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Country:  United States of America (USA)
Manufacturer / Brand:  National Company; Cambridge & Malden (MA)
alternative name
National Toy Co.
Year: 1946/1947 Category: Commercial Receiver (may include amateur bands)
Valves / Tubes 11: 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)
from Model: HRO-5RA-1 - National Company; Cambridge &
Material Metal case
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

Rack 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.

Rack type power supply SPU-697 as standard, can also be operated from  "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) 16.5 kg / 36 lb 5.5 oz (36.344 lb)
Source of data Communications Receivers

Model page created by Martin Bösch. See "Data change" for further contributors.

All listed radios etc. from National Company; Cambridge & Malden (MA)
Here you find 430 models, 275 with images and 162 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.