The TSC series of transceivers are, high performance, single channel remotely controlled, fully synthesized, 19 inch rack mount VHF/AM radios which operate over the frequency range of 117.975 MHz to 138.000 MHz, with 25 KHz channel spacing. These units feature very high adjacent channel rejection and are intended for use in areas having high RF density. For situations where extreme interference persists, an optional 20 dB receive crystal filter is available. Transmitters are equipped as standard with 20 dB isolators which significantly reduce transmitter inter-mod in areas of high RF concentration (ie., major airports). TSC series transceivers are supplied with a TLI 303 line interface card as standard allowing remote operation via two wire or 4 wire lines and supporting 2175 Hz (ARINC 2300 Hz optional) tone keying, DC keying, current loop or ground keying. Operating power requirement is 110/220 VAC (selectable) with automatic changeover to external DC operation in the event of a mains failure. Transmit output power is 7 Watts for the TSC-4300, 15 Watts for the TSC-4200 and 25 Watts for the TSC-4100. These high quality and reliable transceivers are in daily service with almost every North American air carrier and many international carriers.