Sparton 49 Equasonne

Sparks-Withington Co., (Sparton); Jackson, Michigan

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  • Year
  • 1929/1930
perfect model
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 58638

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

 Technical Specifications

  • Number of Tubes
  • 9
  • Main principle
  • TRF without regeneration; 3 AF stage(s)
  • Tuned circuits
  • 4 AM circuit(s)
  • Wave bands
  • Broadcast only (MW).
  • Power type and voltage
  • Storage and/or dry batteries
  • Loudspeaker
  • - For headphones or amp.
  • Material
  • Wooden case
  • from Radiomuseum.org
  • Model: Sparton 49 Equasonne - Sparks-Withington Co., Sparton
  • Shape
  • Tablemodel, with any shape - general.
  • Notes

  • The Sparton model 49 has one dial (primary tuning control knob) and is from the second generation of Equasonne models. The tubes are the original line up, not replacement, according to the page "The quantity and types of tubes used in Sparton receiving sets" and of Rider's page Sparton 5-6, displacement would be Sparton type 486. The model 39 and (later) model 49 share the same tubes (and schematic). The models 39, 69, 79-A, 89, 89-A, 99, 109 and 930 are the first "Equasonne" models.
    See also the article here about different radio seasons.

    The history to the Equasonne line: In February 1928 RCA sued Sparks-Withington for using the Alexanderson TRF patent. After that, Sparton began using a circuit not covered by that patent, a circuit invented by Lester Jones (Technidyne Corp.). A tube with tightly controlled grid-to-plate capacitances was needed and Sparton-Cardon created the type 484, 485 and 486 and produced them too. Before, Sparton used Kellogg tubes. The Equasonne is a two chassis construction. The RF chassis with 6 tubes used (also?) a phenolic board, not metal. The trick is a 4-circuit pre-selector followed by a broadband amplifier system. Then follows the audio unit with a power-detector (plate detector) with a very high value cathode resistor for a non-linear detector which amplifies.
    The next season followed the Equasonne models 49, 101, 110, 111, 111-A, 301, 301-DC, 931 and 931-DC. The last Equasonne appeared in 1930/31 as models 103, 235, 564, 570, 574, 589, 591, 593, 600, 600-DC, 610, 610-DC, 620, 620-DC, 737, 740, 740-DC, 750, 750-DC, 870.

  • Price in first year of sale
  • 76.00 $
  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)

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