Re: Calibration Of Electronic Equipment In The Home Workshop
- From: "Anthony Fremont" <spam-not@xxxxxxxxxxx>
- Date: Sun, 4 Mar 2007 04:58:04 -0600
Jim Yanik wrote:
"Anthony Fremont" <spam-not@xxxxxxxxxxx> wrote in
news:12ukcke5br2bha2@xxxxxxxxxxxxxxxxxx:
MassiveProng wrote:
On 2 Mar 2007 15:09:30 -0800, "David L. Jones" <altzone@xxxxxxxxx>
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.
Thanks Jim. It's nice to read something that makes me feel like I still
retain some semblance of sanity. That all seems completely reasonable, and
you didn't even have to curse or make threats. ;-)
.
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- From: Jim Yanik
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