Majestic Ch= 300 Twin Speaker

Grigsby-Grunow (-Hinds) Co. (Majestic pre 1933); Chicago (IL)

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  • Year
  • 1932/1933
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 43625

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

 Technical Specifications

  • Number of Tubes
  • 11
  • Main principle
  • Superhet with RF-stage; ZF/IF 175 kHz
  • Tuned circuits
  • 7 AM circuit(s)
  • Wave bands
  • Broadcast only (MW).
  • Power type and voltage
  • Alternating Current supply (AC) / 117 Volt
  • Loudspeaker
  • Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Majestic Ch= 300 Twin Speaker - Grigsby-Grunow -Hinds Co.
  • Shape
  • Chassis only or for «building in»
  • Notes
  • The series 300 models are fitted either with a large G-14-F speaker or have twin speaker G-19-B and G-19-C. Grigsby-Grunow uses here the first time their "Automatic Synchro-Silent Tuning", variing a tuning light by a reactor with 3 legs of iron core. Two legs are connected in series with the pilot light, while the winding on the center leg is connected in series with the plates of the RF First Detector, and IF tubes. An electrolytic condenser (C-5) shunts the center winding for not getting any AC if there are unbalances. They call the system also "Reactance Resonance Indicator". When a station is tuned in, an automatic bias voltage is built across Resistor R-9, causing the pilot light to dim.
  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 3 = 1933 and before
  • Mentioned in
  • Rider's Changes 7-11

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