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Page 63 of 97
Issue: 1.04
an alloy such as tellurium–copper that has a high copper content and low thermal
EMF to pure copper. Brass connectors must NOT be used):
V
I
Voltage
Source
Configure the microK to measure a Default Thermocouple on the 0.125V range
with units of Volts. Use 1 sample per reading and 100 readings in the rolling
statistics (see section 3.6). Select the
Single
tab and clear the statistics. After the
microK has collected at least 100 readings (shown as
Mean of last…
in the
Single
tab, check that the
Mean
value agrees with the applied voltage to within
0.000000250V (0.25µV) and that the standard deviation (
S.D.
) is less than
0.000000050V (0.05µV).
Repeat the procedure with the voltage source set to -50mV.
7.2 Adjusting Calibration
This section describes the procedures for adjusting the internal reference
standards and the input offset voltages. These can be performed by the user or a
third party calibration provider, subject to the availability of the standards
specified below. Isothermal Technology additionally checks the temperature
coefficient of the zener reference and the linearity of the microK against an RBC
(resistance bridge calibration) with an uncertainty of 0.01ppm. We therefore
recommend that you return your microK to Isothermal Technology or one of its
appointed service centres annually for a comprehensive instrument calibration.
There are no potentiometers inside the microK to adjust, calibration is
implemented in software so can be performed without removing the cover from
your microK. Calibration is adjusted via the RS232 interface on the rear of the
microK. Connect the microK to a PC (using a 9-pin null-modem RS232 cable)
