MassiveProng wrote:

On 2 Mar 2007 15:09:30 -0800, "David L. Jones"
Gave us:


Which is why you do it for each range and then spot check it to see
that there is no funny business. Perfectly valid technique for home
calibration of a scope vertical scale.

Dave


It doesn't matter how many "places" you "spot check" it, you are not
going to get the accuracy of your comparison standard on the device
you intend to set with it. What you do is take the basic INaccuracy
of the device needing to be set, and add to it the basic INaccuracy of
the standard to which you are setting it. You CANNOT get any closer
than that. So, a 0.5% meter, and a 0.5% scope cannot be used together
to make the scope that accurate. You need a *finer* standard than the
accuracy level you wish to achieve.

You need to understand that as a basic fact, chucko.
Furthermore, an analog scope cannot measure better than 1% (ie 0ne
part in 100 of what is on the scope face).
Now one can "cheat" by using a precision offset differenced with an
input and that difference amplified to *display* (part of) that
difference: note the "Z", the "W", and the more modern "7A13" type plugins.
But *on the screen*, i defy anyone to consistently "read" better than
one part in 100 (ie if 10 divisions on screen, read to better than 1
division on a consistent basis.
Thus, for a scope, one might use standards good to 5 or more places,
but the result will be no better than what has been called "slide rule
accuracy".
Do you believe all 15 digits of each and every number in a computer
printout?