The 1311A Audio Oscillator is a complete compact and self-contained audio oscillator with 11 fixed frequencies from 50Hz to 10kHz (50,60,100,120,200,400, and 500Hz, 1,2,5, and 10kHz). It is normally used in audio-frequency bridge measurements and is normally included in many GR impedance-measuring systems. Power output is 1 watt into a matched load and voltage output is continuously adjustable with a maximum output of 100 V into an open circuit. Distortion is less than 0.5% under any load condition. External synchronization is also provided via 1 V reference signal. The unit ensures at least 0.5 watt into any load from 0.08 to 8000-ohms.