HRO Senior HRO-SR

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

After introduction of the HRO Junior the original fully featured HRO ( with crystal filter, S-meter, 4 coil sets and bandspread ) was referenced retroactively as HRO Senior.

This is not a special model, only the testimony of an additional suffix given in order to distinguish it from the HRO Junior.

See different HRO model variants  ( Var. 1 - Var. 6 )

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, so more used as logging dial, the frequency is determined used printed calibration charts on coil sets.

External "dog house" power supplies used : 5886 (B+ 180V), PSU 697 (B+ 240V) or 5897 (filaments 2,5V AC, B+ 230V DC) for sets equipped with battery valves set.

In questo link sono elencati 446 modelli, di cui 285 con immagini e 189 con schemi.
Elenco delle radio e altri apparecchi della National Company; Cambridge & Malden (MA)