<< 300B 300B/n 300B/c 300B/SE 300B/2.5V/n 300B/2.5V/c Vacuum Tube






Classification- Dome-type or Aubergine-type bulb of glass, a white ceramic base with four-prong bayonet golden pins, oxide coated filamentary, solid plate or mesh or carbon plate triode.

Application -Audio frequency amplifier where power outputs of approximately 8.5watts or less is required at relatively low plate voltages.

Dimensions -Dimensions, outline diagrams of the tube and bases, and the arrangement of electrode connections to the base terminals are shown in Figures 1, 2 and 3.

Nominal operating conditions and parameters
Filament voltage* ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 5V or 2.5V
Nominal filament current ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 1.2A or 2.4A
Plate voltage ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 300V
Grid voltage** ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ -58V
Plate current ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 60mA
Amplification factor ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 3.85
Grid to plate transconductance ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 5.7mA / V
Grid current ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 0.05 ¦Ģ A
Plate resistance ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 700 ohms

*Alternating-current filament supply or Direct-current filament supply.
**Alternating-current filament supply is used. The grid and plate returns should be connected to a center tap on the secondary of the filament transformer.
Direct-current filament supply is used. The grid and platter returns are connected to the negative end of the filament.

Characteristics-Average characteristics
Figure 4. shown typical curves of plate currents of grid voltage for several values of plate voltages. It is alternating-current filament supply.

Fig 4

Limiting Operation Conditions for Safe Nor simultaneous ratings
Maximum plate voltage ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 450 volts
Maximum plate dissipation ”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­”­ 40 watts
Maximum plate current of average tube for fixed gird bias ”­”­”­”­ 70mA
Maximum plate current of manually adjusted gird or self-biasing circuit”­”­”­”­”­”­”­”­”­”­”­”­ 100mA