Ferranti

Ferranti grew out of Sebastian Ziani de Ferranti's electrical engineering work. His first company dates from 1882, and in 1896 he moved its operations to Hollinwood near Oldham. Transformers and power equipment came before radio; by the 1930s the company also made receivers. For its own superheterodyne sets it chose to design specific tubes rather than adapt the circuits to existing types. In 1933 it began designing and manufacturing tubes at Hollinwood, offering them both as replacements and to independent constructors. The VHT4, an indirectly heated heptode rated at 4 volts and 1 ampere, combined oscillator and first detector functions for frequency conversion. Contemporary technical press presented it as the first British heptode for superheterodyne receivers.

Ferranti's tube work was not confined to the VHT4. Its 1930s range included other receiver types, while the group's facilities expanded from Hollinwood to Moston and later to Gem Mill near Oldham, Edinburgh and Dundee. These were group sites with different roles and periods. Direct tube manufacture is clearly documented at Hollinwood, and not every tube subsequently sold under the Ferranti name was made by the company. From 1939 the catalogue expanded with types derived from American series and later Mullard's E series, but many were manufactured elsewhere. Ferranti Inc. is also recorded in New York around 1930 at 130 West 42nd Street: this was an American commercial presence, not evidence that British Ferranti tubes were made in the United States.

The Ferranti name continued through different kinds of equipment. During the Second World War the company made naval radar, gyroscopic gunsights and IFF systems; defence, communications and computing grew after the war. In 1951 the Ferranti Mark 1 was built at Moston as a commercial version of the University of Manchester's computer project. Its logic gates used tubes and its main memory employed a cathode-ray tube, with a magnetic drum providing slower storage. Building the computer at Moston does not mean that all its tubes came from that factory. Ferranti merged with International Signal and Control in 1987; it entered receivership in 1993 and its remaining businesses were broken up. To attribute a Ferranti tube correctly, its type, period and evidence of manufacture matter as much as the name printed on the glass or box.