Duplex Four Type S

McMichael Radio Ltd.; Slough

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  • Year
  • 1932
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 239538
    • alternative name: McMichael, Leslie

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

 Technical Specifications

  • Number of Tubes
  • 4
  • Main principle
  • TRF with regeneration; 2 AF stage(s)
  • Tuned circuits
  • 2 AM circuit(s)
  • Wave bands
  • Broadcast (MW) and Long Wave.
  • Power type and voltage
  • Storage and/or dry batteries
  • Loudspeaker
  • Magnetic loudspeaker (reed) generic.
  • from Radiomuseum.org
  • Model: Duplex Four Type S - McMichael Radio Ltd.; Slough
  • Notes

  • The schematic didn't originally have valves/tubes listed. Other valve/Tube arrangements are likely.
    Volume control varies SG valve (tube) filament and thus gain and is also the on/off push switch. Grid bias by series resistor in HT- so likely a portable set.

    MW is labelled "SW".

    Similar versions (similar TRF, same case, same Bakelite speaker panel moudling)

    The Super Range Portable type A has no tuning scale, just a 0 to 100 logging drum, though the first versions used the fretwork of the Super Screened Portable Four.

    The main differences from the last version Super Range Portable Four type C is the style of tuning scale and removal of the Grid Bias ("C") battery.

    Aug 1934 "Supplement to the Broadcaster" states regarding the 1933 SMC Duplex Four Portable: "The earler models are very similar." The SMC replaces the Triode with a Pentode and "Reed" speaker with a Moving coil.

  • Author
  • Model page created by Michael Watterson. See "Data change" for further contributors.

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