Which of the following filters is used in a 2-meter band repeater duplexer?

Repeater duplexers require filters with extremely high Q (very sharp tuning) and the ability to handle high transmitter power without degrading or breaking down. Cavity filters are large, physical resonant metal cavities that meet these exact requirements, allowing a transmitter and receiver to use the same antenna simultaneously with minimal interference. Crystal and DSP filters cannot handle the high transmitter power typical of a repeater. Standard L-C (inductor-capacitor) filters are not used here because they lack the extremely high Q necessary to isolate a transmitter and receiver operating just 600 kHz apart on the 2-meter band.