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21FP4D

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: -
Nominal heater: 6.3 V / 600 mA

Description

21FP4D is a picture tube using electrostatic focusing and magnetic deflection. The source specifies a P4 screen and publishes CRT accelerating/anode ratings, control and focusing-electrode limits, heater-cathode limits, capacitances, and operating or deflection characteristics.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 12L
Socket code: -
Base pins: -
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: 20000 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

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
Faceplate light transmission
74 %
Approximate

Capacitance

Grid 1 to all other electrodes
6 pF
Cathode to all other electrodes
5 pF
External conductive coating to anode capacitance
- to 750 pF

Other

Maximum grid 2 voltage
550 V
Maximum grid 1 negative-bias voltage
155 V
NegativeBias
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
Projected screen area
248 in^2
Typical anode/ultor voltage
14000 V