• Country
• Germany

• Manufacturer / Brand
• Dema GmbH; Berlin

• Year
• 1931–1934

• Category
• Detector-Radio (Crystal or diode, without tubes/transistors)

• Radiomuseum.org ID
• 14137

• • alternative name: Marx, A.

• Main principle
• Crystal or Solid State Detector; Crystal-detection 1 circuit (no tubes)

• Tuned circuits
• 1 AM circuit(s)

• Wave bands
• Broadcast (MW) and Long Wave.

• Power type and voltage
• No Power needed

• Loudspeaker
• - For headphones or amp.

• Material
• Wooden case

• from Radiomuseum.org
• Model: Detektor-Empfänger DF7 - Dema GmbH; Berlin

• Notes
• für Steckspulen

• Price in first year of sale
• 3.00 RM

• External source of data
• E. Erb 3-907007-36-0

• Source of data
• Radio-Zentrale Prohaska 1933/34 / Radiokatalog Band 2, Ernst Erb

• Mentioned in
• Katalog Radio-Zentrale Prohaska 1931/32

• Picture reference
• Das Modell ist im «Radiokatalog» (Erb) abgebildet.

• Other Models

• Here you find 7 models, 7 with images and 0 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Dema GmbH; Berlin