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Specialized - Cathode Ray ·CathodeRay

12SP7

Twelve-inch P7 long-persistence cathode-ray tube with magnetic focusing and deflection. RCA identifies oscillograph service, while later documentation supports radar-style persistent display use with blue-white fluorescence and yellow afterglow.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
-
Socket code
B12C
Base pins
-
Nominal heater
6.3 V / 600 mA

Description

Twelve-inch radar CRT with magnetic focus and deflection and long-persistence P7 screen.

Socket description

Duodecar 12-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B12C
Base pins
-
Nominal heater voltage
6.3 V
Nominal heater current
600 mA
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

Cathode Ray

X-ray radiationInterelectrode capacitances
Max plate voltage
10000 V

Cathode-ray oscillograph system with magnetic focus and deflection.

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

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Application

  • Application

    Oscillograph text

Data set 02

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Maximum Plate Voltage

    11000 V

  • Typical Anode Voltage

    9000 V

Characteristic

  • Phosphor

    P7

  • Focusing Method

    Magnetic

  • Deflecting Method

    Magnetic

Data set 03

1960 Du Mont

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

  • Heater Voltage

    6.3 V

  • Heater Current

    600 mA

  • Focusing Method

    Magnetic text

  • Deflection Method

    Magnetic text

  • Phosphor

    P7 text

  • Fluorescence

    Blue/white text

  • Persistence

    Long text

  • Deflection Angle

    55 deg

    Approximate

Data set 04

1965 Sylvania Electronic Tubes Vol3

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

  • Heater Voltage

    6.3 V

  • Heater Current

    600 mA

  • Focusing Method

    Magnetic text

  • Deflection Method

    Magnetic text

  • Fluorescence

    Blue-White text

  • Persistence

    Long text

  • Phosphorescence

    Yellow text

  • Deflection Angle

    54 deg

    Approximate

  • Screen Aluminized

    No text

  • Faceplate

    Gray Filter Glass text

  • Maximum Undeflected Spot Radius

    20 mm

Other

  • Maximum Anode Voltage

    11000 V

  • Maximum Grid2 Voltage

    450 V

  • Maximum Grid1 Negative Bias

    140 V

  • Maximum Grid1 Positive Peak

    2 V

  • Maximum Heater-Cathode Voltage

    150 V

    EitherPolarity

  • Anode Voltage

    9000 V

  • Grid2 Voltage

    250 V

  • Grid1 Cutoff Voltage Minimum

    -63 V

  • Grid1 Cutoff Voltage Maximum

    -27 V

  • Focusing Coil Current

    110 mA

    Approximate

  • Maximum Grid1 Circuit Resistance

    1.5 Mohm