“Nevertheless, for a considerable time, it has been possible to buy a special type of receiver which practically fulfils the ideal specifiaction for a portable receiver. It eliminates all interference, save atmospheric discharges which are still uncurable, but, fortunately, innocuous on most winter and some summer evenings.
“It will operate a powerful loudspeaker at full strength without an outside aerial or real earth, requiring no pick-up inductance beyond a small frame aerial, which may be of the folding type or can be wound inside the lid of a cabinet. Its current consumption is so small that a tiny four-volt accumulator [that’s a battery to you and me] of 20Ah capacity will operate it for 50 or 60 hours on one charge. It has controls so few and so simple that a wholly untechnical woman [or man, come on BH…] in Great Britain can pick up American broadcast programmes with it.”
The reason we had to put up with inferior wireless until this time was, apparently, due to the lack of dull emitter valves. Probably won’t find any of those in your DAB radio.
The one and only drawback of the ‘supersonic heterodyne’ (brilliant name) receiver was – as has always been and always will be the case with new technologies – price. A ready-made receiver would’ve cost you £75 (the equivalent of about £4480 today).
However, most people back then would have constructed their own sets, thanks to instructions provided by specialist magazines, and the principle of a ‘superhet’ was “childishly simple”.
“If two stations are broadcating telephony on neighbouring wavelengths,” Davies laid out, “ordinary methods of reproduction will fail to separate the two stations, especially if they are of equal power and equidistant from the listener. But if these two wavelengths are multiplied by some high figure, the margin between them will no longer be narrow, but they can be sundered so completely that the desired signals can be thoroughly isolated with extreme purity.
“This is readily achieved by the superhet. A rough and inaccurate description would say that the signals are rectified, transferred to a tremendously higher wavelength, amplified on that new wavelength and finally listened to with the aid of a loudspeaker.”
This technique usually required as many as 10 valves, but the superhet could use just five, making several work double jobs. Indeed, wireless technology was progressing at an incredible rate. “This year, the upkeep of a superhet will be less than the yearly bill of a humble headphone two-valver of the 1924 pattern,” predicted Davies.
“The newer version rescues the garden from towering masts; and in winter it has the second merit of permitting the owner to enjoy his news or his symphonies in whichever room is most convenient.