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Voltage - Triode (with diode, heptode or hexode) ·Diode-Diode-Triode

303A

Western Electric double-diode triode combining two rectifying elements with a medium-mu voltage-amplifier section. The paired diodes provide detector or signal rectification while the triode supplies subsequent gain.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
3
Base
-
Socket code
UX4
Base pins
4
Nominal heater
2 V / 1.6 A

Description

Duodiode triode with indirectly heated common cathode.

Socket description

Medium-shell UX 4-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
UX4
Base pins
4
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

3 physical sections, each with unique specifications.

Section 1

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Promoted fields audited from printed ratings/characteristics; remaining published values preserved as parameters.

Section 2

Diode

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Promoted fields audited from printed ratings/characteristics; remaining published values preserved as parameters.

Section 3

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
17000 Ω
Amplification factor
14.1
Max plate voltage
200 V

Promoted fields audited from printed ratings/characteristics; remaining published values preserved as parameters.

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 300s

Published operating points and test conditions from this source.

SECTION 1

Diode

Characteristic

  • Heater voltage

    2 volt

    Heater voltage 2.0 volts, a.c. or d.c.

  • Nominal heater current

    1.6 amperes

    Nominal heater current 1.60 amperes

  • tube are shown in Figure

    3 volt

    tube are shown in Figure 3 as functions of grid bias for several values of plate voltage. Corresponding

  • amplification-factor, plate-resistance, and transconductance characteristics are given in Figures

    4

    amplification-factor, plate-resistance, and transconductance characteristics are given in Figures 4,

  • Published value

    5 volt

    5, and 6 respectively. Plate current characteristics as functions of plate voltage for several values

  • included within the area, ABCD, in Figure

    3

    included within the area, ABCD, in Figure 3. Values of amplification factor and plate resistance

  • ponding power output, Pm, in milliwatts, and the second and third harmonic levels, F

    2 watts

    ponding power output, Pm, in milliwatts, and the second and third harmonic levels, F2m and Fgm,

  • the level of the third harmonic is lower than

    45

    the level of the third harmonic is lower than 45 db below the fundamental, its value may be widely

  • levels of individual tubes extends from

    20 volt

    levels of individual tubes extends from 20 to 64 db below 1 volt. Since microphonic noise output

  • Diode Characteristics—The current-voltage characteristic of a single diode is shown in Figure

    8 volt

    Diode Characteristics—The current-voltage characteristic of a single diode is shown in Figure 8.

  • voltage. Load lines for zero fixed bias are shown in Figure

    9 volt

    voltage. Load lines for zero fixed bias are shown in Figure 9 for load resistance values of 0.25,

Other

  • voltage should be limited to a maximum value of +

    10 volt

    voltage should be limited to a maximum value of +10 volts. Rectification characteristics for a

SECTION 3

Triode

Characteristic

  • Triode Microphonic Noise—With a plate voltage of

    135 volt

    Triode Microphonic Noise—With a plate voltage of 135 volts, a grid bias of — 6 volts, and a

  • load resistance of

    100000 ohms

    load resistance of 100,000 ohms, the mean microphonic noise output level of the triode section of