HRO Var.4 (according to Moore)

National Company; Cambridge & Malden (MA)

  • Year
  • 1938–1943 ?
  • Category
  • Commercial Receiver (may include amateur bands)
  • Radiomuseum.org ID
  • 86415
    • 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
  • 9
  • 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 180-240 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Power out
  • 1.5 W (unknown quality)
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: HRO [Var.4 ] - 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.

    Bar knobs with metal skirts, S-meter toggle switch, red pilot light left of selectivity control, black bakelite epicyclic dial, usually rectangular IF filter shielding cans.

    External "dog house" type power supply : PSU 697 (filaments 6.3 V AC, B+ 240 V DC) für best performance when mains operated,  5886 (filaments 6,3 V AC, B+ 180 V DC).

    The HRO-B (battery model) is identical, adjusted for maximum performance with a plate voltage (B+) of 180 V. 6,3 Volt D.C. operation with 686S table model of battery power supply with vibrator.

  • Net weight (2.2 lb = 1 kg)
  • 14.5 kg / 31 lb 15 oz (31.938 lb)
  • Price in first year of sale
  • 329.00 $
  • Mentioned in
  • - - Manufacturers Literature
  • Literature/Schematics (1)
  • Electronics Australia November 1990, Page 110
  • Author
  • Model page created by Martin Bösch. See "Data change" for further contributors.

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