The AUDION,
or three-electrode valve – triode -, invented by Lee
de Forest in 1907, was the most flexible electronic component
until the invention of the Transistor in 1948. The manufacturing
of a thermionic valve requires many types of materials as
well as involves several production stages based in a technology
developed in researches started in 1913. Thus, CLAUDE
PAILLARD a French radio amateur, call F2FO, and a deeply
involved in the researche in the history of thermionics kindly
supply to the visitor of this website an elucidative video
film made in his private laboratory shown in a straightforward
way the several stages of the manufacturing of three electrodes
valve or triode.
The triode type E, made by Philips in 1917,
similar in aspect to the French counter part type TM whose
inner structure is described in the video film.
TUBE MANUFACTURING By Claude Paillard
As a kind of support
to the visitor, the video film about the homemade triode
valve consists of a sequence of stages comprising:
1- THE MANUFACTURING OF THE
INNER ELECTRODES: grid, plate and filament or cathode. 2- THE GLASS STEN USED AS THE SUPPORT OF THE VALVE INNER
ELEMENTS.
3 – ASSEMBLING OF THE METALLIC CONTACTS IN THE GLASS
STEN
4- THE GLASS BULB
4.1 – THE EXHAUSTING TUBE
5 – ELECTRODES FIXING
5.1 – THE FILAMENT
5.2 – THE PLATE AND GRID
6 – THE CHEMICAL CLEANING PROCESS OF THE VALVE INNER
ELEMETS BEFOR THE AIR EXAUSTING.
7 – THE FINAL BULB ASSEMBLING
8 – THE BEGINNING OF THE VALVE BURNING – GETTER
9 – THE ASSEMBLING OF THE BULB IN THE SOCKET
10 – FIRST TESTINGS TO CHECK THE VALVE ELECTRICAL
BEHAVIOURING
11 - SEVERAL TYPES OF APPLICATION FOR THE HANDMADE TRIODE
11.1 – A SINGLE VALVE RADIO RECEIVER
11.2 – A TRANSMISTTER
12 – CLAUDE PAILLARD IN HIS PRIVATE LABORATORY SHOWING:
12.1 – THE EXHAUSTING OR VACUUM PRODUCTION IN THE
VALVE MANUFACTURING
THE VACUUM PROCESS IN THE VALVE MANUFACTURING THE GAEDE MERCURY PUMP
In studying the evolution of thermionic valve, the complex interrelationships
in the electricity-heat-vacuum field must be considered.
The studies on vacuum started with Otto von Guericke in
Germany followed by others researches as Robert Boyle, Denis
Papin, Swedenborg, Geissler, etc. Therefore, the invention
of the Gaede mercury pump is historically of great importance
as it was the first rapid-acting high vacuum since through
it physicist and engineers were able to make important discoveries
including certainly the improvement in valve manufacturing.
The Gaede mercury pump improved deeply the air exhausting
process in the valve glass bulbs. Basically this type of
pump consists of a drum of porcelain or iron, with complex
inner structure arranged to rotate in an enclosing cylinder.
The Gaede pump is illustrated as per the hereunder schematics:
On
the left the schematics of the Gaede pump where:
B - Mercury bearing
C - Mercury chamber
H - Hole
R - Bulb to be rarefied
S - Crankshaft
On the right, the manufacturing principle where the mercury
is turned in the chamber C, the contained air is pushed
along through the narrow spiral tail, being finally shoved
out at E where it is taken away by an auxiliary pump.
THE MECURY- JET DIFFUSION PUMP
Another type of pump
used by Irving Langmuir whose operation principle is
known as mercury-jet diffusion pump where:
A- Mercury reservoir
B- Tubing for the passage of the mercury vapor
C- Condensation tower
E – Outlet for the fore pump
R - Bulb to be rarefied
THE GEISSLER TUBE USED AS
A TYPE OF DISCHARGE VACUUM GAUGE
O tubo de descarga Geissler
é usado como um tipo de manômetro eletrônico
pois, através da passagem de uma corrente elétrica
permite mostrar os diversos níveis de rarefação.
O tubo Geissler
The exhausting stages shown
through the discharge shapes where:
A - Coil shaped discharged between the electrodes
B - Continuous discharge with an intensive hue
C - Dark spaces with faint hue
D - Larger dark spaces with fainter hue
E - Dark spaces inside the tube
F - Any hue inside the tube showing a greenish halo
only.
