these devices, especially for transmitting purposes. In terms of radio communication lamp technology was still of considerable value, especially for
small receiving valves, but the development of large high powered
73 transmitting valves presented major new interdisciplinary problems; problems
which crossed the boundaries of mathematics, chemistry, physics, and electrical engineering, at the same time generating new disciplines such as statistical testing and materials science. Making sense of Robert’s efforts here
demands at least some understanding of ‘thermionic’ technology and interested readers are referred to Appendix E for a very basic grounding, but
undoubtedly the eclectic nature of the discipline of thermionic technology
was what motivated Robert to move from lamps to valves. This progression
can be seen by the nature of the patents he filed during the decade, sometimes
with others. Four patents were filed on behalf of the GEC between 30
October 1924 and 17 November 1926. viz, ‘Improvements in electric discharge tubes’, ‘Improvements in thermionic valves’, ‘Improvements in or
relating to the construction of electric discharge tubes’, and ‘Thermionic
Valve’. (see Appendix F) By the mid 1930s, the GEC valve team had
developed some of the most powerful radio transmitting valves in the world,
developments with which Robert was closely associated and which he
chronicled in a substantial paper in 1936.
74 We develop this aspect of his life
more fully in the next chapter. However, when the Wembley valve team was
formed, transmitting valves were then quite different.
15.6.1 Improvements in Early Transmitting Valves
At the end of the first world war, the largest commercially available wireless
transmitting valves, the so-called ‘glass’ valves, were capable of dealing with an
input of just 1 kilowatt (kW). Bearing in mind that the efficiency of a valve
was seldom more that 70% and often no more than 30%, it was necessary to
parallel a great number of them to achieve a high-power amplification. But
with regard to improvements in amplification, the glass valve suffered from a
number of deficiencies.
The anode dissipation
75 of a typical glass transmitting valve at the end of
the war was around 300 watts, and a major problem confronting the development of more powerful valves was the requirement that the temperature of
the glass should not exceed *200 °C, otherwise gas would be evolved
causing the vacuum to deteriorate and the grid to lose its control over the
valve’s characteristics. Therefore, to build a more powerful valve with a much
larger anode dissipation, the glass bulb had to increase in surface area to allow
350
D. Sheppard
small receiving valves, but the development of large high powered
73 transmitting valves presented major new interdisciplinary problems; problems
which crossed the boundaries of mathematics, chemistry, physics, and electrical engineering, at the same time generating new disciplines such as statistical testing and materials science. Making sense of Robert’s efforts here
demands at least some understanding of ‘thermionic’ technology and interested readers are referred to Appendix E for a very basic grounding, but
undoubtedly the eclectic nature of the discipline of thermionic technology
was what motivated Robert to move from lamps to valves. This progression
can be seen by the nature of the patents he filed during the decade, sometimes
with others. Four patents were filed on behalf of the GEC between 30
October 1924 and 17 November 1926. viz, ‘Improvements in electric discharge tubes’, ‘Improvements in thermionic valves’, ‘Improvements in or
relating to the construction of electric discharge tubes’, and ‘Thermionic
Valve’. (see Appendix F) By the mid 1930s, the GEC valve team had
developed some of the most powerful radio transmitting valves in the world,
developments with which Robert was closely associated and which he
chronicled in a substantial paper in 1936.
74 We develop this aspect of his life
more fully in the next chapter. However, when the Wembley valve team was
formed, transmitting valves were then quite different.
15.6.1 Improvements in Early Transmitting Valves
At the end of the first world war, the largest commercially available wireless
transmitting valves, the so-called ‘glass’ valves, were capable of dealing with an
input of just 1 kilowatt (kW). Bearing in mind that the efficiency of a valve
was seldom more that 70% and often no more than 30%, it was necessary to
parallel a great number of them to achieve a high-power amplification. But
with regard to improvements in amplification, the glass valve suffered from a
number of deficiencies.
The anode dissipation
75 of a typical glass transmitting valve at the end of
the war was around 300 watts, and a major problem confronting the development of more powerful valves was the requirement that the temperature of
the glass should not exceed *200 °C, otherwise gas would be evolved
causing the vacuum to deteriorate and the grid to lose its control over the
valve’s characteristics. Therefore, to build a more powerful valve with a much
larger anode dissipation, the glass bulb had to increase in surface area to allow
350
D. Sheppard