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20A

Mesh-plate medium-gain directly heated driver triode for signal or driver amplification.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: UX4
Socket code: -
Base pins: -
Nominal heater: 5 V / 1.4 A

Description

Mesh-plate medium-gain directly heated driver triode. The supplied Emission Labs sheet was read for filament data, maximum ratings, representative operating points, gm/rp/mu, output conditions, capacitances, and rectifier filter conditions as applicable.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: UX4
Socket code: -
Base pins: -
Nominal heater voltage: 5 V
Nominal heater current: 1.4 A
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

UX4 - 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

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 3700 Ω
Transconductance: 0.0042 S
Amplification factor: 21
Max plate voltage: 490 V
Max plate dissipation: 11 W
Max cathode current: 40 mA

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 Emission Labs

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

Filament voltage
5 V
Filament current
1.4 A
Factory test plate voltage
400 V
Factory test plate current
25 mA
Factory test grid voltage
-7.4 V
Plate resistance
3700 ohm
Amplification factor
21
Transconductance
4200 uS

Other

Driver output voltage
60 V RMS
PlateVoltage=350V;PlateCurrent=10mA