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Voltage Dual Pentode ·Pentode-Pentode

3BU8

Sharp-cutoff twin pentode designed as combined television sync separator, sync clipper, and automatic-gain-control amplifier.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
-
Socket code
B9A
Base pins
9
Nominal heater
3.15 V / 600 mA

Description

Sharp-cutoff twin pentode used as combined sync separator, sync clipper, and AGC amplifier in television receivers.

Socket description

Small-button Noval 9-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B9A
Base pins
9
Nominal heater voltage
3.15 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

2 physical sections, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Transconductance
0.001 S
Max plate voltage
300 V
Max screen voltage
150 V
Max plate dissipation
1.1 W
Max screen dissipation
0.75 W
Max cathode current
12 mA
Rectifier warm-up time
11 s

Published ratings/characteristics promoted where semantically applicable; supplemental values retained in parameter table.

Section 2

Pentode

X-ray radiationInterelectrode capacitances
Transconductance
0.001 S
Max plate voltage
300 V
Max screen voltage
150 V
Max plate dissipation
1.1 W
Max screen dissipation
0.75 W
Max cathode current
12 mA

Published ratings, characteristics, operating points and capacitances reviewed.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate Voltage

    100 V

    EachSection

  • Screen Voltage

    67.5 V

    BothSections

Characteristic

  • Grid4Transconductance

    1000 uS

    EachSectionSeparately

Data set 02

1965 Westinghouse Data Book

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • Heater Voltage

    3.15 V

  • Heater Current

    600 mA

  • ControlledWarmupHeater

    1 boolean

  • Heater Warmup Time

    11 s

  • Grid3 To Plate Capacitance

    1.9 pF

    EachUnit

  • Grid1 To All Capacitance

    6 pF

  • Grid3ToAllCapacitance

    3.6 pF

    EachUnit

  • Plate To All Capacitance

    3 pF

    EachUnit

  • Grid3Unit1ToGrid3Unit2CapacitanceMaximum

    0.015 pF

  • Grid3 Transconductance

    180 uS

    EachUnit

  • Grid1Transconductance

    1500 uS

    EachUnit

  • Grid3CutoffVoltage

    -7.5 V

    EachUnit

  • Grid1CutoffVoltage

    -2.3 V

    EachUnit

  • Application

    Television sync separator and keyed AGC rectifier

Other

  • Plate Voltage Maximum

    300 V

    EachUnit

  • Grid1CircuitResistanceMaximum

    0.5 Mohm

  • Grid3CircuitResistanceMaximum

    0.5 Mohm

    EachUnit

  • Plate Voltage

    100 V

    EachUnit

  • Grid3 Voltage

    0 V

    EachUnit

  • Grid2 Voltage

    67.5 V

    EachUnit

  • Plate Current

    2.2 mA

    EachUnit

Data set 03

1966 Tung Sol Electronic Tubes 1 of 4

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • Heater voltage

    3.15 V

    Published heater rating

  • Heater current

    600 mA

    Published heater rating

  • Pentode transconductance

    9700 µS

    PentodeSection

  • Triode amplification factor

    65

    TriodeSection

Other

  • Pentode plate voltage

    200 V

    PentodeSection

  • Pentode screen voltage

    200 V

    PentodeSection

  • Pentode plate current

    18 mA

    PentodeSection

  • Triode plate voltage

    200 V

    TriodeSection

  • Triode plate current

    3 mA

    TriodeSection

Data set 04

1971 RCA HB3 Binder 4 of 7

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Heater Current

    560 mA to 640 mA

    Published nominal ± tolerance

  • Heater Voltage

    3.15 V

    At heater current 0.6 A

  • Warm-Up Time

    11 s

    Average

  • Plate Voltage

    300 V

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Screen Voltage

    150 V

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Cathode Current

    12 mA

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Plate Dissipation

    1.1 W

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Screen Input

    0.75 W

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Plate Voltage

    100 V

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Screen Voltage

    67.5 V

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Plate Current

    2.2 mA

    Inherited from explicitly referenced 6-volt parent type; heater variant

Characteristics

  • Grid No.1 Transconductance

    1500 µS

    Inherited from explicitly referenced 6-volt parent type; heater variant

  • Grid No.3 Transconductance

    180 µS

    Inherited from explicitly referenced 6-volt parent type; heater variant

Data set 05

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Maximum plate voltage

    300 V

    Published maximum rating

  • Maximum screen-grid voltage

    150 V

    Published maximum rating

  • Maximum plate dissipation

    1.1 W

    Published maximum rating

SECTION 2

Pentode

Other

  • Tube Voltage Drop for plate current of

    140 mA

    Tube Voltage Drop for plate current of 140 mA 12 volts

  • Heater Voltage (ac/dc) 3.15 4.2

    6.3 V

    Heater Voltage (ac/dc) 3.15 4.2 6.3 volts

  • Heater Current 0.6 0.45

    300 mA

    Heater Current 0.6 0.45 0.3 ampere

  • Heater Warm-up Time (Average) 11

    11 s

    Heater Warm-up Time (Average) 11 11 seconds

  • Plate Voltage (Each Unit)

    300 V

    Plate Voltage (Each Unit) 300 volts

  • Grid-No.2 (Screen-Grid) Voltage

    150 V

    Grid-No.2 (Screen-Grid) Voltage 150 volts

  • Grid-No.l (Control-Grid) Voltage, Negative bias value

    50 V

    Grid-No.l (Control-Grid) Voltage, Negative bias value . . . 50 volts

  • Cathode Current

    12 mA

    Cathode Current 12 mA

  • Plate Dissipation (Each Unit)

    1.1 W

    Plate Dissipation (Each Unit) 1.1 watts

  • DC Plate Voltage

    300 V

    DC Plate Voltage 300 volts

  • Grid-No.2 (Screen-Grid) Supply Voltage

    300 V

    Grid-No.2 (Screen-Grid) Supply Voltage 300 volts

  • Maximum plate voltage

    300 V

    Published maximum rating

  • Maximum screen-grid voltage

    150 V

    Published maximum rating

  • Maximum plate dissipation

    1.1 W

    Published maximum rating

Characteristic

  • Plate Voltage (Each Unit) 100

    100 V

    Plate Voltage (Each Unit) 100 100 volts

  • Grid-No-3 Voltage (Each Unit) —10

    0 V

    Grid-No-3 Voltage (Each Unit) —10 0 volts

  • Grid-No.2 Voltage 67.6

    67.5 V

    Grid-No.2 Voltage 67.6 67.5 volts

  • Plate Current (Each Unit)

    2.2 mA

    Plate Current (Each Unit) 2.2 mA

  • Grid-No.2 Current 6.5

    3.3 mA

    Grid-No.2 Current 6.5 3.3 mA

  • Cathode Current 6.6

    7.8 mA

    Cathode Current 6.6 7.8 mA

  • Plate Voltage 100

    100 V

    Plate Voltage 100 100 volts

  • Grid-No.3 Voltage 0

    0 V

    Grid-No.3 Voltage 0 0 volts

  • Grid-No.2 Voltage 67.5

    67.5 V

    Grid-No.2 Voltage 67.5 67.5 volts

  • Plate Current —

    2.2 mA

    Plate Current — 2.2 mA

  • Grid-No.3-Circuit Resistance (Each Unit)

    0.5 Mohm

    Grid-No.3-Circuit Resistance (Each Unit) 0.5 megohm

  • Grid-No.l-Circuit Resistance

    0.5 Mohm

    Grid-No.l-Circuit Resistance 0.5 megohm

  • Heater Voltage (ac/dc) 6.3

    12.6 V

    Heater Voltage (ac/dc) 6.3 12.6 volts

  • Heater Current 0.9

    450 mA

    Heater Current 0.9 0.45 ampere

  • Heater Warm-up Time

    11 s

    Heater Warm-up Time 11 seconds