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Voltage Pentode - Sharp Cutoff (single) ·Pentode

12BV7

Sharp-cutoff pentode designed as a television video amplifier. Part of the 12BY7A/12BV7/12DQ7 replacement family, it is fundamentally a high-transconductance wideband signal tube rather than an audio power-output pentode.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
9BF
Socket code
B9A
Base pins
9
Nominal heater
12.6 V / 300 mA

Description

12BV7 — High-Transconductance Miniature Pentode

The 12BV7 is a miniature, high-transconductance sharp-cutoff power pentode designed primarily for service as a video output amplifier in television receivers. It is characterized by high power sensitivity and low interelectrode capacitances, enabling it to deliver relatively large output voltages across low values of plate load resistance with low plate-supply voltages. In application and electrical characteristics, the 12BV7 is closely related to the 12BY7 and 12BY7A.

Construction, Mechanical Specifications, and Pinout

The 12BV7 features a coated unipotential cathode housed in a T-6 1/2 glass envelope. It utilizes a small-button miniature 9-pin base (JEDEC E9-1) and can be mounted in any position.

Physical Dimensions

  • Maximum Overall Length: 2 5/8 inches
  • Maximum Seated Height: 2 3/8 inches (with some specifications indicating a nominal seated height of 2 inches ± 3/32 inches)
  • Maximum Diameter: 7/8 inches

Pin Connections (Basing Diagram 9BF)

The tube utilizes the EIA 9BF basing arrangement, which provides the following pin connections when viewed from the bottom of the tube:

Pin NumberConnection
Pin 1Cathode
Pin 2Grid Number 1 (Control Grid)
Pin 3Internal Shield and Grid Number 3 (Suppressor Grid)
Pin 4Heater
Pin 5Heater
Pin 6Heater Center-tap
Pin 7Plate
Pin 8Grid Number 2 (Screen Grid)
Pin 9Internal Shield and Grid Number 3 (Suppressor Grid)

Heater Characteristics

The 12BV7 heater is designed for either series or parallel operation, allowing flexibility in AC or DC series-string or parallel-connected entertainment receiver designs. It also features a controlled average warm-up time.

ParameterSeries ConnectionParallel Connection
Heater Voltage (AC or DC)12.6 V6.3 V
Heater Current0.3 A0.6 A
Average Warm-up Time—11 seconds

Maximum Ratings

The maximum ratings for the 12BV7 are defined under both the Design-Maximum and Design-Center rating systems. These limits must be observed to ensure reliable operation in video amplifier service.

Design-Maximum and Design-Center Limits

ParameterDesign-Maximum ValuesDesign-Center Values
Plate Supply Voltage330 V—
Plate Voltage—300 V
Screen-Grid (Grid No. 2) Voltage190 V175 V
Grid No. 3 (Suppressor Grid) Positive Voltage0 V—
Negative DC Grid No. 1 (Control Grid) Voltage55 V50 V
Positive DC Grid No. 1 (Control Grid) Voltage0 V—
Plate Dissipation6.5 W6.25 W
Screen-Grid (Grid No. 2) Dissipation / Input1.2 W1.0 W

Heater-Cathode Voltage Ratings

  • Design-Maximum System:
    • Peak value: ±200 V max
    • Average value: 100 V max
  • Design-Center System:
    • Heater negative with respect to cathode (Total DC + Peak): 200 V max
    • Heater positive with respect to cathode (DC component): 100 V max
    • Heater positive with respect to cathode (Total DC + Peak): 200 V max

Maximum Circuit Values

  • Grid-Number 1 Circuit Resistance (Fixed Bias): 0.25 Megohms max
  • Grid-Number 1 Circuit Resistance (Cathode Bias): 1.0 Megohm max

Electrical Characteristics and Typical Operation

The 12BV7 operates as a Class A1 amplifier. Depending on the circuit configuration and bias method, the tube exhibits the following typical characteristics:

ParameterOperating Point A (Cathode Bias)Operating Point B (Cathode Bias)Operating Point C (Fixed Bias / Cutoff Test)
Plate Voltage250 V250 V250 V
Screen Voltage150 V180 V180 V
Grid-Number 1 Voltage——-8 V
Cathode-Bias Resistor68 Ohms100 Ohms—
Plate Resistance (Approx.)85,000 Ohms93,000 Ohms—
Transconductance13,000 µmhos11,000 µmhos—
Plate Current27 mA26 mA0.5 mA (Minimum)
Screen Current6.0 mA5.75 mA—
Grid-No. 1 Cutoff Voltage (approx. for plate current of 20 µA)-12 V-11.5 V—
Triode Amplification Factor (Triode Connected)28——

Direct Interelectrode Capacitances

The interelectrode capacitances of the 12BV7 vary slightly depending on whether an external shield is used during measurement.

Capacitance ParameterWithout External ShieldWith External Shield
Grid No. 1 to Plate0.055 pF0.063 pF
Input (Grid No. 1 to Cathode, Heater, Grid No. 2, Grid No. 3, and Internal Shield)11.0 pF10.2 pF
Output (Plate to Cathode, Heater, Grid No. 2, Grid No. 3, and Internal Shield)3.0 pF3.5 pF

Characteristic Curves and Interpretation

The electrical behavior of the 12BV7 is further illustrated by its average characteristic curves:

  • Average Plate Characteristics: These curves plot plate current against plate voltage for various grid-No. 1 voltages ranging from positive values (such as +2.0 V and +1.0 V) down to negative values (such as -7.0 V), with the screen voltage held constant at 150 V. The curves demonstrate a sharp knee at low plate voltages, indicating efficient operation and the ability to deliver high output voltage swings into low load resistances.
  • Average Screen Characteristics: These curves display screen current as a function of plate voltage for different grid-No. 1 voltages, with the screen voltage maintained at 150 V. Screen current rises significantly at very low plate voltages where plate current falls.
  • Average Transfer Characteristics: These curves plot plate current and screen current against grid-No. 1 voltage for various screen voltages (ranging from 25 V to 150 V) at a constant plate voltage of 250 V. They show the control grid's modulation capability and the cutoff behavior of the tube.
  • Transconductance Characteristics: Curves of transconductance versus grid-No. 1 voltage show that the transconductance rises rapidly as the grid bias becomes less negative, peaking near 20,000 micromhos under high screen voltage conditions.

Related Designations and Replacements

The 12BV7 is closely related to the 12BY7 and 12BY7A pentodes. In many television receiver applications, the 12BY7A, 12BV7, and 12DQ7 are grouped together as interchangeable or direct replacements for one another, sharing similar physical dimensions, pinouts, and general electrical characteristics.

Technical Summary

The 12BV7 is a high-transconductance, sharp-cutoff miniature power pentode featuring a 9-pin small-button base (EIA 9BF) and a T-6 1/2 glass envelope. Designed primarily for television video output amplifier service, it operates with a flexible series (12.6 V / 0.3 A) or parallel (6.3 V / 0.6 A) heater arrangement. Under typical Class A1 operating conditions, it exhibits a transconductance of 11,000 to 13,000 µmhos, a plate resistance of 85,000 to 93,000 ohms, and a plate current of 26 to 27 mA. With a plate dissipation rating of up to 6.5 watts (Design-Maximum) and low interelectrode capacitances, the 12BV7 is optimized for delivering large output voltages across low-value load resistances.

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
9BF
Socket code
B9A
Base pins
9
Nominal heater voltage
12.6 V
Nominal heater current
300 mA
Parallel heater voltage
6.3 V
Parallel heater current
600 mA
Series capable
Yes

9BF - Terminal pinout

Electrical assignments shared by every tube using this base designation.

TerminalSectionConnectionEvidence
PIN1KAK — Cathode

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN2G1AG1 — Control Grid

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN3G3AG3 — Suppressor Grid

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN4H—H — Heater

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN5H—H — Heater

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN6HCT—HCT — Heater Center Tap

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN7PAP — Plate (Anode)

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN8G2AG2 — Screen Grid

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

PIN9G3AG3 — Suppressor Grid

EIA chart transcription; manufacturer corroboration pending

Unverified

EIA Base Connections, printed page 131, 9BF

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
85000 Ω
Transconductance
0.013 S
Max plate voltage
300 V
Max screen voltage
175 V
Max plate dissipation
6.25 W
Max screen dissipation
1 W

Published Westinghouse ratings, characteristics, capacitances, pulse/deflection data, and typical operating conditions promoted where applicable; additional values retained as parameters.

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

1965 Westinghouse Data Book

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

  • Series heater voltage

    12.6 V

    SeriesHeater

  • Series heater current

    300 mA

    SeriesHeater

  • Parallel heater voltage

    6.3 V

    ParallelHeater

  • Parallel heater current

    600 mA

    ParallelHeater

  • Transconductance

    13000 uS

  • Plate resistance

    68000 ohm

Other

  • Typical plate voltage

    250 V

  • Heater-cathode voltage maximum

    200 V

Application

  • Application

    Video amplifier

Capacitance

  • Grid-to-plate capacitance

    0.055 pF

  • Output capacitance

    3 pF

Data set 02

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate Current

    27 mA

    ClassA

  • Screen Current

    6 mA

    ClassA

Data set 03

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Heater Voltage (ac/dc) 12.6

    6.3 V

    Published in approved 12BV7 target entry; Section1

  • Heater Current 0.3

    600 mA

    Published in approved 12BV7 target entry; Section1

  • Heater Warm-up Time (Average)

    11 seconds

    Published in approved 12BV7 target entry; Section1

  • Plate Supply Voltage

    330 V

    Published in approved 12BV7 target entry; Section1

  • Grid-No.3 (Suppressor-Grid) Voltage, Positive value

    0 V

    Published in approved 12BV7 target entry; Section1

  • Grid-No.2 (Screen-Grid) Voltage

    190 V

    Published in approved 12BV7 target entry; Section1

  • Negative-bias value

    65 V

    Published in approved 12BV7 target entry; Section1

  • Positive-bias value

    0 V

    Published in approved 12BV7 target entry; Section1

  • Plate Dissipation

    6.5 W

    Published in approved 12BV7 target entry; Section1

  • Grid-No.2 Input

    1.2 W

    Published in approved 12BV7 target entry; Section1

  • grid-no

    2 V

    Published in approved 12BV7 target entry; Section1

  • For fixed-bias operation

    0.25 MΩ

    Published in approved 12BV7 target entry; Section1

  • For cathode-bias operation

    1 MΩ

    Published in approved 12BV7 target entry; Section1

  • Heater Voltage (ac/dc) 6.3 16.8

    25.3 V

    Published in approved 12BV7 target entry; Section1

  • Heater Current 0.6 0.45

    300 mA

    Published in approved 12BV7 target entry; Section1

  • Heater Warm-up Time {Average) 11 11

    11 seconds

    Published in approved 12BV7 target entry; Section1

  • Peak Inverse Plate Voltage*

    5000 V

    Published in approved 12BV7 target entry; Section1

  • Peak Plate Current

    1200 mA

    Published in approved 12BV7 target entry; Section1

  • Average Plate Current

    250 mA

    Published in approved 12BV7 target entry; Section1

  • Plate Dissipation

    4.75 W

    Published in approved 12BV7 target entry; Section1

  • Peak value +800

    -5000 V

    Published in approved 12BV7 target entry; Section1

  • Average value -(-100

    -900 V

    Published in approved 12BV7 target entry; Section1

Capacitance

  • Grid No.l to Plate

    0.063 pF

    Published in approved 12BV7 target entry; Section1

  • and Internal Shield

    10.2 pF

    Published in approved 12BV7 target entry; Section1

  • Plate to Cathode, Heater, Grid No.2, and Internal Shield

    3.5 pF

    Published in approved 12BV7 target entry; Section1

  • Plate to Cathode and Heater

    12 pF

    Published in approved 12BV7 target entry; Section1

  • Cathode to Plate and Heater

    9.5 pF

    Published in approved 12BV7 target entry; Section1

  • Heater to Cathode

    2.8 pF

    Published in approved 12BV7 target entry; Section1

Characteristic

  • Plate Supply Voltage

    250 V

    Published in approved 12BV7 target entry; Section1

  • Grid-No.2 Supply Voltage

    180 V

    Published in approved 12BV7 target entry; Section1

  • Cathode-Bias Resistor

    100 Ω

    Published in approved 12BV7 target entry; Section1

  • Plate Resistance (Approx.)

    93000 Ω

    Published in approved 12BV7 target entry; Section1

  • Plate Current

    26 mA

    Published in approved 12BV7 target entry; Section1

  • Grid-No.2 Current B

    75 mA

    Published in approved 12BV7 target entry; Section1

  • Grid-No.l Voltage (Approx.) for plate current of 20 jtA

    11.6 V

    Published in approved 12BV7 target entry; Section1