• Country
• United States of America (USA)

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

• Year
• 1947–1949

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

• Radiomuseum.org ID
• 49574

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

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

• Number of Tubes
• 11

• Valves / Tubes
• 6K7 6K7 6J7 6C4 6K7 6K7 6H6 6H6 6SJ7 6V6GT 6J7 0A2

• Main principle
• Superhet with RF-stage; ZF/IF 456 kHz

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

• Power type and voltage
• Powered by external power supply or a main unit. / 115 / 230 Volt

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

• Material
• Metal case

• from Radiomuseum.org
• Model: HRO-7 - National Company; Cambridge &

• Shape
• Boatanchor (heavy military or commercial set >20 kg).

• Dimensions (WHD)
• 19.5 x 10 x 10 inch / 495 x 254 x 254 mm

• Notes

• coverage 0,05 - 30 MHz (9 ganged coil sets 50-100 / 100-200 / 180-430 / 480-960 / 900-2050 kHz / 1,7-4 / 3,5-7,3 / 7-14,4 / 14-30 MHz, bandspread in HAM bands), AM/CW/SSB (BFO);
  new streamlined cabinet, integrated noise limiter, grey micrometer dial and coil sets with linear marks;
  external power supply 697 (voltages: filaments 6,3V B+ 240V), optional external speaker MCR or HRO-7TS.

  The black wrinkle finished version of the HRO 7 is more rare than the smooth gray. It has matching coils, MCR speaker and 697 power supply.

• Net weight (2.2 lb = 1 kg)
• 29.5 kg / 64 lb 15.6 oz (64.978 lb)

• Price in first year of sale
• 279.00 $

• External source of data
• Ernst Erb

• Source of data
• Communications Receivers

• Circuit diagram reference
• Rider's Perpetual, Volume 17 = 1948 and before

• Mentioned in
• Shortwave Receivers - Past & Present (3rd ed.)

• Literature/Schematics (1)
• Allied Catalog 1949 page 11

• Other Models

• Here you find 446 models, 285 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)