Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Voltage Pentode ·Pentode

EF812

Special-quality low-noise pentode for professional audio amplification, combining low noise with unusually strong signal capability.

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

Description

Special-quality low-noise pentode for professional audio-frequency amplification. Technical and descriptive data are taken from the supplied English-language Mazda/Thorn-AEI datasheet.

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

B9A - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Transconductance
0.0092 S
Max plate voltage
250 V
Max screen voltage
250 V
Max plate dissipation
3 W
Max screen dissipation
1 W

Published ratings and characteristics promoted from the approved English source.

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

1973 Mazda Valves Binder 2

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Heater Voltage Vh

    6.3 V

  • Heater Current Ih

    3 A

  • Maximum Anode Voltage Va(max)

    250 V

  • Maximum Screen Voltage Vg2(max)

    250 V

Characteristic

  • $ With maximum anode dissipation 2W, maximum screen dissipation

    5 W

  • Grid 1 to Earth cmn 83 8.6

    96 pF

  • Anode to Earth cout 33 36

    46 pF

  • Grid 1 to Anode cg1-a 0.0065 0.007 0'

    8 pF

  • Grid 1 to Grid 3 cg1-g3 016 0.16

    17 pF

  • Grid 1 to Grid 2 cg1_g2 25 25

    2.5 pF

  • Grid 2 to Anode cg2-a 016 024

    42 pF

  • Grid 3 to Anode cg3-a 06 0.61

    63 pF

  • Anode Voltage Va

    170 V

  • Screen Voltage Vg2

    170 V

  • Grid Bias Voltage (Approx.) Vg1 —

    1.9 V

  • Anode Current la

    10 mA

  • Screen Current Ig2

    26 mA

  • Mutual Conductance gm

    92 mA

  • Input Capacity Working Cif(w)

    115 pF

  • ■■■■■R■■R■■■■■R\■■~~!■■■■■■■■e~~■■■

    1 V