Moderate power, filamentary triodes for Class-A service.
Audio-frequency amplifier in positions where power outputs of approximately ten watts or less are required at relatively low plate voltages.
Dimensions, outline diagrams of the tubes and bases, and the arrangement of electrode connections to the base terminals are shown in Figures 1 and 2.
Base and Mounting
These vacuum tubes employ medium, four-pin thrust type bases suitable for use in Western Electric 143B or similar sockets. The 300B tube has the bayonet pin so located that it may also be mounted in a Western Electric 100M, 115B, or similar socket.
The tubes may be mounted in either a vertical or horizontal position. If mounted In a horizontal position, the plane of the filament, which is indicated In Figure 2, should be vertical.
Average Direct Interelectrode Capacitances
Grid to plate 15 µµf.
Grid to filament 9 µµf.
Plate to filament 4.3 µµf.
Filament voltage 5.0 volts, a.c. or d.c.
Nominal filament current 1.2 amperes
The filaments of these tubes are designed to operate on a voltage basis and should be operated at as near the rated voltage as possible. When alternating current is used for heating the filament, the grid and plate returns should be connected to a center tap on the secondary of the filament transformer.
MANUFACTURED IN THE U.S.A.
Electron tubes carry a Limited Warranty of ninety (90) days to the end user. The Limited Warranty period may be extended to five (5) years upon return of the warranty card WITHIN 10 DAYS that is included with your electron tube purchase.