Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Voltage Tetrode ·Tetrode

435A

High figure-of-merit amplifier tetrode for high-frequency signal amplification. Its construction emphasizes useful gain and performance at elevated radio frequencies.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
B9A
Base pins
9
Nominal heater
6.3 V / 300 mA

Description

Western Electric 435A is a high figure-of-merit tetrode with an indirectly heated cathode designed for Bell System L-3 amplifier service.

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
-
Socket code
B9A
Base pins
9
Nominal heater voltage
6.3 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

Tetrode

X-ray radiationInterelectrode capacitances
Plate resistance
13000 Ω
Transconductance
0.0155 S
Max plate voltage
190 V
Max screen voltage
160 V
Max plate dissipation
3 W
Max screen dissipation
0.75 W
Max cathode current
36 mA

Promoted from printed maximum ratings and representative typical characteristics.

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

2026 Western Electric 400s

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Capacitance

  • Grid to plate maximum without external shield

    0.03 pF

  • Input without external shield

    8.1 pF

  • Output without external shield

    3.3 pF