[time-nuts] R&S XSRM Rubidium Standard

KA2WEU at aol.com KA2WEU at aol.com
Sun Sep 17 18:45:33 UTC 2017


correct !
 
 
In a message dated 9/17/2017 1:51:30 P.M. Eastern Daylight Time,  
cjaysharp at gmail.com writes:

Yes.

An instrument with a calibration certificate is not  necessarily accurate
but it's inaccuracies are known and can be compensated  for (but only to the
accuracy of the calibration reference of  course.)



On 17 Sep 2017 17:39, "Magnus Danielson"  <magnus at rubidium.dyndns.org> 
wrote:

> 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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