[time-nuts] R&S XSRM Rubidium Standard

[KA2WEU at aol.com]

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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