Western electric 300 b schematic
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Page 1
Wesrem Electric Company
No.300-A & 300-B VACUUM TUBES
Classification-Moderate power, filamentary triodes for Class A service
These tubes are identical except for the location of the bayonet pin in the base.
ApplicatiOIl-Audimfrequency amplifier in positions where power outputs of approximately ten
watts or less are required at relatively low plate voltages.
Dimensions-Dimensions, outline diagrams of the tubes and bases, and the anangement of elec-
trode connections to the base terminals are shown in Figures 1 and 2.
Copyright 1939, Western Electric Company, Incorporated
7303,
Page 2
Western Electric Company
No.300-A & 300-B VACUUM TUBES
Base and Mounting-These vacuum tubes employ medium, four-pin thrust type bases suitable
for use in Western Electric 14313 or similar sockets. The BOOB 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 hori»
zontal position, the plane of the filament, which is indicated in Figure 2, should be vertical.
Average Direct Interelectrode Capacitances
Grid to plate ............ ,, .............. .,.. . ............. .. 15 uuf,
Grid to filament. . . , 9 pal
Plate to filament . ............................... . . 4.3mm
Filament Rating
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. hen 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.
Characteristics-Average Characteristicsi(F.;= 5.0 volts, a.c., Eb=300 volts and EC: -61 volts).
Plate current ............................. . . ............... 60 milliamperes
Amplification factor, . ,. . . . . .................. . . . ........ 3.85
Plate resistance ............................................. 700 ohms
Grid to plate transconductance ................................. 5500 micromhos
Plate»Current characteristics for a typical tube are shown in Figure 3 as functions of grid bias,
for alternating-Current filament supply. The corresponding amplificationifactor, plate-resistance,
and transconductance characteristics are given in Figures 4, 5 and 6, respectively. When direct-
current filament supply is used, and the grid and plate returns are connected to the negative ent
)f the filament, the same Characteristics are applicable if 3.5 is subtracted from the numerical valu
{each grid bias.
'304e