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HRO-5A1; National Company; (ID = 150806) Commercial Re
HRO-5A1; National Company; (ID = 58374) Commercial Re
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HRO-5A1; National Company; (ID = 58374) Commercial Re
National Company;: HRO-5A1 [Commercial Re] ID = 58374 920x601
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For model HRO-5A1, National Company; Cambridge & Malden (MA)
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 6J7 6V6 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-5A1 - National Company; Cambridge &
Material Metal case
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

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
Source of data Communications Receivers
Circuit diagram reference Rider's Perpetual, Volume 17 = 1948 and before
Mentioned in Shortwave Receivers - Past & Present (3rd ed.)

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.