"Anthony Fremont" wrote in
:

Jim Yanik wrote:
"Anthony Fremont" wrote:

MassiveProng wrote:
On Sun, 4 Mar 2007 04:23:21 -0600, "Anthony Fremont"

A .03%
METER CAN BE USED, ESPECIALLY WHEN THAT METER IS AVAILABLE WITH
NIST CERTS, NOW CAN'T IT????

NOPE.

Now tell us why not? Exactly what kind of standard is required to
adjust a scope's vertical response to 3% as it's specs state?

0.75% or better accuracy.(4X or better)
(and that would be "adjust to within 3%". the actual result may be
better than 3%;you just can't depend on it staying that way for any
length of time.)

Thanks Jim, I feel like I finally heard something I could put some
stock into. Just to set the record straight, would it be legitimate
to "certify" a device to 3% (DUT specs) using a .03% accurate DMM that
has an NIST cert? Really, it's just a matter of personal curiosity
now.




I'd be leery of that method because vertical gain check is generally done
with a dynamic signal(calibrated sq.wave),to eliminate drift of your
reference (ground) position.Like a TEK PG506.(I wish I had one.)

IIRC,you used a DC source "transfer calibrated" with the DMM to check the
vert.gain.So,literally,the DMM was the "standard" used as the reference,and
that would be listed on the cert.,along with the DC supply.
You just have to be careful to recheck the 0v reference trace position to
be sure it didn't drift.

Gain is usually adjusted on one attenuator setting,and the other ranges
checked to see that they are WITHIN the 3% tolerance,as the attenuators
themselves are usually not adjustable for gain,unless it's a differential
amp,like the 7A13.(don't know about scopes other than TEK.)

--
Jim Yanik
jyanik
at
kua.net