 15 Sep 2017 10:45, "Scott McGrath" <scmcgrath at gmail.com> wrote:
>>>
>>> Precisely my point, But when purchasing i expect to pay for a
>> calibration at a minimum.
>>
>> I have on occasions requested sellers to send an item to the
manufacturer
>> (Agilent or Keysight) for calibration *before* shipping it to me,
offering
>> to pay the calibration cost, but stating that I expect a full refund
if the
>> item fails the calibration.
>>
>> If a test equipment dealer is confident that something is working
well,
>> they should not object to sending it to the manufacturer for
calibration,
>> as long as the buyer is willing to pay.
>>
>> Of course if a seller knows little about something, they are not
going to
>> do this, but the item should be appropriately priced.
>>
>> One UK seller (grace1403) declined to send an Agilent N9912A FieldFox
to
>> Agilent, because "Agilent were too fussy"., failing items for trivual
>> issues. But he did agree to send it to one of the cal labs he uses. I
>> thought it was a waste of time going to one of the less fussy outfits,
>> but
>> bought it anyway. It was then clear on receipt that it was faulty.
(The
>> spectrum analyser functionality was ok, but it didn't work as a network
>> analyzer). He took it back, but then advertised it on eBay 6 months
>> later. When asked, he said nothing had been done to it.
>>
>> eBay rules about who pays the return shipping charge for an item that
is
>> "not as described' keep changing, and may be different on different
sites.
>> But on a heavy item shipped internationally, the postage cost can be
>> comparable or exceed the calibration cost.
>>
>> Dave.
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