DF64

Mullard subminiature AF voltage-amplifying pentode designed for hearing aids and extremely low-power battery operation. Its directly heated miniature construction minimizes heater demand for compact portable audio equipment.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: SUBMINIATURE
Socket code: WIRE8
Base pins: 8
Nominal heater: 0.625 V / 10 mA

Description

The Mullard DF64 is a subminiature AF voltage-amplifying pentode for hearing aids and very low-power battery operation.

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: 10 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: 1000000 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 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

Filament Voltage
0.62 V
Filament Current
10 mA
Plate Voltage
15 V
Screen Voltage
15 V
Plate Current
0.05 mA
Screen Current
0.017 mA
Grid Voltage
-0.75 V
Transconductance
90 uS
Plate Resistance
1200000 ohm

Other

Stage Gain
27.4 dB
ResistanceCoupled; FixedBias
Stage Gain
28 dB
ResistanceCoupled; GridCurrentBias
Maximum Plate Voltage
45 V
Maximum Screen Voltage
45 V
Maximum Cathode Current
0.075 mA

Data set 02

1963 Philips Electron Tubes Handbook V1

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

Control-grid capacitance
1.8 pF
Plate capacitance
2 pF
Grid-to-plate capacitance
- to 0.2 pF

Other

Plate voltage
15 V
HearingAid
Screen voltage
15 V
HearingAid
Plate current
60 uA
HearingAid
Screen current
20 uA
HearingAid
Grid voltage
-0.62 V
HearingAid

Characteristic

Transconductance
100 uS
Plate resistance
1 Mohm

Data set 03

1999 Philips 0-D

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

Input capacitance
1.8 pF
Output capacitance
2 pF
Plate-grid capacitance maximum
0.2 pF

Characteristics

Plate voltage
19 V
Screen voltage
15 V
Plate current
60 uA
Screen current
20 uA
Grid bias
-0.62 V
Transconductance
100 uS
Plate resistance
1 Mohm