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Voltage Pentode or Tetrode (under 100V) ·Pentode

DF65

Low-power directly heated subminiature AF pentode for hearing aids. Philips documentation places it in very-low-current battery audio service, closely related to the DF67 family and optimized for compact portable amplification.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
SUBMINIATURE
Socket code
WIRE8
Base pins
8
Nominal heater
0.625 V / 15 mA

Description

Low-power directly heated subminiature AF pentode for hearing aids; its sheet cross-references the DF67 family.

Socket description

Subminiature all-glass 8-wire lead family

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
SUBMINIATURE
Socket code
WIRE8
Base pins
8
Nominal heater voltage
0.625 V
Nominal heater current
15 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

SUBMINIATURE - 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
Plate resistance
4000000 Ω
Transconductance
0.0001 S
Max plate voltage
45 V
Max screen voltage
45 V

Subminiature AF pentode for hearing-aid service.

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

1963 Philips Electron Tubes Handbook V1

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

  • Control-grid capacitance

    1.6 pF

  • Plate capacitance

    2.2 pF

  • Grid-to-plate capacitance

    0.15 pF

Other

  • Plate voltage

    22.5 V

    HearingAid

  • Screen voltage

    22.5 V

    HearingAid

  • Plate current

    50 uA

    HearingAid

  • Screen current

    15 uA

    HearingAid

  • Grid voltage

    -1.05 V

    HearingAid

Characteristic

  • Transconductance

    100 uS

Data set 02

1999 Philips 0-D

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

  • Input capacitance

    1.5 pF

  • Output capacitance

    1.5 pF

  • Plate-grid capacitance maximum

    0.2 pF

Characteristics

  • Plate voltage

    22.5 V

  • Screen voltage

    18 V

  • Plate current

    0.05 mA

  • Screen current

    0.01 mA

  • Grid bias

    -1.15 V

  • Transconductance

    100 uS

  • Plate resistance

    4 Mohm

  • Screen-grid amplification factor

    8.7