• Country
• United States of America (USA)

• Manufacturer / Brand
• Electrical Research Laboratories Inc. (Erla); Chicago, Illinois

• Year
• 1925

• Category
• Radio part (not a module) 

• Radiomuseum.org ID
• 249655

• Wave bands
• - without

• Power type and voltage
• No Power needed

• Loudspeaker
• - - No sound reproduction output.

• Material
• Various materials

• from Radiomuseum.org
• Model: Balloon Circloid RF-Transformer - Electrical Research

• Dimensions (WHD)
• 110 x 110 x 55 mm / 4.3 x 4.3 x 2.2 inch

• Notes

• Toroidal RF-Transformer.

• Other Models

• Here you find 134 models, 47 with images and 61 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Electrical Research Laboratories Inc. (Erla); Chicago, Illinois