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

902A

Early electrostatic cathode-ray oscillograph tube intended for observation or recording of electrical phenomena, with manufacturer-defined focusing, deflection, and fluorescent-screen characteristics for type 902A.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
8CD
Socket code
UX4
Base pins
8
Nominal heater
6.3 V / 600 mA

Description

High-vacuum green-screen cathode-ray tube with electrostatic focusing and electrostatic deflection, intended for oscilloscope and display service.

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
8CD
Socket code
UX4
Base pins
8
Nominal heater voltage
6.3 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8CD - 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

No fixed ratings are recorded for this section.

Cathode-ray section. CRT anode/ultor, grid, focus/deflection, heater-cathode, capacitance, and operating values are stored as section 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

Capacitance

  • Grid #1 to All Other Electrodes Capacitance

    7.5 pF

    Approximate

  • Deflecting Electrode DJ1 to All Other Electrodes Capacitance

    8.5 pF

    Approximate

  • Deflecting Electrode DJ4 to All Other Electrodes Capacitance

    6 pF

    Approximate

Characteristics

  • Focusing Method

    Electrostatic

  • Deflecting Method

    Electrostatic

  • Deflection Sensitivity DJ1-DJ2 at 400 V

    0.273 mm/V

  • Deflection Sensitivity DJ1-DJ2 at 600 V

    0.183 mm/V

  • Deflection Sensitivity DJ3-DJ4 at 400 V

    0.326 mm/V

  • Deflection Sensitivity DJ3-DJ4 at 600 V

    0.217 mm/V

  • Deflection Factor DJ1-DJ2 at 400 V

    93 V/in

  • Deflection Factor DJ1-DJ2 at 600 V

    139 V/in

  • Deflection Factor DJ3-DJ4 at 400 V

    78 V/in

  • Deflection Factor DJ3-DJ4 at 600 V

    117 V/in

Other

  • Anode #2 and Grid #2 Voltage

    - to 660 V

    Absolute maximum

  • Anode #1 Voltage

    - to 330 V

    Absolute maximum

  • Grid #1 Negative Voltage

    - to 125 V

    Absolute maximum

  • Grid #1 Positive Voltage

    - to 0 V

    Absolute maximum

  • Peak Voltage Between Anode #2 and Deflecting Electrode DJ1 or DJ4

    - to 385 V

  • Anode #2 and Grid #2 Voltage - Operating Point 1

    400 V

  • Anode #2 and Grid #2 Voltage - Operating Point 2

    600 V

  • Anode #1 Voltage for Focus - Operating Point 1

    100 V

    75% of grid #1 cutoff voltage

  • Anode #1 Voltage for Focus - Operating Point 2

    150 V

    75% of grid #1 cutoff voltage

  • Grid #1 Voltage for Visual Cutoff - Operating Point 1

    -40 V

  • Grid #1 Voltage for Visual Cutoff - Operating Point 2

    -60 V

  • Grid #1 Circuit Resistance

    - to 1.5 MΩ

    Maximum circuit value

  • Deflecting Electrode Circuit Impedance at Heater Supply Frequency

    - to 1 MΩ

    Maximum circuit value

  • Resistance in Any Deflecting Electrode Circuit

    - to 5 MΩ

    Maximum circuit value