HRO-M-RR

National Company; Cambridge & Malden (MA)

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  • Year
  • 1944/1945
  • Category
  • Commercial Receiver (may include amateur bands)
  • Radiomuseum.org ID
  • 49576
    • 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 240 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Power out
  • 1.5 W (unknown quality)
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: HRO-M-RR - National Company; Cambridge &
  • Shape
  • Boatanchor (heavy military or commercial set >20 kg).
  • Dimensions (WHD)
  • 480 x 260 x 300 mm / 18.9 x 10.2 x 11.8 inch
  • Notes

  • Receiver type HRO-M (no bandspread for Ham bands) supplied for mounting in relay rack.

    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.

    HRO model Var. 5 with all wave coil sets without bandspread (only one printed calibration chart on coil sets), knobs with metal skirts (selectivity control in right upper corner also with metal skirt), black laquered micrometer dial and round S-meter.

    Power supply : Rack variant SPU-697 (filaments 6.3 V AC, B+ 240 V DC) used as standard, "doghouse" type power supply 697 also possible.

  • Net weight (2.2 lb = 1 kg)
  • 16.5 kg / 36 lb 5.5 oz (36.344 lb)
  • External source of data
  • Ernst Erb
  • Circuit diagram reference
  • Rider's Perpetual, Volume 17 = 1948 and before

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