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HRO Var. 1 (according to Moore)

HRO; National Company; (ID = 1129963) Commercial Re
HRO; National Company; (ID = 1986142) Commercial Re HRO; National Company; (ID = 1986143) Commercial Re
HRO; National Company; (ID = 1986144) Commercial Re HRO; National Company; (ID = 1986145) Commercial Re
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HRO; National Company; (ID = 1986142) Commercial Re
National Company;: HRO [Commercial Re] ID = 1986142 1400x733
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For model HRO Var. 1 (according to Moore), National Company; Cambridge & Malden (MA)
Country:  United States of America (USA)
Manufacturer / Brand:  National Company; Cambridge & Malden (MA)
alternative name
National Toy Co.
Year: 1934/1935 Category: Commercial Receiver (may include amateur bands)
Valves / Tubes 9: 6D6 6D6 6C6 6C6 6D6 6D6 6B7 42 6C6
Main principle Superheterodyne (common); 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 Volt
Loudspeaker - This model requires external speaker(s).
Power out 1.5 W (unknown quality)
from Model: HRO [Var. 1 ] - 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 sold later including long waves ( 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 (instead of round AGS-like knobs in prototype), pearl white S-meter pushbutton switch, no pilot light, white calibration charts with black lettering.

External power supply : PSU 697, 5897 ( when equipped with 2,5 V battery tubes) or 5886 ("dog house" type).

Optional layout for 2.5V heated tubes :

58 58 57 57 58 58 2B7 2A5 57

Net weight (2.2 lb = 1 kg) 14.5 kg / 31 lb 15 oz (31.938 lb)
Price in first year of sale 233.00 USD
External source of data Ernst Erb
Source of data Communications Receivers
Circuit diagram reference Rider's Perpetual, Volume 8 = 1937 and before

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.