Philips 'superinductance' broadcast receiver type 634A, 1933. This model is one of a series of receivers in which the Philips company achieved, with tuned radio-frequency circuits, a selectivity and range equal to that of contemporary superheterodyne receivers. The term ‘superinductance’ refers to the tuning coils, Litz-wound on glass formers whose efficiency was largely responsible for the success of the design.
The receiver employs two variable-mu high-frequency amplifiers, preceded by a band-pass input circuit, and followed by a diode-tetrode detector/amplifier and a pentode output valve. The tuning knob controls four carefully aligned capacitors, and also a potentiometer which varies the bias on the high-frequency valves, to maintain constant sensitivity over the waveband.
- Radio Communication
- Object Number:
- Combined Electronic Services Ltd.