Calibration Adjustments; Thermistor Calibration - ILX Lightwave Temperature Controller LDT-5525 User Manual

Calibration Adjustments

There are two calibration adjustments that need to be made for the LDT-5525
Temperature Controller. They are calibration of sensor measurement, and
calibration of the ITE current measurement and limit circuits.
If a problem arises during calibration which prevents its normal completion, the
calibration may be aborted with no ill effects by simply pressing the OUTPUT
switch. This is possible because the calibration values are not saved to
non-volatile memory until the last step of each calibration procedure.

Thermistor Calibration

The following procedure is for calibrating the 100 µA and 10 µA constant current
sources so that the thermistor resistance measurements for these ranges will be
as accurate as possible. This procedure calibrates the resistance measurements
of the thermistor. This procedure does not calculate C1 and C2. For information
on calibrating the thermistor sensor, see Appendix A.
Calibration may be aborted by pressing the OUTPUT switch.
06_07
M A I N T E N A N C E A N D T R O U B L E S H O O T I N G
a Set the SENSOR SELECT switch (back panel) to the 100
0.99, C2 to 2.57.
b Measure and record the exact resistance of your 4 K
film resistors. A 4-point probe resistance measurement is recommended.
c Connect the 4 KΩ metal film resistor to the sensor input of the LDT-5525
Temperature Controller (pins 7 and 8).
d Enter the sensor calibration mode by pushing the MODE and SENSOR CAL
switches at the same time. After this, the display will indicate the sensor resistance in
KΩ. Allow the measurement to settle for about three seconds.
e Press and hold in the ENBL switch and turn the ADJUST knob until the display
indicates the same resistance you recorded for the 4 KΩ metal film resistor.
f Release the ENBL switch and wait for the VIEW SET indicator (LED) to be unlit.
Replace the 4 KΩ resistor with the 40 KΩ metal film resistor (for 100
metal film resistor (for 10
Ten seconds after the ENBL switch is released, the LDT-5525 Temperature
Controller will store the calibration data in non-volatile memory.
Press the DISPLAY switch three times to rotate the display back to the SENSOR
mode.
g Switch the SENSOR SELECT switch to the 10
h After calibration, the I LIMIT will be automatically set to 4.00 Amps. Reset the I LIMIT
to the desired value.
Calibration Adjustments
µ
A). After three seconds, repeat Step e with this resistor.
µ
A position and repeat Steps c - f.
µ
A position. Set C1 to
Ω Ω
, 40 K , and 400 KΩ metal
µ
A) or 400 KΩ
LDT-5525
3
C H A P T E R
21