The type J Signal Generators provide 1 watt output into 600 ohms, isolated from earth, over a frequency range of 15 c/s to 50 kc/s. A 5 ohm source is also provided giving a maximum output of not less than J watt. The instrument contains a resistance-capacitance bridge Oscillator feeding via a buffer valve into an output stage. The stabilization of the Oscillator and the feed-back on the output stage provide a constancy of output with varying frequency of ±1 db, with distortion at full power output more than 34 db down on fundamental (less than 2%). On the J1 the output is controlled by a calibrated potentiometer. The output voltage of the J2 is directly monitored by a first grade rectifier voltmeter. The standard models operate from power supplies of 105-125 volts, 210250 volts, A.C. only, 40-100 c/s. The J1/NA and J2/NA operate from power Supplies of 117 volts A.C. only, 25-60 c/s. The J1/E and J2/E operate from power supplies of 110-125 volts, 140-160 volts, and 220 volts A.C. only, 40-100c/s.