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Crossroads of Technology

A C Wyatt BSc FIP3, The Valve Museum, March, 2022.
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Sputnik-1 October 1957.

The writer recently acquired the May 1957 edition of The Radio Constructor with the aim of reproducing the article on the ECL80 Amplifier. However, the issue also contained two superhet receiver designs - A valve battery portable and a transistor portable. An interesting juxtaposition of the current and future direction of electronics technology.

An exploded view of the first artificial satellite.

Sputnik-1 launched in October an opened the era of space exploration. The signals received from this 60 cm sphere transfixed the world. Exotic technology was imagined by the public but the one watt transmitters used reliable valves with flying leads and convention HF circuitry.

Circuit of one transmitter.

Back on earth the advent of available transistors gave rise to a complete rethink of equipment construction. Sargrove anticipated the move away from conventional chassis construction with the ECME automatic production line in 1947. Home construction, and almost all industrial manufacture of consumer equipment relied on the traditional metal chassis. A firm chassis was essential with heavy transformers and large components.

The 'Rambler' portable superhet.

The valve superhet in the May 1957 magazine uses both a metal chassis and a strong wooden case - HT batteries were heavy (and expensive).

The transistor based receiver uses an insulating sheet as the substrate and suggests Paxolin (opaque) or Perspex (Clear) as the base upon which to construct the set.

Internal view of the transistor superhet.

Looking at the picture above shows that the passive components are identical to those used in the valve set. Only later would the low voltage world of the transistor be supplied with small components with low working voltages. Progress in materials science was rapid the the following years as the massive cost of space launches demanded ever more miniature components.

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