Improved SW Booster No. 231

Postal Radio, New York

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  • Year
  • 1935
  • Category
  • RF (Radio Frequency-) Amplifier
  • Radiomuseum.org ID
  • 354578

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

 Technical Specifications

  • Number of Tubes
  • 3
  • Main principle
  • Radio Frequency Amplification only
  • Wave bands
  • Short Wave (SW only)
  • Power type and voltage
  • Alternating Current supply (AC) / 110 Volt
  • Loudspeaker
  • - - No sound reproduction output.
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Improved SW Booster No. 231 - Postal Radio, New York
  • Shape
  • Tablemodel, with any shape - general.
  • Notes

  • The Postal Improved SW Booster No. 231 has the following features:

    • Two-Stage SW TRF Preselector-Booster for TRF or Superheterodyne SW radios.
    • Boosts the tuned SW signal, which is then connected to the SW radio antenna input.
    • SW frequency is tuned with the booster's TRF 2-gang tuning capacitor and tuning coils.  SW Radio should be tuned to the same SW band and frequency as the booster.
    • Front panel SW TRF tuning coils are removable to select the SW bands (assumed the same as the earlier model):
      • "A"   14-29 meters (10.3-21.4 MHz)
      • "B"   29-55 meters (5.4-10.3 MHz)
      • "C"   55-90 meters (3.3-5.4 MHz)
      • "D"   90-200 meters (1.5-3.3 MHz)
    • Powered by 110V AC.
    • Power switch: On / Off.
    • Volume control.
    • Rear terminals: Antenna In +, Antenna In -, GND.
    • Shielded cable pigtail to the SW radio: Antenna Out, GND.
    • Antenna Select switch: Booster On (Antenna In + to booster, booster output to Antenna Out) / Bypass (Antenna In + direct to Antenna Out).

    This model was an improvement over the earlier model for the following reasons:

    • AC power now applied through a power transformer, which isolates AC Line and Neutral/GND from the chassis/GND, eliminating a possible AC shorting issue as described in the earlier model page.
    • Higher B+ voltage to about 200V (from 90V) for greater gain and selectivity.
    • Air vents added to the cabinet sides.

    The earlier model was the Postal Short-Wave Booster.

  • Literature/Schematics (1)
  • -- Original prospect or advert (Short Wave Craft, December 1934, page 476 schematic and description, 491 ad.)
  • Literature/Schematics (2)
  • Radio Craft (January 1935, page 410 schematic and description.)
  • Author
  • Model page created by Jerry Elarton. See "Data change" for further contributors.

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