"Anthony Fremont" wrote in
:

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.

The "basic fact" here is that we were talking about adjusting a 3%
scope with a .03% meter. Now that the number are back where they
belong, please procede to restate your case. The scope's vertical
sensitivity could easily be adjusted to within 3% using said meter,
now can't it? Just like Keith says......




Actually,one CAN calibrate an instrument to a greater accuracy than it's
specified accuracy,-for a short time-;it's called a transfer standard.
Of course,there are limits to how much greater accuracy you can
achieve,based on resolution and repeatability.

For ordinary cals,your standard should be at least 4x better than the DUT.
10x is great.


--
Jim Yanik
jyanik
at
kua.net