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Voltage - Dual Triode (similar) ·Triode-Triode

12FQ7

Medium-mu twin triode for general voltage-amplifier, phase-inverter, and driver service, electrically suited to applications requiring moderate gain and useful current capability.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
9LP
Socket code
B9A
Base pins
9
Nominal heater
12.6 V / 300 mA

Description

12FQ7 — Medium-Mu Twin Triode Vacuum Tube

An indirectly heated, 9-pin miniature double triode designed for use as a combined vertical- and horizontal-deflection oscillator in television receivers and for general-purpose Class A1 amplification.

Overview

The 12FQ7 is a miniature, medium-mu twin triode featuring two independent triode sections in a single T-6 1/2 glass envelope. It is primarily designed for service in television receivers as a combined vertical- and horizontal-deflection oscillator in both color and black-and-white systems. Additionally, it is highly suitable for use as a resistance-coupled Class A1 amplifier.

The 12FQ7 is electrically identical to the 6FQ7/6CG7 and 8FQ7/8CG7 vacuum tubes, differing only in its heater voltage and current ratings. It features a controlled heater warm-up time of 11 seconds, making it suitable for series-string heater arrangements.

Heater and Physical Specifications

The 12FQ7 utilizes an indirectly heated, unipotential cathode design. The heater is designed to operate from either an AC or DC supply.

ParameterValue
Heater Voltage (AC/DC)12.6 V
Heater Current0.300 ± 0.020 A (0.3 A nominal)
Average Heater Warm-up Time11 seconds
Maximum Heater-Cathode Voltage (Heater Negative to Cathode)200 V (Total DC and Peak)
Maximum Heater-Cathode Voltage (Heater Positive to Cathode)100 V DC, 200 V (Total DC and Peak)

The physical dimensions of the tube are standardized under the miniature T-6 1/2 outline:

  • Base: Button 9-Pin, E9-1
  • Basing Designation: 9LP
  • Maximum Diameter: 0.875 inches
  • Maximum Seated Height: 2.375 inches
  • Maximum Overall Height: 2.625 inches
  • Mounting Position: Any

Pinout and Base Connections

The 12FQ7 uses a standard miniature 9-contact socket. The 9LP basing configuration provides independent connections for the electrodes of both triode units, with the exception of the shared heater.

  • Pin 1: Plate (Unit 2)
  • Pin 2: Grid (Unit 2)
  • Pin 3: Cathode (Unit 2)
  • Pin 4: Heater
  • Pin 5: Heater
  • Pin 6: Plate (Unit 1)
  • Pin 7: Grid (Unit 1)
  • Pin 8: Cathode (Unit 1)
  • Pin 9: Internal Connection (IC) / No Connection (NC)

Note on Pin 9: Pin 9 is designated as an internal connection or no connection depending on the manufacturer. To maintain circuit interchangeability across different brands, this pin must not be used for any external circuit connections.

Electrical Characteristics and Class A1 Operation

Each triode section of the 12FQ7 exhibits moderate amplification factor and relatively low plate resistance. Under typical Class A1 amplifier conditions, the operating parameters are defined at two distinct plate voltage points:

ParameterOperating Point AOperating Point B
Plate Voltage90 V250 V
Grid Voltage0 V-8 V
Amplification Factor2020
Plate Resistance (Approx.)6,700 Ω7,700 Ω
Transconductance3,000 µmhos2,600 µmhos
Plate Current10 mA9 mA
Grid Voltage for 10 µA Plate Current (Approx.)-7 V-18 V
Plate Current at -12.5 V Grid Bias—1.3 mA

Design-Maximum Ratings (Class A1 Amplifier)

  • Maximum DC Plate Voltage: 330 V
  • Maximum Positive-Bias Grid Voltage: 0 V
  • Maximum Cathode Current: 22 mA
  • Maximum Plate Dissipation (Either Plate): 4.0 W
  • Maximum Plate Dissipation (Both Plates Operating): 5.7 W
  • Maximum Grid Circuit Resistance (Fixed-Bias): 1.0 MΩ

Deflection Oscillator Service

When operated as a vertical- or horizontal-deflection oscillator in a 525-line, 30-frame television system, the 12FQ7 is subject to specific design-maximum ratings tailored to pulsed wave-shape conditions.

Rating ParameterVertical-Deflection OscillatorHorizontal-Deflection Oscillator
Maximum DC Plate Voltage330 V330 V
Maximum Peak Negative-Pulse Grid Voltage440 V660 V
Maximum Peak Cathode Current77 mA330 mA
Maximum Average Cathode Current22 mA22 mA
Maximum Plate Dissipation (Either Plate)4.0 W4.0 W
Maximum Plate Dissipation (Both Plates Operating)5.7 W5.7 W
Maximum Grid-Circuit Resistance (Self-Bias)2.2 MΩ2.2 MΩ

Interelectrode Capacitances

The direct interelectrode capacitances of the 12FQ7 are measured without an external shield. The values for each independent triode section are as follows:

Capacitance ParameterUnit No. 1Unit No. 2
Grid to Plate3.6 pF3.8 pF
Input: Grid to (Cathode + Heater)2.4 pF2.4 pF
Output: Plate to (Cathode + Heater)0.34 pF0.26 pF
Plate of Unit 1 to Plate of Unit 21.0 pF1.0 pF

Technical Summary

The 12FQ7 is a versatile, 9-pin miniature medium-mu twin triode. Operating with a 12.6 V, 0.3 A heater with a controlled 11-second warm-up time, it is optimized for series-string television designs. With an amplification factor of 20, transconductance up to 3,000 µmhos, and a plate dissipation limit of 4 watts per section (5.7 watts combined), it provides robust performance in both low-frequency Class A1 amplification and demanding television deflection oscillator circuits.

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
9LP
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

9LP - 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

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
6700 Ω
Transconductance
0.003 S
Amplification factor
20
Max plate voltage
330 V
Max cathode current
22 mA

Supplied sheet explicitly states this is the same as 6FQ7 except for heater characteristics. Parent electrical table was not present in the currently available local corpus, so no unsupported promoted values were invented.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
6700 Ω
Transconductance
0.003 S
Amplification factor
20
Max plate voltage
330 V
Max cathode current
22 mA

Physical triode row restored under current one-row-per-physical-section policy.

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

1971 RCA HB3 Binder 5 of 7

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Current — published value 1

    0.3

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

  • Current — published value 2

    0.02

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

  • Voltage (ac or dc) at 0.300 A — published value 1

    0.3 V

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

  • Voltage (ac or dc) at 0.300 A — published value 2

    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

    300 mA

    Nominal heater rating

Data set 02

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Heater Voltage (ac/dc) 6.3 8.4

    12.6 V

    Published in approved 12FQ7 target entry; Section1

  • Heater Current 0.6 0.45

    300 mA

    Published in approved 12FQ7 target entry; Section1

  • Heater Warm-up Time (Average)

    11 seconds

    Published in approved 12FQ7 target entry; Section1

  • Grid to Plate 3.6

    3.8 pF

    Published in approved 12FQ7 target entry; Section1

  • Grid to Cathode and Heater 2.4

    2.4 pF

    Published in approved 12FQ7 target entry; Section1

  • Plate to Cathode and Heater 0.34

    0.26 pF

    Published in approved 12FQ7 target entry; Section1

  • Plate Voltage

    330 V

    Published in approved 12FQ7 target entry; Section1

  • Grid Voltage, Positive-bias value

    0 V

    Published in approved 12FQ7 target entry; Section1

  • Cathode Current

    22 mA

    Published in approved 12FQ7 target entry; Section1

  • For both plates with both units opex'ating

    5.7 W

    Published in approved 12FQ7 target entry; Section1

  • Plate Voltage 90

    250 V

    Published in approved 12FQ7 target entry; Section1

  • Grid Voltage 0

    -8 V

    Published in approved 12FQ7 target entry; Section1

  • Plate Resistance (Approx.) 6700

    7700 Ω

    Published in approved 12FQ7 target entry; Section1

  • DC Plate Voltage 330

    330 V

    Published in approved 12FQ7 target entry; Section1

  • Peak Negative-Pulse Grid Voltage 440

    660 V

    Published in approved 12FQ7 target entry; Section1

  • Peak Cathode Current 77

    330 mA

    Published in approved 12FQ7 target entry; Section1

  • Average Cathode Current 22

    22 mA

    Published in approved 12FQ7 target entry; Section1

  • For either plate 4

    4 W

    Published in approved 12FQ7 target entry; Section1

  • For both plates with both units operating . . . 5.7

    6.7 W

    Published in approved 12FQ7 target entry; Section1

  • Grid-Circuit Resistance 2.2

    2.2 MΩ

    Published in approved 12FQ7 target entry; Section1

  • Heater Voltage (ac/dc) 2.4 2.9

    6.3 V

    Published in approved 12FQ7 target entry; Section1

  • Heater Current 0.6 0.45

    200 mA

    Published in approved 12FQ7 target entry; Section1

  • Heater Warm-up Time (Average) 11

    11 seconds

    Published in approved 12FQ7 target entry; Section1

  • Plate Voltage

    300 V

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.3 (Screen-Grid) Voltage

    150 V

    Published in approved 12FQ7 target entry; Section1

  • Negative-bias value

    60 V

    Published in approved 12FQ7 target entry; Section1

  • Positive-bias value

    0 V

    Published in approved 12FQ7 target entry; Section1

  • Cathode Current

    20 mA

    Published in approved 12FQ7 target entry; Section1

  • Plate Dissipation

    3.25 W

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.3 Input

    0.16 W

    Published in approved 12FQ7 target entry; Section1

  • Plate Voltage

    275 V

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.3 Voltage

    135 V

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.l Voltage

    -0.2 V

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.l-Circuit Resistance, for fixed-bias operation

    0.5 MΩ

    Published in approved 12FQ7 target entry; Section1

Capacitance

  • Plate of Unit No.l to Plate of Unit No

    2 pF

    Published in approved 12FQ7 target entry; Section1

  • Grid No.l to Plate 0.03

    0.016 pF

    Published in approved 12FQ7 target entry; Section1

  • No.3, and Grid No.4

    4.8 pF

    Published in approved 12FQ7 target entry; Section1

  • and Grid No

    4 pF

    Published in approved 12FQ7 target entry; Section1

Characteristic

  • Plate Current 10

    9 mA

    Published in approved 12FQ7 target entry; Section1

  • Grid Voltage (Approx.) for plate current of 10 /iA. —7

    -18 V

    Published in approved 12FQ7 target entry; Section1

  • 12.5 volts

    1.3 mA

    Published in approved 12FQ7 target entry; Section1

  • Plate Resistance (Approx. )

    0.24 MΩ

    Published in approved 12FQ7 target entry; Section1

  • Transconductance

    10000 µS

    Published in approved 12FQ7 target entry; Section1

  • Plate Current

    9 mA

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.3 Current

    0.17 mA

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.l Voltage (Approx.) for transconductance of

    100 µS

    Published in approved 12FQ7 target entry; Section1

  • Grid-No.l Voltage (Approx.) for transconductance of 100 /imhos

    -5 V

    Published in approved 12FQ7 target entry; Section1