Signedunder central dial: Beat-Frequency Oscillator / Type 713-B Serial No. 735 / General Radio Co. / Cambridge Mass. U.S.A.
Inscribedon a plaque, riveted on wood frame: THIS INSTRUMENT IS LICENSED UNDER PATENTS OF THE AMERICAN TELEPHONE AND TELEGRAPH COMPANY SOLELY FOR UTILIZATION IN RESEARCH, INVESTIGATION, MEASUREMENT, TESTING, INSTRUCTION AND DEVELOPMENT WORK IN PURE AND APPLIED SCIENCE.
in yellow paint: PHYSICS DEPT.
FunctionAccording to the instruction manual: "The Type 713-B Beat-Frequency Oscillator is an a-c operated device intended for use as a source of alternating current for making tests in the audio-frequency and lower supersonic-frequency ranges. The frequency range of the oscillator is from 10 to 40,000 cycles per second with a logarithmic calibration from 20 to 20,000 cycles per second...
[F]or most practical audio-frequency tests, it is merely necessary to connect the oscillator directly to the line or equipment, making sure that a reasonable impedance match is secured, and then turn the main frequency control over the audio-frequency range and note the reading of an output meter on the equipment under test."
The company claimed that this oscillator would provide high output with low harmonic distortion.
Primary SourcesGeneral Radio Co., Operating Instructions for Type 713-B Beat-Frequency Oscillator (Cambridge, MA, ca. 1935).
ProvenanceCame from the Physics Department of Bowdoin College.
Related WorksSee the GR Historical Society Website: www.teradyne.com/corp/grhs