[volt-nuts] HP 3458A

[Poul-Henning Kamp]

In message <4E3CE362.D9B12F73 at cox.net>, WB6BNQ writes:

>First, a 'Primary Lab' is one that has attained a very high degree of 
>accuracy and stability in their in-house standards [...]

I think that while your explanation is pretty spot on, it suffers one
bit of terminology confusion.

At the top of the hierarchy you have the "national metrology labs"
which are the ones your government points at, for all matters
pertaining to the Metre Convention.

These may or may not be primary labs in your terminology.

And they may or may not implement all the units of the Metre Convetion,
most only implement a subset and typically focuses on just a few, which
for one reason or other are important for them.  In Denmark the national
lab specializes is conductivity of water, because this is crucially
important for production of insulin.

The important distinction is that they _decide_ what the meter, kg,
second etc. they don't merely try to _reproduce_ it.

If some weird quantum-murphylogical event suddenly changed the speed
of light or the fine structure constant, the national metrology labs
are the ones who decides how that affects the price of butter, so to
speak.

And here's the trick:   Most of them have a josephson voltage
standard and a lot of them are pretty academic, which means that
if you find the right person and bring home baked apple-pie, you
can get a pretty damn good cal of your 3458a for free...


-- 
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.