HRO-5A1

National Company; Cambridge & Malden (MA)

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  • Year
  • 1946/1947
  • Category
  • Commercial Receiver (may include amateur bands)
  • Radiomuseum.org ID
  • 49569
    • alternative name: National Toy Co.
    • Brand: Thrillbox

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

 Technical Specifications

  • Number of Tubes
  • 11
  • 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-5A1 - 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 : 1.7 – 30 MHz ( 4 standard ganged coil sets for 1.7 – 4, 3.5 – 7.3, 7 – 14.4, 14 – 30 MHz included, 2 coil sets for broadcast immediately available at extra cost, 7 more coil sets Additional coils (50-100, 100-200, 180-430, 480-960 and 900-2050 kHz) sold later including long waves and up to VHF ( total spectrum covered from 50 kHz to 54 MHz ).

    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.

    The latest HRO model (Var. 6) was sold as HRO-5A1, 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.

    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)
  • Price in first year of sale
  • 274.00 $
  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 17 = 1948 and before

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