WHAT IS A REPEATER?

A repeater consists of a radio receiver, an amplifier, a transmitter, an isolator, and one or two antennas. The transmitter produces a signal on a frequency that differs from the received signal. This so-called frequency offset is necessary to prevent the strong transmitted signal from disabling the receiver. The isolator provides additional protection. A repeater, when located on top of a high building or tower, can greatly enhance the performance of low power walkie-talkie and mobile Amateur Radio equipment by allowing communications over distances much greater than would be possible without it.

The main W4AVA repeater consists of a radio receiver, amplifier, transmitter, isolator, and a single antenna. Coaxial feedline connects the transmitter/receiver to the antenna and it is the feedline through which the radio signals travel to and from the antenna. The repeater receives incoming signals on 146.025 MHz (or satellite receivers located in the National Capital Region) and retransmits signals on 146.625 MHz. By using devices called "duplexers" the W4AVA repeater can use the same antenna to simultaneously receive and transmit signals. The repeater system also includes a controller, a computer that transmits the FCC-required station identification in voice and "W4AVA/R" in Morse Code. The "R" transmitted in Morse Code after call sign W4AVA indicates that the station is a repeater. The controller also is programmed to require any incoming signal to include a subaudible tone at 107.2 Hertz in order to activate the repeat function and retransmit the incoming signal on 146.625 MHz. The purpose of the subaudible tone is to minimize interference from distant stations or operators transmitting on the repeater's input frequency.