[volt-nuts] JJA progress report

Tom Miller tmiller11147 at verizon.net
Sun Feb 16 15:24:25 EST 2014 

How about the need for liquid He refrigeration? Will this bargain based JJA 
have a closed loop cooling system?

Sure sounds interesting though.

Tom

----- Original Message ----- 
From: "Joe Hobart" <nova at npgcable.com>
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Sent: Sunday, February 16, 2014 2:54 PM
Subject: Re: [volt-nuts] JJA progress report


> Thanks to the DOD and radio waves, accurate frequency is available at most
> places on Earth.  SPRTs and more robust Reference PRTs have been available 
> for
> many years.
>
> Frequency to one part in a thousand million is easy.  Measuring 
> temperature to
> 0.1 degree C is also easy; controlling temperature may not be as easy.
>
> What are the frequency, temperature, and other requirements for the
> "inexpensive" JVS systems NIST has been developing?
>
> How many similar JVS/JJA units does a major test equipment company like 
> Agilent
> or Fluke have at any one location?
>
> Joe
>
>
> On 2/16/2014 12:00 PM, Chuck Harris wrote:
>> There are a host of things that will cause a JJA to be
>> off voltage... not the least of which is temperature and
>> frequency.
>>
>> Absent other standards to compare with your JJA, you are
>> really operating in the blind.
>>
>> The only major advantage to the JJA, and the reason it is
>> given primary standard status, is it relates voltage, to
>> frequency.  If the pumping frequency is offset for some
>> reason, the voltage will be wrong by a similar amount.
>>
>> Do you imagine that NIST uses only one JJA to hold the
>> nation's standard volt?
>>
>> -Chuck Harris
>>
>> Tom Knox wrote:
>>> The physics of a properly run JJA will always produce the same result so 
>>> you do
>>> not need additional units for comparison. That is the point of a world 
>>> wide
>>> quantum voltage standard defined as K
>>> J-90                       = 483 597.9 GHz/V                     . Just 
>>> has the
>>> Hyperfine Transition of Cesium at about 9.192631770GHz is used to define 
>>> the
>>> second. What is neat about the work NIST has done recently is that it 
>>> has
>>> automated the System for ease of use and reduced the price to the point 
>>> that it
>>> should see much wider use in day to day metrology.  Having your Agilent 
>>> 3458A
>>> calibrated on a JJA may not yield much difference over a Fluke 5730A 
>>> cal, but
>>> once
>>> the meter has been run a few years characterizing the A to D converter 
>>> and 10VAC
>>> range would only need to be done once and could substantially improve
>>> performance.
>>> I personally think that the face of calibration will change in coming 
>>> years,
>>> rather then simple time based cal periods, instruments will contain 
>>> complex
>>> environmental sensor packages that will constantly monitor the 
>>> instruments
>>> environment . S o calibration will be based more on the instruments 
>>> exposure to
>>> extreme conditions then simple time. I bet the act of shipping has more 
>>> effect on
>>> cal then years sitting in a lab. So if for example a 3458A was put in an
>>> environmental chamber on a shaker table I am sure we find that up to a 
>>> certain
>>> point enviromental conditions would have little effect on cal but at 
>>> some point
>>> would have a major effect. Once documented the cals would be based more 
>>> on
>>> environmental exposure. In addition I am sure some environmental effects 
>>> on cal
>>> are repeatable and could be documented so if monitored they could be 
>>> compensated
>>> for extending time between cals. So in the future you would see your 
>>> instrument
>>> display "environment conditions exceeded" "cal require", with perhaps 
>>> even a
>>> display of currently instrument uncertainty.  This could change the face 
>>> of
>>> calibration and become a multi-billion dollar industry.
>>>
>>> Thomas Knox
>>>
>>>
>>>
>>>> Date: Sun, 16 Feb 2014 07:06:18 -0700 From: nova at npgcable.com To:
>>>> volt-nuts at febo.com Subject: Re: [volt-nuts] JJA progress report
>>>>
>>>>
>>>> If Earth is subjected to a GRB strong enough to damage ground based
>>>> electronics, we are all going to have much more urgent problems than 
>>>> wondering
>>>> if a JVS is operating properly.  Same for an EMP.  Lightning, however, 
>>>> might
>>>> pose a more localized and serious threat.
>>>>
>>>> Part of your training as an expert operator will include techniques to 
>>>> dissuade
>>>> various critters from considering the JVS for their burial ceremonies.
>>>>
>>>> Carrying your best zener reference to the nearest facility with another 
>>>> JVS
>>>> would be less expensive than buying and operating a second or third 
>>>> system.
>>>>
>>>> Joe
>>>>
>>>>
>>>> On 2/16/2014 12:58 AM, cheater00 . wrote:
>>>>> How do you know the primary standard is not off? That is, how do you 
>>>>> know it's
>>>>> still "primary"? Maybe a gamma ray burst from a supernova damaged some 
>>>>> of the
>>>>> machinery inside, or a colony of crazy ants crawled in and died 
>>>>> inside.
>>>>>
>>>>> D.
>>>>>
>>>>> On Sat, Feb 15, 2014 at 10:10 PM, Joe Hobart <nova at npgcable.com> 
>>>>> wrote:
>>>>>>
>>>>>> These devices are primary standards; you don't need three; you 
>>>>>> probably
>>>>>> don't even need two.  If certain conditions are met, conditions you 
>>>>>> can
>>>>>> check/verify, they will accurately generate the desired voltages.
>>>>>>
>>>>>> What you will probably want are at least three good zener type 
>>>>>> voltage
>>>>>> standards and a constant temperature environment.  The three will 
>>>>>> serve as a
>>>>>> day to day standard and reality check on the JJA.  And you need to 
>>>>>> really
>>>>>> learn how to operate the JJA standard, so you can detect and correct 
>>>>>> any
>>>>>> problems.
>>>>>>
>>>>>> Joe Hobart Flagstaff, Arizona
>>>>>>
>>>>>>
>>>>>> On 2/15/2014 1:17 PM, Gordon DeWitte wrote:
>>>>>>> Clearly need three (or some higher odd number) so they can vote...
>>>>>>>
>>>>>>> Gordon
>>>>>>>
>>>>>>>
>>>>>>> On Sat, Feb 15, 2014 at 2:51 AM, Poul-Henning Kamp
>>>>>>> <phk at phk.freebsd.dk>wrote:
>>>>>>>
>>>>>>>> In message
>>>>>>>> <1392413149.25851.YahooMailNeo at web142405.mail.bf1.yahoo.com>, Randy
>>>>>>>> Evans writes:
>>>>>>>>
>>>>>>>>> We'll all probably want a spare unit also.
>>>>>>>>
>>>>>>>> Two, how can you know which one fails, if you only have two ?
>>>>>>>>
>>>>>>>> -- Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20 
>>>>>>>> phk at 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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