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

925QM

Nine-inch high-resolution display CRT with magnetic focusing and deflection and an optically flat metal-backed screen. Its high-voltage construction is intended for precision image presentation and recording.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
B12A
Socket code
-
Base pins
-
Nominal heater
6.3 V / 300 mA

Description

Nine-inch high-resolution display CRT with optically flat metal-backed screen and magnetic focus and deflection.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
B12A
Socket code
-
Base pins
-
Nominal heater voltage
6.3 V
Nominal heater current
300 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

B12A - 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
30000 V

Promoted fields were populated only where the Ferranti sheet maps cleanly to the locked schema; additional ratings and operating values are retained in TUBE_SECTION_PARAMETER.

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

1963 Ferranti

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Anode voltage

    20000 V

  • Visual cutoff grid voltage

    -90 V

  • X-ray shielding threshold

    16000 V

    ShieldingMayBeRequiredAbove

Capacitance

  • Cathode-to-all capacitance maximum

    8 pF

  • Grid-to-all capacitance maximum

    8 pF