pumping process taking about a day to complete. The M-OV therefore had
banks of pump tables each with an attendant operator. For the much larger
cooled anode valves the pumping process could take as long as a week and
tables were subsequently redesigned to hold a plurality of valves. Photographs
of these ‘modern’ lathes and pumping tables appeared in Robert’s paper of
1936.
16.2.2 CAT Valve Cooling
10
Cooling systems too had to be addressed by the valve group, another
multi-disciplinary area involving chemists and mechanical engineers. It was
here that Robert and Ralph Chirnside (Chap. 18)—who was given an
opportunity to take on the responsibilities of the principal chemical analyst,
W. Singleton, on his death in 1930—collaborated in the evaluation, procurement, preparation and analysis of coolants for valve types used all over the
world, Chirnside eventually becoming GEC’s Chief Chemist in the mid
1950s. CAT valves consisted of an integrated glass envelope and cylindrical
anode enclosing the grid and filament, the leads to which were taken to outlet
points in a further glass cylinder attached to the envelope of the anode and
forming a continuation of it. The valve was mounted perfectly vertically in an
outer jacket, so that the envelope was contained within it but separated from
the walls of the jacket by a space through which the cooling liquid could
circulate. The complete unit was then mounted vertically on insulators,
(using ‘spirit levels’ on the jacket) because the anode and its jacket were at a
potential of thousands of volts above the frame of the transmitter, the filament, and the grid circuits. For water cooled systems, water was taken to and
from the space between the anode envelope and its jacket by means of long
lengths of rubber hose. The purpose of these was to provide a sufficiently long
column of water between the anode and earth to provide a resistance of such
magnitude that it prevented excessive leakage of anode current to earth.
Therefore, with valves of this type it was essential to have water which was as
pure as possible; free from matter suspended or in solution which might
otherwise conduct and/or deposit a layer of ‘scale’ on the envelope inhibiting
the dissipation of heat. Distilled water was therefore generally used, being
continuously circulated through the jacket and then through an external
cooling radiator before being returned. Variations on the water-cooling
method were also designed where the water was allowed to boil away rather
than circulate. These were only feasible when large disposable quantities of
quite pure water were available.
370
D. Sheppard
banks of pump tables each with an attendant operator. For the much larger
cooled anode valves the pumping process could take as long as a week and
tables were subsequently redesigned to hold a plurality of valves. Photographs
of these ‘modern’ lathes and pumping tables appeared in Robert’s paper of
1936.
16.2.2 CAT Valve Cooling
10
Cooling systems too had to be addressed by the valve group, another
multi-disciplinary area involving chemists and mechanical engineers. It was
here that Robert and Ralph Chirnside (Chap. 18)—who was given an
opportunity to take on the responsibilities of the principal chemical analyst,
W. Singleton, on his death in 1930—collaborated in the evaluation, procurement, preparation and analysis of coolants for valve types used all over the
world, Chirnside eventually becoming GEC’s Chief Chemist in the mid
1950s. CAT valves consisted of an integrated glass envelope and cylindrical
anode enclosing the grid and filament, the leads to which were taken to outlet
points in a further glass cylinder attached to the envelope of the anode and
forming a continuation of it. The valve was mounted perfectly vertically in an
outer jacket, so that the envelope was contained within it but separated from
the walls of the jacket by a space through which the cooling liquid could
circulate. The complete unit was then mounted vertically on insulators,
(using ‘spirit levels’ on the jacket) because the anode and its jacket were at a
potential of thousands of volts above the frame of the transmitter, the filament, and the grid circuits. For water cooled systems, water was taken to and
from the space between the anode envelope and its jacket by means of long
lengths of rubber hose. The purpose of these was to provide a sufficiently long
column of water between the anode and earth to provide a resistance of such
magnitude that it prevented excessive leakage of anode current to earth.
Therefore, with valves of this type it was essential to have water which was as
pure as possible; free from matter suspended or in solution which might
otherwise conduct and/or deposit a layer of ‘scale’ on the envelope inhibiting
the dissipation of heat. Distilled water was therefore generally used, being
continuously circulated through the jacket and then through an external
cooling radiator before being returned. Variations on the water-cooling
method were also designed where the water was allowed to boil away rather
than circulate. These were only feasible when large disposable quantities of
quite pure water were available.
370
D. Sheppard