Apparatus and instruments for recording, transmitting and/or receiving sound, data or images, namely radio transmitters and receivers, trunked radio network systems and simulcast radio network systems, namely, networked mobile radio transceivers, a base station, a repeater, a computer-controlled database for allocation of radio frequencies, and a computer control module; portable and mobile radio apparatus, namely handheld radios, vehicle mounted radios, portable radio telephones and parts and fittings therefore; radio network equipment, namely base stations, repeater stations, site controllers and antennas, modules for base and repeater stations, receiver and transmitter modules, exciters, duplexers, combiners, amplifiers, monitors, alarms, speakers, software for control and channel change, circuit breakers, fans, filters, transformers, cavity resonators, fuses, insulators, condensers, inductors, resisters, switches, relays, connectors, plugs and sockets; power supplies for base and repeater stations; radio site controller equipment, namely, microphones, display terminals; rack frames for mounting of radio equipment; batteries for mobile and portable radio equipment; position and indicator attachments for mobile and portable radio equipment; cellular telephones and hands-free speaker kits for use therewith; digital voice protectors; single sideband communication radios and transmitters