Natural Philosophy Collection

The Tuning Condenser

The wireless has played an important cultural rôle in twentieth century society. I am thinking of a real wireless, a piece of mahogany-verneer furniture with a glass dial on which were printed the once familiar names Athlone, London, Third, Light, Welsh, Scottish and the more international Hilversum, Paris, Brussels, Lyons, Vienna, and more besides. Behind the dial, a travelling pointer illuminated by two small bulbs could be swept around to tune in to whatever stations chance and atmospheric conditions could bring within the grasp of the long wire aerial. When your fingers turned the tuning knob they turned, via some well-greased epi-cyclic gearing or a spring-tensioned string and drum mechanism, a wonderful device called the tuning condenser. It usually had three gangs of closely spaced vanes, weighed up to half a kilo and reminded everyone of an egg-slicer. It can rightly be considered the electronic component symbolic of the wireless age. The example in our picture was designed for lower electrical loss, higher voltage and smaller range than that found in the domestic radio receiver. The curved vanes have been calculated to give straight-line tuning across the dial. It combines the fitness of purpose of the best in engineering with an artistic shape worthy of a pedestal in a modern gallery. Hand assembled from mass produced parts of aluminium, ceramic, brass and steel, this variable capacitor, to give it its more general name, will work as well in a hundred years time as it did when it was made, probably some forty years ago. Its light, open form, its variable aspect and its slicing of space are delights in themselves and, for the knowledgeable, symbolic of its rôle in slicing the radio spectrum into separate stations.

John S. Reid