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Voltage Pentode or Tetrode (under 100V) ·Diode-Diode-Pentode

12F8

Low-voltage combination of two detector diodes and a remote-cutoff pentode for 12 V automobile receivers. The pentode provides controlled-gain amplification while the common-cathode diodes perform detector or AVC rectification.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
3
Base
9FH
Socket code
B9A
Base pins
9
Nominal heater
12.6 V / 150 mA

Description

12F8 combines two detector diodes and a remote-cutoff pentode on a common cathode. It is intended for AF voltage amplification, detection and AVC in automobile receivers operating directly from a 12-volt battery.

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
9FH
Socket code
B9A
Base pins
9
Nominal heater voltage
12.6 V
Nominal heater current
150 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

9FH - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

3 physical sections, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
330000 Ω
Transconductance
0.001 S
Max plate voltage
30 V
Max screen voltage
30 V

Remote-cutoff pentode.

Section 2

Diode

X-ray radiationInterelectrode capacitances
Rectifier nominal output current
1 mA

Representative of two identical detector diodes.

Section 3

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Added approved missing physical diode section row.

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

  • Heater current

    150 mA

Capacitance

  • Input capacitance

    4.5 pF

  • Output capacitance

    3 pF

SECTION 2

Diode

Other

  • Maximum average diode current

    1 mA

    EachDiode

Capacitance

  • Diode-to-diode capacitance

    0.3 pF

Data set 02

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • MAX

    12.6 V

    Published datasheet; published column 1

  • MAX

    0.15 V

    Published datasheet; published column 2

  • HEATER VOLTAGE

    12.6 V

    Maximum ratings

  • MAXIMUM HEATER —CATHODE VOLTAGE t3

    0 V

    Maximum ratings

  • MAXIMUM PLATE VOLTAGE

    30 V

    Maximum ratings

  • MAXIMUM GRID N2 VOLTAGE

    30 V

    Maximum ratings

  • xTN1G TUBE

    1 V

    Maximum ratings; published column 1

  • xTN1G TUBE

    12 V

    Maximum ratings; published column 4

  • HEATER VOLTAGE

    126 V

    Typical operating conditions

  • HEATER CURRENT

    150 mA

    Typical operating conditions

  • PLATE VOLTAGE

    12.6 V

    Typical operating conditions

  • GRID /

    2 V

    Typical operating conditions; published column 1

  • GRID /

    12.6 V

    Typical operating conditions; published column 2

  • GRID Ni VOLTAGE

    0 V

    Typical operating conditions

  • PLATE CURRENT

    1 mA

    Typical operating conditions

  • TRANSCOND UC TANCE

    1000 uS

    Typical operating conditions

  • Ef =

    12.6 V

    Typical operating conditions

  • E~Z =

    12.6 V

    Typical operating conditions

  • Et =

    12.6 V

    Typical operating conditions

  • Eb =

    12.6 V

    Typical operating conditions; published column 1

  • Eb =

    1 V

    Typical operating conditions; published column 2

  • Eb =

    1000 V

    Typical operating conditions; published column 3

  • Eb =

    0 V

    Typical operating conditions; published column 4

  • Maximum plate voltage

    30 V

    Published datasheet; promoted section value

  • Maximum screen voltage

    30 V

    Published datasheet; promoted section value

Characteristic

  • Plate resistance

    330000 ohm

    Published datasheet; promoted section value

  • Transconductance

    0.001 A/V

    Published datasheet; promoted section value

SECTION 2

Diode

Capacitance

  • DIODE TO DIODE

    0.3 pF

    Interelectrode capacitances

Other

  • MAXIMUM AVERAGE DIODE CURRENT

    1 mA

    Maximum ratings

  • AVERAGE DIODE CURRENT WITH

    1 V

    Typical operating conditions; published column 1

  • AVERAGE DIODE CURRENT WITH

    0 V

    Typical operating conditions; published column 2

  • AVERAGE DIODE CURRENT WITH

    2 V

    Typical operating conditions; published column 3

  • Maximum/average diode output current

    1 mA

    Published datasheet; promoted section value

Characteristic

  • Average diode current at 10 V applied

    2 mA

    Each diode