• Country
• United States of America (USA)

• Manufacturer / Brand
• Radio Shack (Tandy, Realistic, Micronta); USA

• Year
• 1977

• Category
• Kit (Parts plus instruction) or building instructions only

• Radiomuseum.org ID
• 336046

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

• Number of Transistors
• 1

• Semiconductors
• 2N2484

• Main principle
• Crystal or Solid State Detector with Amplifer

• Wave bands
• Wave Bands given in the notes.

• Power type and voltage
• Dry Batteries / AA: 1 x 1.5 Volt

• Loudspeaker
• - - No sound reproduction output.

• from Radiomuseum.org
• Model: Science Fair Field Strength Meter in a P-box 28-139 - Radio Shack Tandy, Realistic,

• Dimensions (WHD)
• 5.25 x 2.5 x 4.5 inch / 133 x 64 x 114 mm

• Notes

• Field strength meter 28-139 is equipped with high-sensitivity transistor amplifier. Works with CB and other transmitters.  The circuit consists of two untuned crystal detectors amplified by one transistor and fed to a 150 microamp meter.  Sensitivity is adjustable.

  The 28-139 is one of a number of inexpensive Radio Shack kits built on a plastic chassis called a "P-box".

   

• Price in first year of sale
• 6.95 US$

• Mentioned in
• Radio Shack catalog 1977 (new)

• Literature/Schematics (1)
• kit instruction pamphlet has schematic

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

• Other Models

• Here you find 1299 models, 1181 with images and 117 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Radio Shack (Tandy, Realistic, Micronta); USA