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Voltage Pentode - Sharp Cutoff (single) ·Pentode

1AE4

Directly heated high-slope pentode for low-voltage RF and general voltage amplification in portable battery equipment.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 6AR
Socket code: B7G
Base pins: 7
Nominal heater: 1.25 V / 100 mA

Description

1AE4 — Sharp-Cutoff RF Pentode

The 1AE4 is a miniature, filament-type sharp-cutoff pentode designed primarily for radio frequency (RF) amplification in portable electronic equipment. Featuring a directly heated cathode (filament) and a 7-pin miniature construction, the tube is optimized for low-power, battery-operated applications. It is housed in a small T-5 1/2 glass envelope and can be operated in any mounting position.

Mechanical Construction and Physical Dimensions

The 1AE4 is constructed using a miniature button 7-pin base (JEDEC E7-1 or 7 C 10) and a T-5 1/2 glass bulb (also designated as A 19-2). The physical dimensions of the tube are highly compact, making it suitable for portable layouts:

Maximum Diameter: 3/4 inch (approximately 19 mm)
Maximum Seated Height: 1 7/8 inches
Maximum Overall Length: 2 1/8 inches (approximately 47.6 mm)
Maximum Pin Length: 7.14 mm

The tube is designed to operate in any mounting position.

Filament and Power Requirements

The 1AE4 features a directly heated filament designed for parallel DC supply operation. The nominal filament ratings are:

Filament Voltage (DC): 1.25 V
Filament Current: 0.1 A (100 mA)

Depending on the rating system applied, the permissible filament voltage tolerances are specified as:

Design Center System: 1.25 V ± 0.19 V (or 1.25 V ± 15%)
Absolute Maximum System: 1.00 V minimum to 1.50 V maximum

Pinout and Terminal Connections

The 1AE4 uses a 7-pin miniature base configuration, typically designated as JEDEC 6AR (or 8YA in some indexing systems). The bottom-view pin connections are as follows:

Pin	Connection
Pin 1	Filament negative (F-), Grid No. 3 (G3)
Pin 2	Plate (P) / Anode
Pin 3	Grid No. 2 (G2) / Screen Grid
Pin 4	No Connection (NC) *
Pin 5	Filament negative (F-), Grid No. 3 (G3)
Pin 6	Grid No. 1 (G1) / Control Grid
Pin 7	Filament positive (F+)

* Note: While most standard pinout diagrams specify Pin 4 as having no connection (with the suppressor grid, Grid No. 3, internally connected to the negative filament at Pins 1 and 5), some documentation lists Pin 4 as Grid No. 3.

Electrical Capacitances

When measured with an external shield (such as shield #313 or #316), the direct interelectrode capacitances of the 1AE4 are:

Grid No. 1 to Plate (maximum): 0.008 pF (also expressed as 8 mpF)
Input Capacitance: 3.6 pF
Output Capacitance: 4.4 pF

These low capacitances, particularly the extremely low grid-to-plate feedback capacitance, are characteristic of its design as a sharp-cutoff RF pentode, helping to prevent instability and oscillation in high-frequency amplifier stages.

Maximum Ratings

The maximum operating limits for the 1AE4 are defined under two different rating systems in historical technical literature. Designers must adhere to these limits to ensure reliable operation.

Design Center System

Filament Voltage (DC): 1.25 ± 0.19 V
Maximum Plate Voltage: 90 V
Maximum Grid No. 2 (Screen) Voltage: 90 V
Maximum Grid No. 1 (Control Grid) Voltage (Negative-bias): 50 V
Maximum Grid No. 1 (Control Grid) Voltage (Positive-bias): 0 V
Maximum Total Cathode Current: 11 mA

Absolute Maximum System

Filament Voltage: 1.00 V to 1.50 V
Maximum Anode (Plate) Voltage: 100 V
Maximum Grid No. 2 Voltage: 100 V
Maximum Grid No. 1 Voltage (Negative-bias): 50 V
Maximum Grid No. 1 Voltage (Positive-bias): 0 V
Maximum Average Cathode Current: 11 mA

Typical Operating Conditions and Characteristics

In typical Class A1 (or Class A) RF amplifier service, the 1AE4 operates under the following nominal conditions:

Parameter	Value
Plate (Anode) Voltage	90 V
Grid No. 2 (Screen) Voltage	90 V
Grid No. 1 (Control Grid) Voltage	0 V
Plate Current	3.5 mA
Grid No. 2 Current	1.0 mA to 1.2 mA
Plate Resistance	0.5 MΩ (500,000 Ω)
Transconductance (Mutual Conductance)	1550 µmhos (1.55 mA/V)
Grid No. 1 Cutoff Voltage (approx. for Ib = 50 µA)	-5 V

The high plate resistance of 0.5 MΩ combined with a transconductance of 1550 µmhos allows the tube to provide stable voltage gain in RF and IF stages when coupled with appropriate tuned circuits. The sharp-cutoff characteristic is demonstrated by the plate current dropping to a mere 50 µA when the control grid bias is decreased to approximately -5 V.

Technical Summary

The 1AE4 is a compact, 7-pin miniature sharp-cutoff pentode designed for low-power RF amplification in portable, battery-operated equipment. Operating with a 1.25 V, 100 mA DC filament, it provides a transconductance of 1550 µmhos and a high plate resistance of 0.5 MΩ at a typical operating point of 90 V on both the plate and screen grid. Its physical design, low interelectrode capacitances, and low power consumption make it highly optimized for portable receiver applications.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 6AR
Socket code: B7G
Base pins: 7
Nominal heater voltage: 1.25 V
Nominal heater current: 100 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

6AR - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1G3	A	G3 — Suppressor GridGroup 6AR1 Original EIA label G3; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN1IS	A	IS — Internal ScreenGroup 6AR1 Original EIA label IS; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN1F	—	F — FilamentGroup 6AR1 Original EIA label F; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN2P	A	P — Plate (Anode) Original EIA label P; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN3G2	A	G2 — Screen Grid Original EIA label G2; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN4IC	—	IC Original EIA label IC; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN5G3	A	G3 — Suppressor GridGroup 6AR5 Original EIA label G3; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN5IS	A	IS — Internal ScreenGroup 6AR5 Original EIA label IS; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN5F	—	F — FilamentGroup 6AR5 Original EIA label F; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN6G1	A	G1 — Control Grid Original EIA label G1; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR
PIN7F	—	F — Filament Original EIA label F; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 127, 6AR

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 500000 Ω
Transconductance: 0.00155 S
Max plate voltage: 390 V
Max screen voltage: 90 V
Max cathode current: 11 mA

Sharp-cutoff RF pentode.

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

1938 Raytheon

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Filament Voltage (dc)
15 volts
Filament Voltage (dc) 1.25£15% volts
Plate Voltage
90 volts
Plate Voltage 90 volts ohen
Grid #
6 volts
Grid #2 Voltage 90 volts 2 an=a | 6
Negative —Bias Value
50 volts
Negative —Bias Value 50 volts
Positive —Bias Value
0 volts
Positive —Bias Value 0 volts
Total Cathode Current
7 ma
Total Cathode Current 11 ma. | 7

Characteristics

Filament Voltage (dc)
15 volts
Filament Voltage (dc) 1.25+15% volts
Filament Current
0.1 amps
Filament Current 0.1 amps,
Plate Voltage
90 volts
Plate Voltage 90 volts
Grid #
6 volts
Grid #2 Voltage 90 volts 6AR
Grid #
0 volts
Grid #1 Voltage 0 volts
Plate Resistance
0.5 meg
Plate Resistance 0.5 meg.
Transconductance
1550 pmhos
Transconductance 1550 pmhos
Plate Current
3.5 ma
Plate Current 3.5 ma.
Grid #
1.2 ma
Grid #2 Current 1.2 ma.
Grid #
-5 volts
Grid #1 Voltage (approx. for Ib=50 pa.) -5 volts

Data set 02

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

Input capacitance
3.6 pF
Output capacitance
4.4 pF
Grid-to-plate capacitance
0.008 pF

Other

Plate voltage
90 V
ClassA
Screen voltage
90 V
ClassA
Grid voltage
0 V
ClassA
Plate current
3.5 mA
ClassA
Screen current
1.2 mA
ClassA

Data set 03

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate voltage
90 V
ClassA
Grid 2 voltage
90 V
ClassA

Capacitance

Grid 1 to plate
0.008 pF

Data set 04

1966 Tung Sol Electronic Tubes 1 of 4

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Filament voltage
1.25 V
DC
Filament current
100 mA
Plate voltage
90 V
ClassA
Screen voltage
90 V
ClassA
Plate current
6.5 mA
ClassA

Characteristic

Transconductance
2600 uS
ClassA

Capacitance

Output capacitance
4.4 pF
ExternalShield

Data set 05

1968 Mazda Belvu

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristics

Heater or filament voltage
1.25 V
Published nominal value
Heater or filament current
100 mA
Published nominal value
Transconductance
1550 µS
Published operating characteristic

Capacitance

Input capacitance
3.6 pF
With external shielding
Output capacitance
4.4 pF
With external shielding