[volt-nuts] HP 3458A

[WB6BNQ]

Hi Poul,

I guess you missed my point.

Unless you are a business that relies on a traceable process, such as a real Second
Level Lab, it makes no sense for the hobbyist to spend the money to go beyond the
basic calibration service.  To the hobbyist, for all intent and purpose, the basic
calibration would exceed any reasonable measurement requirement the hobbyist could
come up with.

Unless a hobbyist has a lot of money, the average hobbyist person is not going to be
able to provide a Lab area that would be controllable to within one degree
centigrade.  That is the level needed to make real use of the 24 hour specification
and that specification is using the 3458A as a transfer standard.

The only thing a real Primary Lab, with the capability, could do that would be worth
the value would be to use the JJ array to verify the actual linearity of the A/D of
that specific meter.  That would also evaluate the meter’s internal reference to an
absolute standard.  In all truth, I doubt that is what is being classed as a
so-called “Golden” calibration because the money is not high enough to cover the
time and cost required for a full verification of the meter’s A/D linearity and the
meter’s absolute stability.  HP has already done such work in the verification of
their production line of the 3458A to prove its worth.  That effort, assuming you
accept it, has shown the validity of the circuit design, repeatability and stability
in production units.

The real problem is the average person getting caught up the numbers game where they
have no way in hell proving it one way or another.  They also have no reason for
such so-called extreme accuracy and resolution.  Sure it is a damn good meter and if
you can afford one it is a very nice meter to have.  A hobbyist who owns one should
consider himself as being lucky and that it only cost around $500 to get it
calibrated if you have the means.  They should be especially thankful that they can
have the calibration from a, hopefully, trustworthy source, such as the very maker
of the instrument, at such a reasonable price.

For the hobbyist, making smart use of the instrument with basic calibration and
understanding how to use it properly would be way more profitable then getting
caught up in the numbers game to an insane level.

My two cents.

Bill....WB6BNQ


Poul-Henning Kamp wrote:

> In message <4E3DD8AF.FF938E47 at cox.net>, WB6BNQ writes:
>
> >This response illustrates the absurdity in the whole process.  The so-called
> >"Golden Calibration" is only of value in shifting from a fixed standard to an
> >instrument that can measure "in-between" values to a high degree if done within
> >minutes of the set up.
>
> Bill, think about it for a moment, isn't that exactly what you would want
> your secondary calibration lab to do ?
>
> If you use the 3458A as bench-instrument, you want it to be stable for
> multiple years so you save on calibration cost/cycles.
>
> If you use the 3458A to compare your josephson standard to the customers
> Fluke 73x, you want rock steady short term stability, but the absolute
> precision doesn't really matter, as long as it is stable.
>
> Just because _you_ don't need it, or see the point, doesn't make it "BS".
>
> --
> 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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