Sensor readings are negative (-) or zero:
- Check for proper wiring of the LI-200R-BL (see Multiplier for use with LI-200R-BL (3-wire bare leads)), 2220 Millivolt Adapter (Connecting the 2220 Millivolt Adapter), or LI-200R-SMV Pyranometer (LI-200R-SMV Pyranometer).
- Make sure the proper sign was used on the multiplier entered into the LI-1500, LI-1400, or LI-250A, or other recording device (Calibration Constants and Multipliers). If the number is entered without the negative sign, readings will be zero in the LI-1500 and negative in the LI-1400 and LI-250A.
Sensor readings are incorrect:
- Make sure the meter or logger is properly configured, including entering the sensor's correct calibration multiplier. Note that multipliers are different from the calibration constant, and there are different multipliers for use with millivolt adapters (see Calibration Constants and Multipliers).
- Check the sensor's last calibration. Certificates of calibration are available at: www.licor.com/support/. Enter the sensor's serial number in the calibration data search box. Certificates include multipliers and the sensor's last calibration date. LI-COR recommends factory recalibration for radiation sensors every two years (Factory Recalibration).
- Check for loose cable connections. Moisture on connections can also cause erroneous readings.
- Check the sensor cable for damage, including nicks, cuts, or sharp bends.
- Contact LI-COR technical support (envsupport@licor.com) if you are unable to resolve the issue.