MB-29

National Company; Cambridge & Malden (MA)

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  • Year
  • 1929
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 49579
    • alternative name: National Toy Co.
    • Brand: Thrillbox

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

 Technical Specifications

  • Number of Tubes
  • 9
  • Main principle
  • TRF (Tuned-Radio-Frequency but use of regeneration unknown); 2 AF stage(s); Screengrid 1926-1935
  • Tuned circuits
  • 4 AM circuit(s)
  • Wave bands
  • Broadcast only (MW).
  • Power type and voltage
  • Alternating Current supply (AC) / 115 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: MB-29 - National Company; Cambridge &
  • Shape
  • Chassis only or for «building in»
  • Dimensions (WHD)
  • 18 x 0 x 13.5 inch / 457 x 0 x 343 mm
  • Notes
  • The MB-29 has one dial (primary tuning control knob). We can imagine that the MB-29 itself has only 4 tubes: 224, 224, 224 and 227 - like the follower, MB-29A for which we have the following information: The MB-29A four stage tuner in a frosted aluminium chassis is for mounting in a console or with electric phonograph combination. There is no rectifier tube mentioned. It is recommended to use it together with the National "245" push-pull amplifier - which has also a field supply for a dynamic speaker.
  • Price in first year of sale
  • 80.00 $
  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)
  • Literature/Schematics (1)
  • Chicago Salvage Stock Store catalogue, 1928?
  • Literature/Schematics (2)
  • -- Schematic (La Riparazione degli Apparecchi Radio, Delforno - Colciago, Italy 1941)

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