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Voltage - Dual Triode (similar) ·Triode-Triode

7025

Special-quality high-mu twin triode designed as a low-noise voltage amplifier, with documented low equivalent noise for sensitive audio and low-level signal applications.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: 9A
Socket code: B9A
Base pins: 9
Nominal heater: 12.6 V / 150 mA

Description

7025 is a DualTriode vacuum tube documented in the RCA Receiving Tube Manual. The supplied excerpt was reviewed for heater data, section arrangement, maximum ratings, electrical characteristics, interelectrode capacitances, typical operating conditions, and stated applications.

Socket description

Small-button Noval 9-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 9A
Socket code: B9A
Base pins: 9
Nominal heater voltage: 12.6 V
Nominal heater current: 150 mA
Parallel heater voltage: 6.3 V
Parallel heater current: 300 mA
Series capable: Yes

9A - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN12P	B	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN22G1	B	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN32K	B	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN4H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN5H	—	H — Heater EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN61P	A	P — Plate (Anode) EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN71G1	A	G1 — Control Grid EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN81K	A	K — Cathode EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A
PIN9HCT	—	HCT — Heater Center Tap EIA transcription; manufacturer confirmation pending	Unverified EIA Base Connections, printed page 130, 9A

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 62500 Ω
Transconductance: 0.0016 S
Amplification factor: 100
Max plate voltage: 300 V
Max plate dissipation: 1 W
Max cathode current: 8 mA

Representative row for two electrically identical sections; promoted characteristics use the 250-V Class-A point.

Section 2

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 62500 Ω
Transconductance: 0.0016 S
Amplification factor: 100
Max plate voltage: 300 V
Max plate dissipation: 1 W
Max cathode current: 8 mA

Second physical triode section; added to align rows with SectionCount.

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

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Heater Voltage
12.6 V
Heater Current
150 mA

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Heater voltage
12.6 V
Nominal
Heater current
150 mA
Nominal
Plate voltage
100 V
ClassA; OperatingPoint1
Grid voltage
-1 V
ClassA; OperatingPoint1
Plate voltage
250 V
ClassA; OperatingPoint2
Grid voltage
-2 V
ClassA; OperatingPoint2
Equivalent noise and hum voltage average
1.8 uV RMS
Published test conditions
Equivalent noise and hum voltage maximum
7 uV RMS
Published test conditions

Characteristic

Plate current
0.5 mA
ClassA; OperatingPoint1
Amplification factor
100
ClassA; OperatingPoint1
Plate resistance
80000 ohm
ClassA; OperatingPoint1
Transconductance
1250 uS
ClassA; OperatingPoint1
Plate current
1.2 mA
ClassA; OperatingPoint2
Amplification factor
100
ClassA; OperatingPoint2
Plate resistance
62500 ohm
ClassA; OperatingPoint2
Transconductance
1600 uS
ClassA; OperatingPoint2

Data set 03

1963 Amperex Condensed

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Heater/filament voltage
6.3 V
Published rating
Heater/filament current
300 mA
Published rating
Series heater voltage
12.6 V
SeriesHeater
Series heater current
150 mA
SeriesHeater
Amplification factor
100
VoltageAmplifier
Plate resistance
62500 ohm
VoltageAmplifier
Transconductance
1600 µS
VoltageAmplifier

Other

Plate voltage
250 V
VoltageAmplifier
Control-grid bias
-2 V
VoltageAmplifier
Plate current
1.2 mA
VoltageAmplifier

Data set 04

1965 Sylvania Electronic Tubes Vol3

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

Series heater voltage
12.6 V
SeriesHeater
Series heater current
150 mA
SeriesHeater
Parallel heater voltage
6.3 V
ParallelHeater
Parallel heater current
300 mA
ParallelHeater
Transconductance low
1250 uS
Transconductance high
1600 uS

Other

Plate voltage maximum
300 V
Typical plate voltage low
100 V
ClassA
Typical plate voltage high
250 V
ClassA

CrossReference

Equivalent type
12AX7

Application

Application
Low-noise voltage amplifier

Data set 05

1966 Tung Sol Electronic Tubes 4 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Heater voltage
6.3 V
Nominal
Heater current
300 mA
Nominal
Maximum plate voltage
300 V
Promoted published value
Maximum plate dissipation
1 W
Promoted published value
a MAXIMUM HEATER —CATHODE VOLTAGE 1$O VOLTS
1 V
RATINGS
MAXIMUM PLATE VOLTAGE 3OO VOLTS
3 V
RATINGS
MAXIMUM NEGATIVE DC GRID VOLTAGE -5O VOLTS
-5 V
RATINGS
PLATE CURRENT O.5 I.
2 mA
CLASS A1,AMPLIFIER - EACH SECTION
AMPLIFICATION FACTOR 1GG lUU
1 A
CLASS A1,AMPLIFIER - EACH SECTION
PLATE RESISTANCE $O GQG E)Z 5OO OHMS
5 ohm
CLASS A1,AMPLIFIER - EACH SECTION
HEATER VOLTAGE (PARALLEL CONNECTIONJ~ 6.J VOLTS AC, CENTER
6 V
ADDITIONAL CHARACTERISTICS

Characteristic

Plate resistance
62500 ohm
Promoted published value
Transconductance
1600 uS
Promoted published value
Amplification factor
100
Promoted published value
AND AMPLIFIER COVERING FREQUENCY RANGE BETWEEN 25 &10000 CRS.
10000 A
ADDITIONAL CHARACTERISTICS

Data set 06

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Plate Resistance
80000 ohm
ClassA;Ep=100V
Transconductance
1250 uS
ClassA;Ep=100V
Equivalent Noise and Hum Voltage Average
1.8 uV
Equivalent Noise and Hum Voltage Maximum
7 uV

Data set 07

1971 RCA HB3 Binder 5 of 7

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Heater voltage
12.6 V
Heater current
150 mA
Heater voltage series
12.6 V
Heater current series
150 mA
Heater voltage parallel
6.3 V
Heater current parallel
300 mA
Plate voltage
250 V
ClassA;EachSection
Grid voltage
-2 V
ClassA;EachSection
Plate current
1.2 mA
ClassA;EachSection
Equivalent noise average
1.8 uV RMS
Audio
Equivalent noise maximum
7 uV RMS
Audio

Characteristic

Plate resistance
62500 ohm
EachSection
Transconductance
1600 uS
EachSection
Amplification factor
100
EachSection

Capacitance

Grid-to-plate capacitance
1.7 pF
EachSection

Data set 08

2026 JJ Electronic

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Ik
8 mA
Published value
Ub
250
Published value
Ra
47
Published value
Rg
150
Published value
Rk
1.2
Published value

Characteristics

Ua
250 V
Published value
Ug
-2 V
Published value
Ia
1.2 mA
Published value
S
1600 µS
Published value
Ri
62.5 kΩ
Published value
µ
100
Published value

Capacitance

cg/k
1.6
Published value
ca
0.33
Published value
cg/a
1.7
Published value