Campbell Scientific NR-LITE2 Net Radiometer - Manual (Page 26)

NR-LITE2 Net Radiometer
8. Maintenance
The radiometer is an ‘all weather’ instrument and is very stable, but should be
handled with care. It requires little periodic maintenance, apart from cleaning
the sensor surfaces carefully with a soft cloth using water or alcohol.
The NR-LITE2 should be recalibrated every two years. An RMA number is
required before returning the sensor for recalibration; refer to the Assistance
section in the beginning of this manual for more information.
9. Troubleshooting
9.1 Checking Sensor Operation
To effectively check the instrument’s operation, you will need:
• NR-LITE2
• Voltmeter, range 0 to 50 mV, with an input impedance greater than
5000 Ohms
• Light source
• Table or bench
Position the radiometer so that its downward facing sensor is about 10 mm (0.4
in) above a flat surface (table or bench), and the upwards facing sensor is
facing the light source (lamp). Do not touch the sensor head itself, as this will
introduce thermal shocks. Hold the instrument only by its mounting arm at all
times.
Follow the procedure outlined below:
1. Connect the NR-LITE2 wires to the voltmeter. Connect the red wire to the
positive lead and the blue wire to the negative lead.
2. Select the most sensitive range on the voltmeter.
3. With the lamp switched off, read the sensor output signal — allow a
minute or so for the signal to fully stabilize.
4. Switch on the lamp. The sensor should now produce a higher positive
reading.
5. Turn the lamp off again, when the signal should slowly return to its
original level, proving the sensor’s sensitivity to light.
6. Turn the sensor upside down. The signal value should reverse in sign; a
+10 mV signal should become a ─10 mV signal. Don’t worry if the two
values are not exactly the same (up to 10% difference) as the sensor
profiles can vary. After completing this test, return the sensor to its
original orientation and let it stabilize.
7. Put your hand over the upper sensor. Assuming that your hand is at a
higher temperature than the sensor, the positive reading should increase.
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