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Voltage Radio Detector Converter ·Diode-Diode-Pentode

2B7

Double-diode pentode combining detector, AVC, and voltage-amplifier functions in early AC receivers. Two diodes provide signal and control rectification while the pentode supplies subsequent amplification.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 3
Base: 7D
Socket code: UX7
Base pins: 7
Nominal heater: 2.5 V / 800 mA

Description

Duplex-diode semiremote-cutoff pentode combining detector diodes with a variable-mu pentode amplifier.

Socket description

Small 7-contact (0.75-inch pin circle)

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 7D
Socket code: UX7
Base pins: 7
Nominal heater voltage: 2.5 V
Nominal heater current: 800 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

7D - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1IS	A	IS — Internal Screen EIA transcription; manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D
PIN2H	—	H — Heater EIA transcription; manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D
PIN32P	B	P — Plate (Anode) EIA transcription; manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D
PIN42K	B	K — Cathode EIA chart transcription; independent manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D
PIN51P	A	P — Plate (Anode) EIA chart transcription; independent manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D
PIN7H	—	H — Heater EIA chart transcription; independent manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D
PIN81K	A	K — Cathode EIA chart transcription; independent manufacturer verification pending	Unverified EIA Base Connections, printed page 128, 7D

Section ratings

3 physical sections, each with unique specifications.

Section 1

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Representative row for two diode sections sharing the common cathode.

Section 2

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Physical second diode section added during approved section-structure reconciliation.

Section 3

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 600000 Ω
Transconductance: 0.001125 S
Max plate voltage: 300 V
Max screen voltage: 125 V
Max plate dissipation: 2.25 W
Max screen dissipation: 0.3 W

Promoted from the printed maximum-rating/characteristic columns; additional operating-point and capacitance data are retained in TUBE_SECTION_PARAMETER.

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

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 3

Pentode

Capacitance

Input capacitance
3.5 pF
Section1
Output capacitance
9.5 pF
Section1
Grid-to-plate capacitance
0.007 pF
Section1

Other

Plate voltage
250 V
ClassA
Screen voltage
125 V
ClassA
Control-grid voltage
-3 V
ClassA
Plate current
9 mA
ClassA
Screen current
2.3 mA
ClassA
Screen voltage
100 V
ClassA
Plate current
6 mA
ClassA
Screen current
1.5 mA
ClassA

Characteristic

Plate resistance
600000 Ω
ClassA
Transconductance
1125 µS
ClassA
Plate resistance
800000 Ω
ClassA
Transconductance
1000 µS
ClassA

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Diode

Other

MinimumDiodeCurrentPerPlate
0.8 mA
40V DC applied

SECTION 3

Pentode

Other

Screen Supply Voltage Maximum
300 V

Capacitance

Input Capacitance
3.5 pF
Output Capacitance
9.5 pF