300B/n DOME/茄型 网屏

Classification-Dome-type or Aubergine-type bulb of glass, a white ceramic base with four-prong bayonet gold pins , oxide coated filamentary, solid plate, mesh plate, cabon 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...............................5 V or 2.5V
Nominal filament current................1.2A or 2.5A
Plate voltage.....................................300V
Grid voltage...................................－58 V
Plate current.....................................60 mA
Amplification factor.........................3.85
Grid to plate transconductance ...5.7mA/V
Grid current......................................0.05 μA
Plate resistance..............................700 ohm

*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-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