• Country
• United States of America (USA)

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

• Year
• 1949/1950

• Category
• Amateur-Receiver (amateur bands, may include broadcast bands)

• Radiomuseum.org ID
• 49640

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

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

• Number of Tubes
• 17

• Valves / Tubes
• 6BA6 6BA6 6BE6 6C4 6K7 6K7 6J7 6H6 6SN7GT 6H6 6SJ7 6V6GT 6V6GT 6AK6 6SK7 6H6 5U4G 0B2

• Main principle
• Superhet with RF-stage; ZF/IF 455 kHz

• Wave bands
• Broadcast, Long Wave and more than two Short Wave bands.

• Power type and voltage
• Alternating Current supply (AC) / 110-120; 220-240 Volt

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

• Power out
• 8 W (unknown quality)

• Material
• Metal case

• from Radiomuseum.org
• Model: HRO-50T - National Company; Cambridge &

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

• Dimensions (WHD)
• 501 x 257 x 420 mm / 19.7 x 10.1 x 16.5 inch

• Notes

• The National HRO-50 family are AC operated multi-band communications receivers. 

  Note that any reference to "HRO-50" and the updated "HRO-50-1" models are generic and not actual models offered for sale.

  Features include:

  • Bands: 0.05 - 30 MHz (9 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),
  • Bandspread in HAM bands,
  • AM/CW/SSB (BFO),
  • First HRO model with internal power supply,
  • Headphone jack on front panel,
  • Optional external speaker HRO-50TS for table models or HRO-50RS for rack models,
  • Optional crystal calibrator unit XCU for original T/R models or XCU-50-2 for updated T1/R1 models,
  • Optional narrow band-FM adaptor NFM-50,
  • Optional 650S 6V-vibrator pack, and
  • Select-O-Ject notch filter SOJ-3.

  The family models are:

  Model	Table/Rack Mount	Tubes
  HRO-50T	Table	17
  HRO-50R	Rack Mount	17
  HRO-50T1	Table	15
  HRO-50R1	Rack Mount	15

  See also R-460/UR version for US Coast Guard.

• Net weight (2.2 lb = 1 kg)
• 43 kg / 94 lb 11.4 oz (94.714 lb)

• Price in first year of sale
• 335.00 USD

• External source of data
• Ernst Erb

• Source of data
• Communications Receivers

• Circuit diagram reference
• Rider's Perpetual, Volume 21, Copyright 1950

• Literature/Schematics (1)
• Photofact Folder, Howard W. SAMS (Set 112, Folder 7, Nov. 1950.)

• Literature/Schematics (2)
• Shortwave Receivers - Past & Present (4th ed.) (page 485.)

• 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)