Note
Service magazine, Aug 1937, p. 489.
Radio's Master Catalog, copyright 1937, p. F-19.
Radio Craft, Oct 1937, inside front cover.
Service magazine, Sep 1938, p. 21.
From the ad:
"Complete with built-in horizontal and vertical amplifiers. Utilizes the full-size 3" screen cathode ray tube. Used for measurements of AC wave forms, frequency, phase, tube characteristics, hysteresis, hum distortion, AC peak volts, overload of AF or IF amplifiers, vibrators, transmitters, etc. Use with RF signal generator for visual alignment work."
"Built-in linear sweep circuit. Synchronizing control holds image on screen stationary. Provisions for internal or external sweep and also for internal or external synchronization. High impedance, low capacitance amplifier circuits give flat frequency amplification to 90,000 Hz. Built-in sweep circuit is linear from 15 to 30,000 Hz, allowing observation of frequencies on the screen up to 300,000 Hz."
References
Technical description. Radio Craft, Jun 1938, p. 805.