• Country
• United States of America (USA)

• Manufacturer / Brand
• Zenith Radio Corp.; Chicago, IL

• Year
• 1955 ?

• Category
• Medical Technology

• Radiomuseum.org ID
• 121592

• • alternative name: Chicago Radio Lab

Click on the schematic thumbnail to request the schematic as a free document.

• Number of Transistors
• 3

• Semiconductors
• CK718 CK718 CK718

• Main principle
• Audio-Amplification; 3 AF stage(s)

• Wave bands
• - without

• Details
• Hearing aid

• Power type and voltage
• Dry Batteries / 1.5 Volt

• Loudspeaker
• - only for Earphone!

• from Radiomuseum.org
• Model: Royal M Hearing Aid - Zenith Radio Corp.; Chicago,

• Shape
• Very small Portable or Pocket-Set (Handheld) < 8 inch.

• Dimensions (WHD)
• 1.75 x 2.625 x 0.625 inch / 44 x 67 x 16 mm

• Notes

• Wie Zippo-Feuerzeug, in der Front eingearbeitete Telefonspule (zweite Ausführung, weitere Varianten wahrscheinlich).

• Literature/Schematics (1)
• -- Schematic (H.G. Mende, Leitfaden der Transistortechnik, Franzis Verlag München, 1.Auflage 1959 S.217)

• Author
• Model page created by Marc Gianella. See "Data change" for further contributors.

• Other Models

• Here you find 4505 models, 4101 with images and 3631 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Zenith Radio Corp.; Chicago, IL