General. The Sprague Model 600A interference Locator is a rugged, wide-range, portable instrument designed especially to meet the needs of electric utilities, laboratories, industries and others concerned with the detection and location of sources of r-f transmissions and interference. Special attention has been given to the design details which contribute to the reliability and convenience of use. 1.2 Operating Frequency and Sensitivity. The Model 600A Interference Locator covers from 540 kHz to 220 MHz in six tuning ranges with a sensitivity of 2 microvolts or better at all frequencies, for a 5% output meter deflection. 1.3 Application. The Model 600A interference Locator is designed for the rapid detection and location of AM/FM radio and TV signal sources. Other effective uses include the following: a. Location of communications interference sources (corona noise, power line leaks) by electric utilities. b. Maintenance programs, both preventive and otherwise, since many faults will begin to radiate r-f noise before actual failure occurs. c. Laboratory and other testing and investigative applications. The instrument is useful as an r-f null detector or voltmeter when so calibrated. d. Direction finding in marine applications. e. Detection and location of sources of r-f transmissions within the frequency range of the instrument.