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Power - Pentode Single (NOT beam) (under 10W) ·Pentode

25A6G

Power/output pentode designed for Class-A, single-ended, or push-pull audio-frequency output amplification.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: IO
Base pins: 7
Nominal heater: 25 V / 300 mA

Description

Power pentode for AC/DC receiver output service.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: IO
Base pins: 7
Nominal heater voltage: 25 V
Nominal heater current: 300 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: 42000 Ω
Transconductance: 0.002375 S
Amplification factor: 90
Max plate voltage: 180 V
Max screen voltage: 135 V
Max plate dissipation: 4.3 W
Max screen dissipation: 1.9 W

Electrical section reconstructed from published ratings/characteristics; promoted transconductance normalized to A/V.

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

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Max, Plate Voltage
180 V
Published ratings
Max, Screen Voltage
135 V
Published ratings
Plate Voltage
95 V
ClassA; Column1
Plate Voltage
135 V
ClassA; Column2
Plate Voltage
180 V
ClassA; Column3
Screen Voltage
95 V
ClassA; Column1
Screen Voltage
135 V
ClassA; Column2
Screen Voltage
135 V
ClassA; Column3
r‘an §V Grid Bias
-15 V
ClassA; Column1
r‘an §V Grid Bias
-20 V
ClassA; Column2
r‘an §V Grid Bias
-20 V
ClassA; Column3
MAK *k Amplification Factor (approxy
90
ClassA; Column1
MAK *k Amplification Factor (approxy
85
ClassA; Column2
MAK *k Amplification Factor (approxy
100
ClassA; Column3
e Plate Resistance {approx
45000
ClassA; Column1
e Plate Resistance {approx
35000
ClassA; Column2
e Plate Resistance {approx
40000
ClassA; Column3
Plate Current
20 mA
ClassA; Column1
Plate Current
37 mA
ClassA; Column2
Plate Current
38 mA
ClassA; Column3
PR L Load Resistance
4500 ohm
ClassA; Column1
PR L Load Resistance
4000 ohm
ClassA; Column2
PR L Load Resistance
5000 ohm
ClassA; Column3
Total Harmonic Distortion
11 %
ClassA; Column1
Total Harmonic Distortion
9 %
ClassA; Column2
Total Harmonic Distortion
10 %
ClassA; Column3
Dw[] *l\N' Power Output
0.9 W
ClassA; Column1
Dw[] *l\N' Power Output
2 W
ClassA; Column2
Dw[] *l\N' Power Output
2.75 W
ClassA; Column3
Heater to cathode bies should not exceed
90
ClassA

Data set 02

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

HeaterOrFilamentVoltage
25 V
HeaterOrFilamentCurrent
300 mA

Other

Power Output
2.2 W
ClassA;PlateVoltage=160V

Data set 03

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Pentode

Application

Service
Audio power output

Data set 04

1958 Brimar Radio Valve No 7

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Power output maximum published
2.2 W

Data set 05

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate Voltage
160 V
ClassA
Screen Voltage
120 V
ClassA
Power Output
2.2 W
ClassA
Load Resistance
5000 ohm
ClassA