Power Amplifier Pentode
The 33 Vacuum tube is a power amplifier pentode for use
in the output stage of battery-operated receivers. The
low filament current required by the 33 makes this
tube particularly applicable for use in combination with
the 30 tube, 32 tube and/or 34 tube in radio sets where
economy of battery consumption is important.
The 33 is capable of producing greater power output than
three-electrode power amplifiers of the same plate
current drain. Furthermore, this tube has the design
feature of greater amplification than possible in a
three-electrode amplifier without serious sacrifice in
power output.
The power-handling ability of the 33 tube is made
possible by the addition of both a suppressor and a
screen between the grid and plate. The suppressor is
placed next to the plate and is connected inside the
tube to the filament. This design practically eliminates
the secondary emission effects which limit the power
output from four-electrode screen tubes. This tube was
first manufactured by RCA in 1932.
Electrical Data:
Filament Voltage ........................... 2.0 DC V
Filament Current ............................. 0.26 A
Preferred substitutes ..........................VT - 33