Georg Fischer Signet 5924.561 3-9900-1 Signet 9900 Multi-Parameter Transmitter, Field Mount. The Signet 9900 Transmitter provides a single channel interface for many different parameters including flow, pH/ORP, conductivity/resistivity, salinity, pressure, temperature, level, dissolved oxygen, and other sensors that output a 4 to 20 mA signal. The 9900 Transmitter can also be used as a batch controller when a batch module is installed. New in Generation IV: view pH/ORP sensor calibration and sensor usage information stored at the sensor. This feature requires sensor with memory chip and a 2751 Preamp.