Thermistor Calibration - ILX Lightwave LDX-36000 Series User Manual

Thermistor Calibration

To perform an accurate thermistor calibration, large resistor values are
recommended.
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10 Calculate the slope and offset of the thermistor voltage measurement with the following
11 Send the thermistor voltage calibration to the 36000 using the following command:
12 After measuring and recording the resistance of a 10K resistor, replace the 15K resistor
13 Retrieve the 36000 measurement of the 10K resistance value with the following
14 Verify that the measurement of the 10K resistor is within the accuracy specifications of the
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C A L I B R A T I O N A N D T R O U B L E S H O O T I N G
Set the 36000 display to Temperature by sending the following command: LAS:DIS:T
Set default thermistor measurement calibration by sending the following commands:
LAS:CAL:THERMV1,0
LAS:CAL:THERMI1,0
After measuring and recording the resistance of a 5K resistor, connect it to the two
thermistor sense lines located in the DB9 on the back of the 36000. Measure the voltage
drop across the 5K resistor with a volt meter.
Calculate the current passing through the 5K resistor using Ohms Law. I = V / R
The current passing through the resistor should be 102.4uA. Calculate the offset current
with the following equation:
offset = 102.4uA - measured current
Send the thermistor current offset to the 36000 using the following command:
LAS:CAL:THERMI 1,offset
Retrieve the 36000 measurement of the 5K resistance value with the following command:
Resistance?
After measuring and recording the resistance of a 15K resistor, replace the 5K resistor
with the 15K resistor.
Retrieve the 36000 measurement of the 15K resistance value with the following
command: Resistance?
equations:
slope = (DMM 15K measurement - DMM 5K measurement ) / (36000 15K measurement -
36000 5K measurement )
offset = DMM 15K measurement - (slope * 36000 15K measurement )
LAS:CAL:THERMV slope,offset
with the 10K resistor.
command: Resistance?
instrument.
Thermistor Calibration
LDX-36000 Series
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C H A P T E R
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