HRO Var. 6 (according to Moore)

• alternative name: National Toy Co.
• Brand: Thrillbox

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.

HRO-model with 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.

This model variant has been used for HRO-5A1 sets.

In questo link sono elencati 445 modelli, di cui 284 con immagini e 189 con schemi.
Elenco delle radio e altri apparecchi della National Company; Cambridge & Malden (MA)