• Country
• United States of America (USA)

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

• Year
• 1946/1947

• Category
• Commercial Receiver (may include amateur bands)

• Radiomuseum.org ID
• 49571

• • 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 6J7 6K7 6K7 6SQ7 6V6GT 6J7 6J5 6H6

• 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-5TA1 - 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

• Table cabinet version of the latest HRO model HRO-5A1 (HRO Variant 6), with integrated noise limiter (control switch to the left of main tuning), black laquered micrometer dial and round S-meter.

  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, shortwave coils delivered with bandspread in HAM bands).

  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.

  HRO model variant 6 with all knobs with metal skirts (selectivity control in right upper corner and new noise limiter control left of main dial both also with metal skirt), round metal labels around AVC and B+ switches, black micrometer dial and rectangular S-meter, S-meter toggle switch; printed metal calibration charts on coilsets. Rectangular IF filter shielding cans.

  For table model, as standard a "dog house" type power supply PSU 697 (filaments 6.3 V AC, B+ 240 V DC) is used.

• 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 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)