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Voltage Pentode - Remote Cutoff (single) ·Pentode

286A

Western Electric variable-mu suppressor-grid pentode for high-frequency or audio-frequency voltage amplification and modulation. Its controlled characteristic permits gain variation while supporting a broader range of signal and modulation applications.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
MEDIUM6
Base pins
6
Nominal heater
2 V / 1.6 A

Description

Variable-mu voltage-amplifier suppressor-grid pentode with indirectly heated cathode for high-frequency or audio-frequency amplification and modulation.

Socket description

Medium 6-contact base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
MEDIUM6
Base pins
6
Nominal heater voltage
2 V
Nominal heater current
1.6 A
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
700000 Ω
Transconductance
0.0012 S
Amplification factor
850
Max plate voltage
250 V
Max screen voltage
75 V
Rectifier max heater-cathode voltage
90 V

Typical characteristics at Eb=180 V, Ec2=75 V, Ec3=0 V, Ec1=-1.5 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

2026 Western Electric 200s

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate Current

    6.2 mA

    Eb=180V

  • Screen Grid Current

    1.6 mA

    Eb=180V

Capacitance

  • Control Grid to Plate Capacitance

    0.004 pF

  • Suppressor Grid to Plate Capacitance

    1.7 pF

  • Plate to Heater Cathode and Screen Grid Capacitance

    12.2 pF

  • Control Grid to Suppressor Grid Capacitance

    0.06 pF

  • Control Grid to Heater Cathode and Screen Grid Capacitance

    6.3 pF

  • Suppressor Grid to Heater Cathode and Screen Grid Capacitance

    7 pF