Specialized - Cathode Ray ·CathodeRay
Sixteen-inch P4 direct-view picture tube rated for approximately 12–17.6 kV anode operation, with about 15 kV typical. RMA/EIA documentation supports its use as a high-voltage monochrome television display.
The 16BXP4 is a 16-inch direct-view rectangular glass-envelope cathode-ray tube (CRT) designed for television receiver applications. It features a wide 114-degree magnetic deflection angle, electrostatic focusing, and a specialized cathode-drive design. The tube incorporates a P4 aluminized phosphor screen, a gray filter glass faceplate, and a filled rim implosion protection system with integrated mounting holes. It is designed to operate with a low Grid No. 2 voltage of 35 V and does not require an ion trap.
The 16BXP4 is constructed with a rectangular glass envelope (bulb designation J125B1A) and a protective metal rim that provides implosion protection and mounting holes. The physical dimensions of the tube are highly compact, featuring a short neck length of 4 3/8 ± 1/8 inches and an overall length of 10 9/16 ± 1/4 inches.
The greatest dimensions of the tube, including the metal rim, are:
The minimum useful screen dimensions (projected) are:
The tube has an approximate weight of 9 pounds 14 ounces. It uses a J1-21 high-voltage bulb contact for the anode connection, which is aligned with pin position No. 7 within a tolerance of ±30 degrees. The base is a B6-214 type, utilizing the 7FA basing configuration.
The 16BXP4 is equipped with an indirectly heated cathode. The heater is designed to operate at a nominal voltage of 6.3 V with a current draw of 450 mA ± 5%. The heater has a controlled warm-up time of 11 seconds.
Using the nominal heater voltage (6.3 V) and the nominal heater current (0.45 A), the calculated heater power consumption is:
6.3 V * 0.45 A = 2.835 W
The 16BXP4 uses the 7FA basing arrangement. The pin connections, viewed from the bottom of the base, are as follows:
| Pin | Connection |
|---|---|
| 1 | Heater |
| 2 | Cathode |
| 3 | No Connection |
| 4 | Heater |
| 5 | Grid No. 1 |
| 6 | Grid No. 4 (Focusing Electrode) |
| 7 | Grid No. 2 |
| Recessed Contact | Anode (J1-21 bulb contact) |
The reference line of the tube is determined by Plane C-C' of J.E.D.E.C. using Reference Line Gauge No. 126.
The ratings of the 16BXP4 are defined under the Design Maximum System. Unless otherwise specified, all voltage values are positive and measured with respect to Grid No. 1.
In typical cathode drive service, all voltages are positive with respect to Grid No. 1:
The 16BXP4 features a P4 aluminized phosphor screen, which provides a white display suitable for television applications. The faceplate is made of gray filter glass with an approximate light transmittance of 55% at the center, enhancing contrast under ambient light conditions.
A key performance parameter is the Anode Penetration Current (or maximum beam current), which is rated at a maximum of 150 uA. This limit is defined under specific test conditions: 17,600 Volts (design maximum) applied to the anode, zero voltage applied to the cathode, Grid No. 1, and Grid No. 2, with all other elements operating at their nominal voltages.
During typical operation, focusing is evaluated with the combined Grid No. 1 bias voltage and video-signal voltage adjusted to produce an anode current of 125 microamperes on a 12 15/16 by 10 1/4 inches pattern (using an RCA 2F21 Monoscope or equivalent).
The 16BXP4 is a 16-inch rectangular glass-envelope cathode-ray tube featuring a 114-degree magnetic deflection angle, electrostatic focusing, and a low Grid No. 2 operating voltage of 35 V. It is designed for cathode-drive television receiver applications, utilizing a P4 aluminized screen and gray filter glass with 55% light transmittance. The tube incorporates a filled rim implosion protection system with integrated mounting holes, reducing the overall depth of the receiver cabinet with its short 10 9/16-inch length. Operating under the Design Maximum System, it supports anode voltages up to 17,600 V and utilizes a standard 7FA basing configuration with a 6.3 V, 450 mA heater.
Duodecar 12-contact
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
CRT anode/ultor voltage is represented in MaxPlateVoltage; additional electrode, drive, optical, and capacitance data retained as parameters.
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.
Minimum anode voltage
12000 V
Maximum anode voltage
17600 V
Minimum anode voltage
12000 V
Typical anode voltage
15000 V
Maximum grid No. 2 voltage
60 V
Minimum grid No. 2 voltage
25 V
Typical grid No. 2 voltage
35 V
Maximum heater voltage
7 V
Minimum heater voltage
5.8 V
Grid No. 1 to other electrodes capacitance
6 pF
External conductive coating capacitance
1400 pF