The Model SG-83 Standard Signal Generator is a laboratory test instrument which generates accurately known r-f voltages in the 360 kc to 30 me range. Either unmodulated or modulated signals may be obtained. This instrument makes possible for the first time at moderate cost accurate laboratory measurements which are essential in communication circuit development and testing. Because of its accurate output voltage calibration, the SG-83 can be used to make quantitative r-f signal measurements. This signal generator should not be confused with the common signal generator which provides only a source of signals of unspecified level or modulation characteristics. With the SG-83, laboratory measurements may be made which previously required much more expensive industrial equipment not usually available to individuals. The SG-83 signal generator will produce signals of 0.6 microvolt to 16,000 microvolts, accurate to approximately 1 db or + 10%. The output signal is calibrated directly in decibels with zero db equal to one microvolt across a 50 ohm load. Other levels up to -I- 84 db (16,000 microvolts) are obtainable with the switch attenuator and meter. On the front panel of the instrument is a chart to facilitate rapid conversion from microvolts to db and vice versa. The r-f signal is generated by a high-frequency transistor oscillator. The power level of the oscillator is maintained at a level just sufficient to be metered on a panel microammeter to reduce the strength of leakage fields. The transistor r-f oscillator gives excellent frequency stability since there is none of the long warm-up drift common in vacuum tube oscillators. The output is extremely flat over the frequency ranges. Variation in oscillator output over any one band is normally less than 1 db. It is not necessary to readjust the output attenuator continually as the generator is tuned over a wide frequency range, which is a definite convenience in operation. Output from the transistor oscillator is applied to a constant input impedance variable attenuator which is adjusted by a front panel control. The attenuator is designed to produce very little change in loading on the oscillator as the attenuation is varied, to minimize effects on the frequency of the oscillator. The oscillator has a fine tuning control which is useful in varying the frequency in small increments or recalibrating the main tuning dial against an external frequency standard. The fine tuning control is calibrated from + 2.5 to - 2.5 Kc when the main tuning dial is set to 455 Kc. This permits small frequency changes to be read directly when making response curve tests at the commonly used i-f frequency.