Data set 01
1951 Mullard Valve and Service Manual
Published operating points and test conditions from this source.
SECTION 1
Pentode
Application
Service
Audio power output
Power - Pentode (NOT beam) ·Pentode
EL31
25 W output pentode for high-power push-pull audio amplifiers and power-triode driver stages.
Directly heatedCold cathodeCommon cathodeDissimilar
- Sections
- 1
- Base
- Octal
- Socket code
- IO
- Base pins
- 8
- Nominal heater
- 6.3 V / 1.4 A
Description
25-watt output pentode for high-power audio amplifiers, especially push-pull stages. Published heater, characteristics, ratings and application information were read from the supplied Mullard sheet.
Socket description
International Octal
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- Octal
- Socket code
- IO
- Base pins
- 8
- Nominal heater voltage
- 6.3 V
- Nominal heater current
- 1.4 A
- Parallel heater voltage
- -
- Parallel heater current
- -
- Series capable
- No
Octal - 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
- 20000 Ω
- Transconductance
- 0.014 S
- Amplification factor
- 16.5
- Max plate voltage
- 800 V
- Max screen voltage
- 400 V
- Max plate dissipation
- 25 W
- Max screen dissipation
- 8 W
- Max cathode current
- 200 mA
rp/gm promoted from published 275 V point; maximum ratings from limiting-values table.
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
1958 Mullard Receiving Tubes
Published operating points and test conditions from this source.
SECTION 1
Pentode
Characteristics
Plate voltage
275 V
Point1
Screen-grid voltage
275 V
Point1
Plate current
91 mA
Point1
Transconductance
14000 uS
Point1
Plate resistance
20 kOhm
Point1
Other
Output power
84 W
ClassAB;PushPull;TwoTubes;FixedBias;Va=600V
Output power
120 W
ClassAB;PushPull;TwoTubes;FixedBias;Va=800V
Data set 03
1963 Mullard
Published operating points and test conditions from this source.
SECTION 1
Pentode
Characteristic
Anode current
42 mA
Va=600V; Vg2=400V
Screen current
5 mA
Va=600V; Vg2=400V
Other
Output power
25 W
SingleValve; Va=275V; Vg2=275V