• Country
• United States of America (USA)

• Manufacturer / Brand
• Industrial Radio Service; Saginaw, Michigan

• Year
• 1922

• Category
• Broadcast Receiver - or past WW2 Tuner

• Radiomuseum.org ID
• 137914

• Number of Tubes
• 4

• Valves / Tubes
• RAC3 RAC3 RAC3 RAC3

• Main principle
• TRF (Tuned-Radio-Frequency but use of regeneration unknown); Reflex

• Wave bands
• Wave Bands given in the notes.

• Power type and voltage
• Storage and/or dry batteries

• Loudspeaker
• - For headphones or amp.

• Material
• Wooden case

• from Radiomuseum.org
• Model: Baby Ultra 400 - Industrial Radio Service;

• Shape
• Tablemodel, Box - most often with Lid (NOT slant panel).

• Dimensions (WHD)
• 15.5 x 7.5 x 7.5 inch / 394 x 191 x 191 mm

• Notes
• Three stages of RF-amplification, rectification and two stages of AF-amplification employing only four tubes. Operates at full efficiency on wave-length from 150 to 25000 meters by simply inserting proper sets of coils. Employs Myers RAC3 tubes.

• Source of data
• - - Manufacturers Literature

• Mentioned in
• Radio News Dec.1922, p.1178

• Literature/Schematics (1)
• Vintage Radio 1887-1929, Greenwood's Classic Pictorial Album (p.121)

• Literature/Schematics (2)
• Radio Digest Illustrated, 1922 Dec. 02, p. 14

• Author
• Model page created by Otto Frosinn. See "Data change" for further contributors.

• Other Models

• Here you find 9 models, 4 with images and 0 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Industrial Radio Service; Saginaw, Michigan