Modifying Cable Length
When the sensor is connected to a measurement device with high input impedance, sensor output signals are not
changed by splicing on additional cable in the field. Tests have shown that if the input impedance of the
measurements device is 1 mega-ohm or higher then there is negligible effect on ST series temperature sensors,
even after adding up to 100 m of cable. See Apogee webpage for details on how to extend sensor cable length
http://www.apogeeinstruments.com/how-to-make-a-weatherproof-cable-splice/
). For cable extensions, shielded,
twisted pair cable is recommended, in order to minimize electromagnetic interference. This is particularly
important for long lead lengths in electromagnetically noisy environments.
The precision bridge resistor is located at the pigtail end of the ST-300 cable. Thus, the ST-300 temperature sensor
cables should not be shortened, otherwise the bridge resistor will be removed.
