Data set 01
1951 Mullard Valve and Service Manual
Published operating points and test conditions from this source.
SECTION 1
Pentode
Characteristics
Anode Voltage
30 V
Screen Voltage
30 V
Anode Current
0.375 mA
Screen Current
0.125 mA
Voltage Pentode or Tetrode (under 100V) ·Pentode
DF70
Directly heated Mullard subminiature AF voltage-amplifying pentode for hearing aids. Its 0.625 V, 25 mA filament is specifically suited to extremely low-power battery-operated audio equipment.
Directly heatedCold cathodeCommon cathodeDissimilar
- Sections
- 1
- Base
- -
- Socket code
- WIRE8
- Base pins
- 8
- Nominal heater
- 0.625 V / 25 mA
Description
The Mullard DF70 is a directly heated subminiature AF voltage-amplifying pentode for hearing aids, using a 0.625 V, 25 mA filament.
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
- -
- Socket code
- WIRE8
- Base pins
- 8
- Nominal heater voltage
- 0.625 V
- Nominal heater current
- 25 mA
- Parallel heater voltage
- -
- Parallel heater current
- -
- Series capable
- No
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
- 500000 Ω
- Transconductance
- 0.00022 S
- Max plate voltage
- 30 V
- Max screen voltage
- 30 V
Subminiature AF pentode.
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 02
1999 Philips 0-D
Published operating points and test conditions from this source.
SECTION 1
Pentode
Other
Typical anode voltage
30 V
Published datasheet value
Typical screen-grid voltage
30 V
Published datasheet value
Control-grid voltage
-1.85 V
Published datasheet value
Anode current
50 µA
Published datasheet value
Screen-grid current
18 µA
Published datasheet value
Maximum no-load anode voltage
- to 45 V
Published datasheet value
Maximum no-load screen-grid voltage
- to 45 V
Published datasheet value
Maximum grid circuit resistance
- to 10 MΩ
Published datasheet value
Filament voltage range
0.55 to 0.75 V
Published datasheet value
Characteristics
Transconductance
100 µS
Published datasheet value
Screen-grid amplification factor
12.5
Published datasheet value
Internal resistance
2.5 MΩ
Published datasheet value