The Site Master (Figure 1-1) is a hand held S21 (transmission gain or loss), SWR/RL (standing wave ratio/return loss), and Distance-To-Fault (DTF) measurement instrument that includes a built-in synthesized signal source and an optional power monitor. It uses a keypad to enter data and a liquid crystal display (LCD) to provide a graphical indication of S21, SWR, or RL over the selected frequency range. The Site Master has a built-in distance-to-fault (DTF) capability. It is capable of up to two hours of continuous operation from a fully charged internal battery and can be operated from a 12.5 dc source (which will also simultaneously charge the battery). Built-in energy conservation features can be used to extend battery life over an eight-hour work day. The Site Master is designed for measuring transmission gain/insertion loss, SWR, return loss, or cable insertion loss and locating faulty RF components in antenna systems. Power monitoring and bias tee capabilities are available as options. The displayed trace can be scaled and/or enhanced with settable frequency markers and/or a limit line. A menu option provides for an audible “beep” when the limit value is exceeded. To permit use in low-light environments, the LCD can be backlit using a front panel key.