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Voltage Pentode or Tetrode (under 100V) ·Pentode

12DZ6

Low-voltage remote-cutoff pentode for automobile and other 12 V RF/IF amplifier applications with direct battery-supply operation.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
7BK
Socket code
B7G
Base pins
7
Nominal heater
12.6 V / 190 mA

Description

12DZ6 — Remote-Cutoff Pentode

The 12DZ6 is a miniature, remote-cutoff pentode designed primarily for use as a radio-frequency (RF) amplifier in automobile radio receivers. It is specifically engineered to operate with its plate and screen grid voltages supplied directly from a 12-volt storage battery (typically a 6-cell storage-battery system), eliminating the need for a high-voltage B+ power supply. The tube features a 7-pin miniature construction and an indirectly heated, coated unipotential cathode.

Construction, Mechanical Specifications, and Pinout

The 12DZ6 is housed in a T-5 1/2 glass envelope with a small-button miniature 7-pin base (JEDEC No. E7-1). It can be operated in any mounting position.

Physical Dimensions

  • Maximum Overall Length: 2-1/8 inches
  • Maximum Seated Length: 1-7/8 inches
  • Length, Base Seat to Bulb Top (excluding tip): 1-1/2 inches ± 3/32 inch
  • Diameter: 0.650 to 0.750 inches

Pin Connections (Basing Designation 7BK)

Viewed from the bottom of the tube, the 7-pin base configuration provides the following connections:

  • Pin 1: Grid Number 1 (Control Grid)
  • Pin 2: Grid Number 3 (Suppressor Grid) and Internal Shield
  • Pin 3: Heater
  • Pin 4: Heater
  • Pin 5: Plate
  • Pin 6: Grid Number 2 (Screen Grid)
  • Pin 7: Cathode

Heater Characteristics and Automotive Operation

The 12DZ6 features a coated unipotential cathode. The heater is designed for operation on either AC or DC.

ParameterValue
Nominal Heater Voltage12.6 V
Nominal Heater Current0.190 A
Heater SupplyAC or DC

Automotive Voltage Variations

Because the tube is designed for direct operation from automotive electrical systems, its heater is rated to withstand the voltage fluctuations typical of a 12-volt storage battery (6-cell system) under charge and discharge conditions:

  • Absolute Voltage Range: Under no circumstances should the heater voltage fall below 10.0 volts or exceed 15.9 volts.
  • Recommended Range for Longest Life: 11 to 14 volts.
  • Operation Effects: Operating at or near the absolute limits of 10.0 V or 15.9 V results in a sacrifice in performance at the lower limit and a reduction in life expectancy at the upper limit. Equipment reliability is significantly enhanced by improved supply-voltage regulation.

Electrical Ratings

The maximum ratings for the 12DZ6 are established under the Design-Maximum System (or Design-Center System depending on the standard applied):

RatingValue
Maximum Plate Voltage16 V
Maximum Screen (Grid No. 2) Voltage16 V
Maximum Positive DC Grid No. 1 Voltage0 V
Maximum Heater-Cathode Voltage (Heater Positive)16 V
Maximum Heater-Cathode Voltage (Heater Negative)16 V
Maximum Grid No. 1 Circuit Resistance10 MΩ
Maximum Grid No. 3 Circuit Resistance10 MΩ

The suppressor grid (Grid No. 3) must be connected directly to the cathode at the socket.

Typical Operating Conditions and Characteristics

In typical Class A1 amplifier service, the 12DZ6 operates with low electrode potentials, matching the nominal 12.6 V battery supply:

  • Heater Voltage: 12.6 V
  • Plate Voltage: 12.6 V
  • Grid No. 3 (Suppressor) Supply Voltage: 0 V (connected to cathode)
  • Grid No. 2 (Screen) Voltage: 12.6 V
  • Grid No. 1 (Control Grid) Supply Voltage: 0 V
  • Grid No. 1 Resistor (Bypassed): 10 MΩ
  • Grid No. 3 Resistor (Bypassed): 10 MΩ
  • Plate Resistance (Approximate): 25,000 Ω
  • Transconductance: 3,800 µmhos
  • Plate Current: 4.5 mA
  • Screen Current (Grid No. 2 Current): 2.2 mA

Remote-Cutoff Action

To achieve remote-cutoff characteristics for automatic volume control (AVC) or automatic gain control (AGC) applications, a negative bias can be applied to the control grid. With an approximate bias of -10 V applied to Grid No. 1 (and Grid No. 3 in some configurations), the transconductance is reduced to approximately 10 µmhos.

Interelectrode Capacitances

The direct interelectrode capacitances of the 12DZ6 are measured without an external shield.

  • Grid No. 1 to Plate (Maximum): 0.05 pF to 0.15 pF
  • Input (Grid No. 1 to Cathode, Grid No. 3 & Internal Shield, Grid No. 2, and Heater): 9.5 pF
  • Output (Plate to Cathode, Grid No. 3 & Internal Shield, Grid No. 2, and Heater): 4.0 pF

These low capacitances, particularly the very low grid-to-plate feedback capacitance, make the tube highly stable in high-frequency RF amplifier stages.

Average Characteristics and Curves

The average characteristics of the 12DZ6 illustrate its performance under low-voltage conditions.

  • Plate Current vs. Plate Voltage: At a screen voltage of 12.6 V and Grid No. 3 connected to the cathode, the plate current curves show a typical pentode knee. For a control grid voltage of 0 V, the plate current rises rapidly and levels off above a few volts of plate potential, reaching approximately 4.5 mA at 12.6 V plate voltage.
  • Transconductance and Currents vs. Grid No. 1 Voltage: At a constant plate and screen voltage of 12.6 V, as the Grid No. 1 voltage is varied from 0 V down to -8 V or -10 V, the transconductance smoothly decreases from 3,800 µmhos toward zero, demonstrating the remote-cutoff characteristic. The plate current and screen current follow a similar downward trend, with screen current dropping from 2.2 mA at 0 V bias.

Technical Summary

The 12DZ6 is a 7-pin miniature remote-cutoff pentode designed for low-voltage operation directly from a 12-volt automotive storage battery. With a heater rating of 12.6 V at 0.190 A, it operates reliably under the voltage fluctuations of automotive electrical systems (10.0 V to 15.9 V). At its typical Class A1 operating point of 12.6 V on the plate and screen, it provides a transconductance of 3,800 µmhos, a plate resistance of approximately 25,000 ohms, and a plate current of 4.5 mA. Its remote-cutoff characteristic allows for effective gain control, making it highly suitable for RF amplifier stages in automotive receivers without requiring a high-voltage power supply.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
7BK
Socket code
B7G
Base pins
7
Nominal heater voltage
12.6 V
Nominal heater current
190 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

7BK - Terminal pinout

Electrical assignments shared by every tube using this base designation.

TerminalSectionConnectionEvidence
PIN1G1AG1 — Control Grid

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN2G3AG3 — Suppressor GridGroup 7BK2

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN2ISAIS — Internal ScreenGroup 7BK2

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN3H—H — Heater

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN4H—H — Heater

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN5PAP — Plate (Anode)

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN6G2AG2 — Screen Grid

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

PIN7KAK — Cathode

EIA chart transcription; independent manufacturer confirmation pending

Unverified

EIA Base Connections, printed page 128, 7BK

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
25000 Ω
Transconductance
0.0038 S
Max plate voltage
16 V
Max screen voltage
16 V

Promoted values are limited to values explicitly present in this supplied 12-V datasheet block; additional published values are retained in parameter rows.

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

  • Heater voltage

    12.6 V

    Nominal

  • Heater current

    150 mA

    Nominal

  • Plate voltage

    16 V

    Typical operating conditions

  • Screen voltage

    16 V

    Typical operating conditions

  • Plate current

    4.5 mA

    Typical operating conditions

Data set 02

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • GRID #

    1 mA

    GRID #1 TO PLATE (MAX.) 0.05 •— µuf

  • HEATER VOLTAGE

    12.6 V

    HEATER VOLTAGE 12.6A VOLTS

  • HEATER NEGATIVE WITH RESPECT TO CATHODE

    16 V

    HEATER NEGATIVE WITH RESPECT TO CATHODE 16 VOLTS

  • HEATER VOLTAGE BE LESS THAN

    10 V

    HEATER VOLTAGE BE LESS THAN 10.0 VOLTS OR MORE THAN 15.9 VOLTS. THESE EXTREME VARIATIONS IX

  • PLATE VOLTAGE

    12.6 V

    PLATE VOLTAGE 12,6 VOLTS

  • SCREEN VOLTAGE

    12.6 V

    SCREEN VOLTAGE 12.6 VOLTS

  • GRID #

    1 V

    GRID #1 SUPPLY VOLTAGE O VOLTS

  • PLATE RESISTANCE (APPROX.)

    2 Ω

    PLATE RESISTANCE (APPROX.) 2F OOO OHMS

  • PLATE CURRENT

    4.5 mA

    PLATE CURRENT 4,5 MA.

  • SCREEN CURRENT

    2.2 mA

    SCREEN CURRENT 2.2 MA.

  • GRIDS#

    1 V

    GRIDS#1 h #3 SUPPLY VOLTAGE (APPROX.)(GRID #1 TO PLATE)

  • GRID #

    3 MΩ

    GRID #3 RESISTOR (BYPASSED)` 1O MEGOHMS

Other

  • MAXIMUM PLATE VOLTAGE ]

    6 V

    MAXIMUM PLATE VOLTAGE ]6 voL rs

  • MAXIMUM SCREEN VOLTAGE

    16 V

    MAXIMUM SCREEN VOLTAGE 16 voLrs

  • MAXIMUM POSITIVE DC GRID #

    1 V

    MAXIMUM POSITIVE DC GRID #1 VOLTAGE O VOLTS

  • MAXIMUM GRID #

    1 mA

    MAXIMUM GRID #1 CIRCUIT RESISTANCE 10 ME60HMS

  • MAXIMUM GRID #

    3 mA

    MAXIMUM GRID #3 CIRCUIT RESISTANCE * lO MEGOHMS

Data set 03

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate Current

    4.5 mA

    ClassA

  • Screen Current

    2.2 mA

    ClassA

Data set 04

1971 RCA HB3 Binder 5 of 7

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

  • Voltage range (DC) — published value 1

    10 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Voltage range (DC) — published value 2

    15.9 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Current (Approx.) at 12.6 volts — published value 1

    12.6 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Current (Approx.) at 12.6 volts — published value 2

    0.19 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • internal shield, grid No.2, and heater. 9.5

    9.5

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • shield, grid No.2, and heater

    4

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Heater Voltage

    12.6 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Plate Voltage

    12.6 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Grid-No.2 Voltage

    12.6 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Grid-No.l Supply Voltage

    0 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Grid-No.l

    10 Mohm

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Grid-No.3 Resistor (Bypassed)

    10 Mohm

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Plate Resistance (Approx )

    25000 ohm

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Transconductance

    3800

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Plate Current

    4.5 mA

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Grid-No.2 Current

    2.2 mA

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • No.l to plate (Fanhos) = SO

    -10 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Pin 1 -Grid No.l — published value 1

    1

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Pin 1 -Grid No.l — published value 2

    4

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Pin 2 -Grid No.3, — published value 1

    2

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Pin 2 -Grid No.3, — published value 2

    5

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Internal

    6

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Shield

    7

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Pin 3 -Heater

    3

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Positive-bias value

    0 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • GRID—Ns2 VOLTS=12.6

    12.6 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • PLATE VOLTS=12.6

    12.6 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Heater voltage

    12.6 V

    Nominal heater rating

  • Heater current

    190 mA

    Nominal heater rating

Other

  • Grid No.l to plate — published value 1

    0 mA

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Grid No.l to plate — published value 2

    5 mA

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • PLATE VOLTAGE

    16 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • GRID-No.2 (SCREEN-GRID) VOLTAGE

    16 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Heater negative with respect to cathode. 16 max

    16 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Heater positive with respect to cathode. 16 max

    16 V

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Crid-No.l-Circuit Resistance

    10 mA

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.

  • Crid-No.3-Circuit Resistance

    10 mA

    Published value from the filename-designated RCA datasheet block; multiple numbers on one row represent separate limits or heater arrangements.