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HRO-M-RR; National Company; (ID = 741427) Commercial Re
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HRO-M-RR; National Company; (ID = 741427) Commercial Re
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Country:  United States of America (USA)
Manufacturer / Brand:  National Company; Cambridge & Malden (MA)
alternative name
National Toy Co.
Year: 1944/1945 Category: Commercial Receiver (may include amateur bands)
Valves / Tubes 9: 6D6 6D6 6C6 6C6 6D6 6D6 6B7 42 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 240 Volt
Loudspeaker - This model requires external speaker(s).
Power out 1.5 W (unknown quality)
from Model: HRO-M-RR - 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

Receiver type HRO-M (no bandspread for Ham bands) supplied for mounting in relay rack.

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, no bandspread in these coils available).

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 Var. 5 with all wave coil sets without bandspread (only one printed calibration chart on coil sets), knobs with metal skirts (selectivity control in right upper corner also with metal skirt), black laquered micrometer dial and round S-meter.

Power supply : Rack variant SPU-697 (filaments 6.3 V AC, B+ 240 V DC) used as standard, "doghouse" type power supply 697 also possible.

Net weight (2.2 lb = 1 kg) 16.5 kg / 36 lb 5.5 oz (36.344 lb)
External source of data Ernst Erb
Source of data Communications Receivers
Circuit diagram reference Rider's Perpetual, Volume 17 = 1948 and before

All listed radios etc. from National Company; Cambridge & Malden (MA)
Here you find 430 models, 275 with images and 163 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.