Bell 1A / 1A1 amp module KS-14990

Western Electric Company Inc.; New York (NY)

  • Year
  • 1954
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 222520

 Technical Specifications

  • Number of Tubes
  • 4
  • Main principle
  • Audio-Amplification
  • Wave bands
  • - without
  • Power type and voltage
  • Powered by external power supply or a main unit.
  • Loudspeaker
  • - This model requires external speaker(s).
  • from Radiomuseum.org
  • Model: Bell 1A / 1A1 amp module KS-14990 - Western Electric Company Inc.;
  • Shape
  • Chassis only or for «building in»
  • Dimensions (WHD)
  • 3.5 x 2.1 x 3.5 inch / 89 x 53 x 89 mm
  • Notes
  • Printed circuit board consists of two identical, 2-tube (3V4 and Raytheon CK512AX) amplifiers. It is used in Western Electric 1A and 1A1 speakerphone systems. It appears that one amplifier is used to amplify the dynamic microphone signal, the other to drive the moving coil permanent magnet speaker. Both amplifiers have a 1 Megohm potentiometer (each with a slot ended shaft) mounted on a common metal bracket on the side of the board opposite the 15 conductor card edge connector. Each amplifier has only one capacitor (apparently mica) located under the potentiometers. The amplifier plugs into a control unit (the 1A Speakerphone uses a KS 14964 or KS 14964 L2 control unit; the 1A1 Speakerphone uses a KS 14964 L3 or KS 16162 L2 control unit). The control unit runs on 120VAC power and provides the lower voltage filament and higher voltage power supplies to the KS-14990. All tubes plug into sockets. The Raytheon CK512AX subminiature tubes are held in place with spring retainer brackets.
  • Net weight (2.2 lb = 1 kg)
  • 0.4 lb (0 lb 6.4 oz) / 0.182 kg
  • Source of data
  • - - Manufacturers Literature
  • Author
  • Model page created by Gary Brandenburger. See "Data change" for further contributors.

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