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HRO Var. 3 (according to Moore)

HRO; National Company; (ID = 754300) Commercial Re HRO; National Company; (ID = 754301) Commercial Re
HRO; National Company; (ID = 754304) Commercial Re HRO; National Company; (ID = 754306) Commercial Re
HRO; National Company; (ID = 754307) Commercial Re HRO; National Company; (ID = 754308) Commercial Re
HRO; National Company; (ID = 754309) Commercial Re HRO; National Company; (ID = 754310) Commercial Re
HRO; National Company; (ID = 1984966) Commercial Re HRO; National Company; (ID = 1984967) Commercial Re
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HRO; National Company; (ID = 754300) Commercial Re
National Company;: HRO [Commercial Re] ID = 754300 933x440
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For model HRO Var. 3 (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: 1936–1938 ? Category: Commercial Receiver (may include amateur bands)
Valves / Tubes 9: 6D6 6D6 6C6 6D6 6D6 6B7 42 6C6 6C6
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 180 Volt
Loudspeaker - This model requires external speaker(s).
Power out 1.5 W (unknown quality)
from Model: HRO [Var. 3 ] - National Company; Cambridge &
Material Metal case
Shape Boatanchor (heavy military or commercial set).
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, S-meter toggle switch, pilot light left of selectivity control, engraved panel markings for B+, AVC and Selecctivity, metal look dial knob, black colourted chassis and round IF transformers.

External power supply : PSU 697 or standard 5886 ("dog house" type).


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
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.