Gas Triode ~ Detector
The Sylvania SX-200-A / SX200A Vacuum tube is a gas triode
detector. It was first manufactured in April 1926.
In 1925 RCA replaced the UV200 with the UX200.
In May 1926 RCA announced the UX200A as a new detector
tube, replacing the UX200. The UV200 and UX200 tubes
used Argon gas.The UX200A contains caesium
vapor instead of argon gas. This produced
a much more stable operation and increase of sensitivity.
The UX200 has a thoriated filament but at that time,
1926, was already outdated and only being used as
replacement for the UX200A.
Electrical Data:
Heater Voltage ........................ 5 V
Heater Current ..................... 0.25 A
Preferred Substitutes ............... UX200A, D400A, 00A,
TC200A, 200A