General Radio 1390B

The 1390B Random-Noise Generator generates a broad band noise signal (5Hz to 5MHz) with a uniform spectrum level, especially useful in noise and vibration testing of mechanical and electrical systems. Upper frequency cutoff can be set at 20kHz, 500kHz, or 5MHz. Output level is controlled by a 4-step attenuator with 20 dB steps and a continuously variable control providing a calibrated, metered output from <30 ?V to 3 V (depending on filter setting). Audio spectrum level uniformity is rated at ?1 dB. In addition, a 1521B Level Recorder can be attached to give continuous records of level versus frequency.