• Country
• United States of America (USA)

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

• Year
• 1944/1945

• Category
• Commercial Receiver (may include amateur bands)

• Radiomuseum.org ID
• 49566

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

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

• Number of Tubes
• 9

• Valves / Tubes
• 6K7 6K7 6J7 6J7 6K7 6K7 6SQ7 6V6 6J7

• Main principle
• Superhet with RF-stage; ZF/IF 456 kHz; 2 AF stage(s)

• Tuned circuits
• 11 AM circuit(s)

• 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. / AC 6.3 & DC 240 Volt

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

• Power out
• 1.5 W (unknown quality)

• Material
• Metal case

• from Radiomuseum.org
• Model: HRO-5 - National Company; Cambridge &

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

• Dimensions (WHD)
• 440 x 220 x 300 mm / 17.3 x 8.7 x 11.8 inch

• Notes

• Coverage: 50 kHz - 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, no bandspread in these coils available).

  Modes AM / CW/SSB (BFO).

  The 0 – 500 epicyclic readout dial allows for continuous analog tuning while digitally indicating incremental progress over a range of ten full turns of the large tuning knob that tunes with velvet smoothness. Ten times the circumference of the dial is nearly 4 meters on a normal dial scale, which delivers great frequency resolution. The dial is not calibrated to directly indicate a frequency but a frequency calibration chart is necessary to determine the correct operation frequency.

  Tropicalized HRO model Var. 5 , knobs with metal skirts (selectivity control in right upper corner also with metal skirt), black laquered micrometer dial and round S-meter, on the coil sets on the right a printed chart to register calls / frequencies of specific stations;
  similar to HRO-W (tropicalised) set, built to JAN (joint army-navy) specifications.

  External "dog house" type power supply : PSU 697 (filaments 6.3 V AC, B+ 240 V DC) used as standard.

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

• External source of data
• Ernst Erb

• Source of data
• Communications Receivers

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

• 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)