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Voltage - Triode (single high frequency) ·Triode

4211D

Directly heated replacement triode; the E version adds small grid and anode lead chokes to suppress spurious ultra-high-frequency oscillation.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
LARGE4BAYONET
Base pins
4
Nominal heater
10 V / 3 A

Description

Directly heated triode. For replacement purposes only. The 421 I -E valve is similar to 421 I -D valve but has small chokes (approx- imately one microhenry) connected in series with the grid and anode leads to prevent spurious oscillations at ultra high freque

Socket description

Large 4-contact bayonet base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
LARGE4BAYONET
Base pins
4
Nominal heater voltage
10 V
Nominal heater current
3 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

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
3000 Ω
Transconductance
0.004 S
Amplification factor
12
Max plate voltage
1000 V
Max plate dissipation
65 W
Max cathode current
200 mA

Published ratings and characteristics promoted where directly established by the datasheet.

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

1946 Standard Telephone and Cables

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Mutual conductance

    4000 µS

    Published characteristic; normalized from mA/V

Other

  • Grid-anode capacity

    8.9 pF

    Published interelectrode capacitance

  • Grid-filament capacity

    69 pF

    Published interelectrode capacitance

  • Maximum direct anode current

    200 mA

    Maximum safe operating rating