69. Clayton and Algar, op. cit. (note 11), p. 43.
70. A target to be thrown at, as in a ‘coconut shy’. Glass shards? … What would
‘health and safety’ have to say today!
71. Registered on 20 October 1919. See, W. J. Baker, History of The Marconi
Company 1874–1965, Routledge, (September 1970). ISBN-10:
0415146240, ISBN-13: 978-0415146241.
72. As a result of the formation of the valve group, Robert, Bartlett and other
group members became research staff of the Marconi-Osram Valve Co. Ltd.
at the G.E.C. Research Laboratories. A.C. Bartlett was a highly respected
theoretical physicist and went on to author a number of patents with Robert.
73. In this context, ‘high power’ meant anything from 1 kW to many hundreds
of kW.
74. R. Le Rossignol, E. W. Hall, The Development of Large Radio Transmitting
Valves, GEC Journal, 7, pp. 176–190, (1936).
75. The electrical efficiency of a typical glass valve was at best, about 70%. With
1 kW input (power), 300 watts were ‘wasted’. This energy manifests itself at
the anode plate as heat which has to be dissipated. The greater the power and
the poorer the valve efficiency, the greater is the wasted energy and the need
for efficient heat dissipation.
76. The fundamental techniques being first described by Houskeeper in the
paper; W. G. Houskeeper, The Art of Sealing Base metals through Glass, Trans.
A.I.E.E., 42, pp. 870–876, (June 1923).
77. I am indebted for my understanding here to I.E. Mouromtseff et al., ‘A
review of Demountable vs. Sealed-off Power tubes’, Proceedings of the I.R.E.,
pp. 653–664, (November 1944).
78. The original demountable systems employed mercury condensation pumps
with liquid air traps. This had improved by 1929 when it was found that the
distillation of lubricating oil in a molecular still produced a fraction that was
about a thousand times less volatile than mercury. If such a liquid could be
used as the working fluid in a condensation pump, a vacuum of the order
10
−6 mm (good enough for vacuum tubes) was obtainable without the need
for refrigerants. Later systems therefore employed a two-stage oil diffusion
pump backed up by a rotary pump. But many still felt that this was not an
acceptable part of the equipment of a transmitting radio station. From C.R.
Burch and Dr C. Sykes, ‘Continuously Evacuated Radio Transmitting
Valves’, Nature 135, pp. 262–263, (16 February 1935).
79. Clayton and Algar, op. cit. (note 11), p. 117.
80. Recounted in Chirnside’s Obituary, (Chap. 1) probably from the lecture; ‘A
confidential history’ given by Paterson on the 21st anniversary of the opening
of the ‘new’ laboratories in February 1944, the only speech he ever made
regarding the nature of the laboratory’s work. See also Robert Clayton &
Joan Algar (Editors), A Scientist War. The War Diary of Sir Clifford Paterson,
362
D. Sheppard
70. A target to be thrown at, as in a ‘coconut shy’. Glass shards? … What would
‘health and safety’ have to say today!
71. Registered on 20 October 1919. See, W. J. Baker, History of The Marconi
Company 1874–1965, Routledge, (September 1970). ISBN-10:
0415146240, ISBN-13: 978-0415146241.
72. As a result of the formation of the valve group, Robert, Bartlett and other
group members became research staff of the Marconi-Osram Valve Co. Ltd.
at the G.E.C. Research Laboratories. A.C. Bartlett was a highly respected
theoretical physicist and went on to author a number of patents with Robert.
73. In this context, ‘high power’ meant anything from 1 kW to many hundreds
of kW.
74. R. Le Rossignol, E. W. Hall, The Development of Large Radio Transmitting
Valves, GEC Journal, 7, pp. 176–190, (1936).
75. The electrical efficiency of a typical glass valve was at best, about 70%. With
1 kW input (power), 300 watts were ‘wasted’. This energy manifests itself at
the anode plate as heat which has to be dissipated. The greater the power and
the poorer the valve efficiency, the greater is the wasted energy and the need
for efficient heat dissipation.
76. The fundamental techniques being first described by Houskeeper in the
paper; W. G. Houskeeper, The Art of Sealing Base metals through Glass, Trans.
A.I.E.E., 42, pp. 870–876, (June 1923).
77. I am indebted for my understanding here to I.E. Mouromtseff et al., ‘A
review of Demountable vs. Sealed-off Power tubes’, Proceedings of the I.R.E.,
pp. 653–664, (November 1944).
78. The original demountable systems employed mercury condensation pumps
with liquid air traps. This had improved by 1929 when it was found that the
distillation of lubricating oil in a molecular still produced a fraction that was
about a thousand times less volatile than mercury. If such a liquid could be
used as the working fluid in a condensation pump, a vacuum of the order
10
−6 mm (good enough for vacuum tubes) was obtainable without the need
for refrigerants. Later systems therefore employed a two-stage oil diffusion
pump backed up by a rotary pump. But many still felt that this was not an
acceptable part of the equipment of a transmitting radio station. From C.R.
Burch and Dr C. Sykes, ‘Continuously Evacuated Radio Transmitting
Valves’, Nature 135, pp. 262–263, (16 February 1935).
79. Clayton and Algar, op. cit. (note 11), p. 117.
80. Recounted in Chirnside’s Obituary, (Chap. 1) probably from the lecture; ‘A
confidential history’ given by Paterson on the 21st anniversary of the opening
of the ‘new’ laboratories in February 1944, the only speech he ever made
regarding the nature of the laboratory’s work. See also Robert Clayton &
Joan Algar (Editors), A Scientist War. The War Diary of Sir Clifford Paterson,
362
D. Sheppard