Hello,
after measuring the golden Z201#6 I had the hope that the other Z201#7 that I ordered at the same time would be behaving similar.
But first surprise: the datecode was B1315- (and not B1305- as on the "golden" resistor)
Second surprise: T.C. + hysteresis is much larger.
The results of Z201#7 Datecode B1315- on 21.03.2015
T.C. with box method: 0.818591506 ppm/K
3rd order LMS interpolation referenced to 25 deg
A 0 = -1.43422451376099E-0001
A 1 = 9.64007179982438E-0001
A 2 = -1.26483309879412E-0002
A 3 = -3.34940837358552E-0004
So T.C. at 25 deg is 0.96 ppm/K
max deviation from LMS 2.57933723463504E+0000 ppm (hysteresis + noise)
In the mean time I am in doubt what the data sheet terms
"typ. TCR" and "max spread" really mean.
"typ." seems to be the average value over a large number of batches and samples.
And with "max spread" I am not shure wether the 1 sigma or the 3 sigma limits are meant.
Up to now I had expected that max spread means something with 3 sigma. But I have already
2 samples which are above +/- 0.2 +0.6 ppm/K on Z201 at least for the slope at 25 deg C.
But the data basis is still not sufficient for any statistics.
I have also attached the overview and included Franks results for the 1K00 resistors.
The hysteris cannot be compared directly since the noise
on Franks HP3458A is about a factor 5 lower than my setup
and is determined "graphically" at 25 degrees.
The test fixture for Edwins Ultrohm Plus 805 style resistors (I will refer to them as UP805) is nearly ready.
So I will most probably start with first measurement on 1K resistors tomorrow.
With best regards
Andreas