Specialized - Cathode Ray ·CathodeRay
Cathode-ray display tube documented by manufacturer data for type 12CP4; available extracted source information is sparse, so no more specialized application or construction claim is made.
The 12CP4 is a short twelve-inch cathode-ray tube, historically designated as a "Videotron," designed for television and display applications. It features an indirectly heated cathode and utilizes electromagnetic methods for both electron beam deflection and focusing. The tube is characterized by its ability to produce a white fluorescent screen color.
The 12CP4 operates with an indirectly heated cathode requiring a low-voltage, high-current heater supply. The electrical ratings and maximum limits for the electrodes are defined as follows:
| Parameter | Value / Limit |
|---|---|
| Heater Voltage | 2.5 V |
| Heater Current | 2.1 A |
| Maximum High-Voltage Anode | 7000 V |
| Control Grid Voltage | Never positive |
| Maximum Fluorescent Screen Input Power | 10 mW/cm² |
The control grid must be operated such that its potential never becomes positive relative to the cathode. Additionally, the power input to the fluorescent screen must be restricted to a maximum of 10 milliwatts per square centimeter to prevent damage to the phosphor.
The 12CP4 can be operated under different anode voltage conditions. The typical operating parameters for two distinct anode voltage levels are outlined below:
| Parameter | Operating Point 1 | Operating Point 2 | Unit |
|---|---|---|---|
| Anode Voltage | 6000 | 7000 | Volts |
| Control Grid Voltage | Adjust for suitable luminous spot | Adjust for suitable luminous spot | — |
| Control Grid Voltage for Cut-off | -90 | -110 | Volts |
| Control Grid Peak-to-Peak Voltage | 25 | 25 | Volts |
At either operating point, the control grid voltage is adjusted to achieve a suitable luminous spot on the screen. The grid bias required to completely cut off the electron beam is -90 volts when the anode is at 6000 volts, and increases to -110 volts when the anode is operated at its maximum rating of 7000 volts. Under both conditions, the typical peak-to-peak control grid voltage is 25 volts.
The direct interelectrode capacitance between the control grid and the cathode is approximately 12 µµF.
The 12CP4 is constructed with a short-neck bulb design to minimize the overall depth of the display equipment. Its physical dimensions are specified as follows:
The tube utilizes a specialized base designated as 4AF-0-0. The pin connections, viewed from the bottom of the tube base, are assigned as follows:
General specifications
Properties common to every published source and operating point.
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
1 physical section, each with unique specifications.
Section 1
Promoted ratings/characteristics read from the approved National Union datasheet.
Source-dependent data
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.
Data set 01
Published operating points and test conditions from this source.
Control grid cutoff voltage
- to -110 V
At 6000-7000 V anode
Fluorescent screen input power
10 mW/cm^2
White fluorescent screen