The 777 Leveling Preamplifier provides up to 40 dB of gain control within an operational bandwidth of 10kHz to 220MHz for constant-field rfi susceptibility testing, power-output control, modulation envelope feedback, and simulation of current or voltage sources. Employing a front-panel attenuator that permits level adjustment of rf signal input the unit is compatible with a wide variety of rf sources, including function and sweep generators and frequency synthesizers. The minimum power output is 10 mw and the nominal input and output impedance is 50-ohms.