Six-Valve Shortwave Superheterodyne

Eddystone (Brand), Stratton and Co., Ltd., Eddystone Radio Ltd.; Birmingham

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  • Year
  • 1935 ?
  • Category
  • Kit (Parts plus instruction) or building instructions only
  • Radiomuseum.org ID
  • 355308

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

 Technical Specifications

  • Number of Tubes
  • 6
  • Number of Transistors
  • Semiconductors
  • WX6
  • Main principle
  • Superheterodyne (common)
  • Wave bands
  • Short Wave (SW only)
  • Power type and voltage
  • Alternating Current supply (AC)
  • Loudspeaker
  • Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
  • Material
  • Metal case, TUBES VISIBLE
  • from Radiomuseum.org
  • Model: Six-Valve Shortwave Superheterodyne - Eddystone Brand, Stratton and
  • Shape
  • Chassis only or for «building in»
  • Notes

  • Six-Valve Shortwave Superheterodyne Kitset: Detailed Breakdown

    This kitset offers a complete shortwave radio experience, featuring:

    • Six Valves: This includes a full-wave rectifier for power conversion and a metal rectifier for automatic volume control (AVC).
    • Superheterodyne Design: It employs the superheterodyne principle, converting received signals to a fixed intermediate frequency (IF) for easier amplification and filtering.

    Signal Processing Stages:

    • First Detector: A screened-grid valve functions as an anode-bend rectifier, converting the received radio signal to an IF signal.
    • Local Oscillator: A separate triode valve generates the necessary oscillation signal for frequency mixing in the superheterodyne process.
    • Intermediate Frequency (IF) Amplifier: A variable-mu-screened pentode amplifies the IF signal at a fixed frequency of 450 kHz.
    • Second Detector: A screened high-frequency pentode with power grid rectification demodulates the IF signal to recover the audio information. This stage uses resistance coupling to connect to the output valve.
    • Output Stage: A directly heated pentode valve provides power amplification for the audio signal.

    Tuning and Controls:

    • Ganged Tuning: A ganged capacitor simplifies tuning by adjusting both the antenna circuit and oscillator simultaneously across four-wave ranges. A small trimmer capacitor fine-tunes the antenna circuit for optimal reception.
    • Four Wave Ranges: The switchable wave ranges cover a broad spectrum from 13 to 68 metres, approximately 21.4 to 4.4 MHz.
    • Automatic Volume Control (AVC): An AVC circuit with a dedicated metal rectifier (WX6) automatically adjusts the gain to maintain consistent audio volume even with varying signal strengths. A switch allows you to bypass the AVC and use a manual volume control for more precise adjustments.

    Construction Details:

    • Robust Chassis: The receiver, including the power supply, is built on a sturdy cast aluminum alloy chassis, providing a reliable foundation for assembly.
    • Effective Shielding: The coil unit utilizes a one-piece metal casting to shield the oscillator circuit, minimizing unwanted signal interactions (interlocking).
    • High-Quality Transformer: The mains transformer is designed for exceptional performance, ensuring good voltage regulation without overheating.

    Further Information:

    This kitset was comprehensively described in Eddystone Shortwave Manual No. 2 (1935), on pages 34-38.

  • Mentioned in
  • - - Manufacturers Literature (Eddystone Shortwave Manual No. 2 1935, Pages 34 - 38)
  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

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