DF61

Subminiature battery RF pentode for amplification and frequency-changer service. Its 1.25 V, 25 mA filament and very high plate resistance provide useful signal gain and converter operation with exceptionally low filament consumption.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: WIRE8
Base pins: 8
Nominal heater: 1.25 V / 25 mA

Description

The Mullard DF61 is a subminiature RF pentode for battery-operated receivers and frequency-changer service.

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: 1.25 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: 1600000 Ω
Transconductance: 0.00095 S
Max plate voltage: 90 V
Max screen voltage: 67.5 V
Max cathode current: 2.5 mA

Published Mullard/Philips ratings and characteristics promoted where applicable; additional values retained as parameters.

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

1958 Mullard Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Pentode

Application

Application
RF amplifier / frequency changer

Data set 02

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

Filament Voltage
1.25 V
DCOnly
Filament Current
25 mA
DCOnly
Plate Voltage
67.5 V
Screen Voltage
67.5 V
Plate Current
1.7 mA
Screen Current
0.45 mA
Transconductance
950 uS
Plate Resistance
1600000 ohm
Input Capacitance
3.1 pF
Output Capacitance
3.6 pF
Plate-Grid Capacitance
0.01 pF
Maximum

Other

Conversion Transconductance
290 uS
FrequencyChanger; Va=67.5V
Maximum Plate Voltage
90 V
Maximum Screen Voltage
67.5 V
Maximum Cathode Current
2.5 mA