The PRP73 is a range of advanced portable transceivers designed for use in handheld and bodyworn applications. It provides a range of features including CTCSS, DTMF and Selcall signalling, channel scanning and voting, dual watch and password protection. The transceiver is powered from a rechargeable battery unit, which attaches to and forms part of the equipment. The battery may either be removed for charging, or charged whilst attached to the equipment, allowing the transceiver to remain operational. In addition to the standard battery, two other sizes of battery are available, a lightweight version and a high capacity battery, for different duty cycles than those provided by the standard battery. Two versions of the PRP73 are available, a keypad version and a standard version. The standard version has six function keys on the front panel, two function keys on the side and a 2 x 12 character display. Two rotary controls are provided on the top of the unit for volume control and programmable selection. The function keys are also programmable. The keypad version comprises all the functions and facilities of the standard equipment, with the addition of a 12-key numeric keypad. Operation of the PRP73 is controlled by the settings of various software parameters. The operating parameters are stored as data in E2PROM and this data may be programmed into the transceiver using an external data programmer, allowing the PRP73 to be customised to the requirements of a particular user. Calibration data for the Radio PCB is stored in a separate E2PROM on that PCB, thus allowing the Radio PCB to work with any Control PCB. Details of how to programme the transceiver are given in the PRP70 Data Programmer User Guide (Publication Ref. TP1807).