[volt-nuts] Traveling Standards - Measuring Protocol

[WarrenS]

Bob

First I'd like to say that what your doing is a great idea and could be a 
great benefit to the Volt nut group.
Now for some comments that I hope you will find useful to get the most from 
this exercise.

I'm still hoping you will post more details and if need be get suggestions 
for the measurement that YOU should make before sending the TS out.

When doing short term stability testing better to do it at a Higher 
resolution than 1.7 PPM / count.
One way to do that is to put your 6 digit voltmeter on the 1V or better yet,
the 0.1V range and measure the difference between the Device you're testing 
and
a similar stable non-effected voltage such as a second device of the same 
type that is not being subject to the things you're testing for.
Then taking into consideration that noise measurements are the RMS sum of 
the two devices and Drift measurements are the Difference between devices,
it is possible to greatly increase the accuracy of the measurements.

Also very useful to measure the actual Temperature Coefficient of the 
devices so that the temperature readings have more meaning.

When evaluation precision voltage references,
I find it very helpful to make a High Resolution strip chart recording, be 
it Analog or Digital,
Preferable showing Both temperature and voltage.
For an example of how I get much better than 0.1 PPM resolution using 50 
year old technology,
See attached plot comparing two 10 volt devices, using a slow, dual channel 
analog Rustrak recorder and Fluke 845A/B null meter

Just my two cents worth to the bigger picture.
It is hard to properly evaluate a precision Voltage source unless you first 
know the measurement uncertainties 'aka noise' including any Temperature 
Coef.
AND if the temperature coef is known and not zero (over the measurement 
temperatures), why not add a simple compensating voltage to reduce the 
effect of temperature to insignificant levels?

ws

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[volt-nuts] Traveling Standards - Measuring Protocol
Bob Smither smither at c-c-i.com

I guess it makes sense to define the set of measurements to be made on a
Traveling Standard and how those measurements are to be made.  I have
put a draft protocol for making TS measurements here:
   http://c-c-i.com/tsp
This is all pretty new to me, so I would appreciate any feedback from
the list members, especially those that have agreed to make measurements.

Thanks!
-- 
Bob Smither, PhD                                 Circuit Concepts, Inc.
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