• Country
• United States of America (USA)

• Manufacturer / Brand
• Johnson Company, E.F.; Waseca, MN

• Year
• 1957

• Category
• Amateur Equipment (Other, but not Key)

• Radiomuseum.org ID
• 335897

• • Brand: Viking

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

• Number of Tubes
• 2

• Valves / Tubes
• 12AX7 12AU7

• Main principle
• Audio-Amplification

• Wave bands
• - without

• Power type and voltage
• Powered by external power supply or a main unit. / 450 DC and 6.3 AC Volt

• Loudspeaker
• - - No sound reproduction output.

• Material
• Metal case, TUBES VISIBLE

• from Radiomuseum.org
• Model: Speech Amplifier-Modulator 250-40 - Johnson Company, E.F.; Waseca,

• Shape
• Chassis only or for «building in»

• Dimensions (WHD)
• 4.1875 x 4.75 x 4 inch / 106 x 121 x 102 mm

• Notes

• This amplifier/ screen modulator provides phone operation for the Johnson Viking Adventurer amateur transmitter.  It is high gain and may be used with either a crystal or dynamic microphone.  Power is taken from the transmitter.  Power and hook-up details are in the schematic. The chassis is designed to plug directly into the accessory socket of the Adventurer.

• Price in first year of sale
• 12.25 USD

• Mentioned in
• 1957 Johnson catalog

• Author
• Model page created by Rich Post. See "Data change" for further contributors.

• Other Models

• Here you find 66 models, 56 with images and 29 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Johnson Company, E.F.; Waseca, MN