• Country
• United States of America (USA)

• Manufacturer / Brand
• National Company; Cambridge & Malden (MA)

• Year
• 1964–1973

• Category
• Amateur-Receiver (amateur bands, may include broadcast bands)

• Radiomuseum.org ID
• 74593

• • alternative name: National Toy Co.
  • Brand: Thrillbox

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

• Number of Transistors
• 37

• Semiconductors

• Main principle
• Superhet, double/triple conversion; ZF/IF 2750/230 kHz

• Wave bands
• Broadcast, Long Wave and more than two Short Wave bands.

• Power type and voltage
• Alternating Current supply (AC) / 115 Volt

• Loudspeaker
• - This model requires external speaker(s).

• Material
• Metal case

• from Radiomuseum.org
• Model: HRO-500 - National Company; Cambridge &

• Shape
• Tablemodel, with any shape - general.

• Dimensions (WHD)
• 420 x 195 x 325 mm / 16.5 x 7.7 x 12.8 inch

• Notes

• Coverage 5 kHz - 30 MHz in sixty 500 kHz ranges, built in synthesizer, triple conversion up to 4 MHz, double conversion above 4 MHz; linear analog readout, preselector.

• Net weight (2.2 lb = 1 kg)
• 14.5 kg / 31 lb 15 oz (31.938 lb)

• Source of data
• Shortwave Receivers - Past & Present (3rd ed.)

• Author
• Model page created by Martin Bösch. See "Data change" for further contributors.

• Other Models

• Here you find 445 models, 284 with images and 189 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from National Company; Cambridge & Malden (MA)