<< 300B/c/+ Vacuum Tube



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

Application -Audio frequency amplifier where power outputs of approximately 22.5watts 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.

Nominal operating conditions and parameters
Filament voltage* 5V
Nominal filament current 2.4A
Plate voltage 400V
Grid voltage** -70V
Plate current 120mA
Amplification factor 3.85
Grid to plate transconductance 8.5mA / V
Grid current 0.05 A
Plate resistance 450 ohms
Load resistance 2.0 kohms

*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 3. shown typical curves of plate currents of grid voltage for several values of plate voltages. It is alternating-current filament supply.

Fig 3

Limiting Operation Conditions for Safe Nor simultaneous ratings
Maximum plate voltage 450 volts
Maximum plate dissipation 80 watts