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Tube Tinker — Electron Tube Database
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Specialized - Cathode Ray ·CathodeRay

21EYP4

Twenty-one-inch direct-view monochrome television picture tube with magnetic deflection and high-voltage operation. Manufacturer documentation describes its focusing system, picture-screen construction, and receiver-display characteristics for large-screen television service.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
12L
Socket code
-
Base pins
6
Nominal heater
6.3 V / 600 mA

Description

Sylvania 21EYP4 direct-view monochrome television CRT with electrostatic focus, magnetic deflection, and Aluminized P4 white. Published high-voltage ratings, focus/cutoff ranges, capacitances, and typical operating conditions were extracted.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
12L
Socket code
-
Base pins
6
Nominal heater voltage
6.3 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

12L - 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

Cathode Ray

X-ray radiationInterelectrode capacitances
Max plate voltage
22000 V

CRT maximum accelerating/anode/ultor voltage is promoted to MaxPlateVoltage; additional electrode ratings, capacitances, operating conditions, focus/deflection and optical data are 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

1965 Sylvania Electronic Tubes Vol3

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristic

  • Heater Voltage

    6.3 V

  • Heater Current

    600 mA

  • FocusingMethod

    Electrostatic

  • DeflectionMethod

    Magnetic

  • Phosphor

    Aluminized P4 white

  • DeflectionAngles

    67H/53V/72D

  • Cathode To All Capacitance

    5 pF

  • Grid1 To All Capacitance

    6 pF

  • ExternalConductiveCoatingToAnodeCapacitanceMaximum

    2500 pF

  • ExternalConductiveCoatingToAnodeCapacitanceMinimum

    2000 pF

Other

  • AnodeVoltageMaximum

    22000 V

  • AnodeVoltageMinimum

    10000 V

  • FocusingElectrodeVoltageRangeMaximum

    -550 to +1100 V

  • Grid2VoltageMaximum

    700 V

  • Grid2VoltageMinimum

    350 V

  • Grid1NegativeBiasMagnitudeMaximum

    155 V

  • Grid1PositivePeakVoltageMaximum

    2 V

  • HeaterCathodeVoltageMaximum

    450 V

    Warmup<=15s;HeaterNegative

  • HeaterCathodeVoltageMaximum

    200 V

    AfterWarmup

  • HeaterCathodeVoltageMaximum

    200 V

    HeaterPositive

  • Anode Voltage

    18000 V

  • FocusingElectrodeVoltage

    0 to +400 V

  • Grid1VoltageForCutoff

    -35 to -72 V

  • Grid1CircuitResistanceMaximum

    1.5 Mohm

Data set 02

1971 RCA HB3 Binder 1 of 7

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristic

  • Heater current

    60 mA

    At6.3V

Capacitance

  • Cathode to all other electrodes

    5 pF

  • External conductive coating to anode capacitance

    - to 1500 pF

Other

  • Minimum anode/ultor voltage

    12000 V

  • Maximum grid 2 voltage

    700 V

  • Maximum grid 1 negative-bias voltage

    180 V

    NegativeBias

  • Maximum grid 1 positive-bias voltage

    0 V

    PositiveBias

  • Maximum grid 1 positive-peak voltage

    2 V

    PositivePeak

  • Maximum grid 1 negative-peak voltage

    220 V

    NegativePeak

  • Peak heater-cathode voltage

    200 V

    HeaterNegativeOperating

  • Peak heater-cathode voltage

    200 V

    HeaterPositive

  • Projected screen area

    262 in^2

  • Typical anode/ultor voltage

    18000 V