300B Directly Heated Power Triode

General Information

The 300B is a directly heated power triode, with a 4 pin base. The 300B has good linearity, low noise and good reliability, and is intended for use in an audio power amplifier.

CHARACTERISTICS

Heater Voltage                                                       5.0 volts
Heater Current                                                      1.2 amperes
Anode Current      Eb = 350 volts                         60mA
Power Output        Ec = -74 volts                          8 Watts  

MAXIMUM RATINGS

Maximum anode voltage                                         Va            400                          V
Maximum anode dissipation                                   Wa          36                            W
Maximum Cathode Current                                    Ik             100                          mA
Maximum Grid circuit resistance (auto bias)        Rg            0.25                         MΩ
Maximum Grid circuit resistance(fixed bias)         Rg’           0.05                         MΩ

DIMENSIONS

Maximum overall length                                                         165.1                       mm
Maximum seated height                                                          134.8                       mm
Maximum diameter                                                                 61.7                         mm
Base                                                                                        UX4

BASE CONNECTIONS

Pin1         Heater
Pin2         Anode
Pin3         Grid
Pin4         Heater   

TYPICAL OPERATION

Class A single Valve Amplifier:

Heater Voltage                                                       5                              5              V
Anode Voltage                                                        300                          350          V
Grid Voltage                                                           -61                           -74           V
Maximum Anode Current                                      74                            77            mA
Transconductance                                                  5300                        5000        µ Ω
Amplification Factor                                               3.9                           3.9
Load resistance                                                      3.0                           4.0           KΩ
Anode resistance                                                   740                          790          Ω
Maximum Power Output                                       6                              7              watts
Harmonic distortion                                              5                              5              per cent

Class A Push Pull Amplifier:

Note values are for 2 valves:-

Heater Voltaage                                                     5                              5              V
Anode Voltage                                                        300                          350          V
Grid Voltage                                                           -61                           -67.5        V
Peak Grid to Grid Voltage                                     122                          135          V
Maximum Anode Current                                      100                          170          mA
Transconductance                                                  5300                        5000        µ Ω
Amplification Factor                                               3.9                           3.9
Load resistance Anode to Anode                          4.0                           4.0           KΩ
Maximum Power Output                                       10                            20            watts
Harmonic distortion                                              4.5                           2              per cent