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19GEP4

Wide-angle aluminized P4 monochrome television picture tube using electrostatic focusing and magnetic deflection, designed for high-voltage direct-view service with a large approximately 19-inch screen.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized

Sections: 1
Base: -
Socket code: DUODECAL5
Base pins: -
Nominal heater: 6.3 V / 450 mA

Description

19GEP4 — Black and White Television Picture Tube

The 19GEP4 is a 19-inch cathode-ray tube designed for black and white television receivers. It features low-voltage electrostatic focusing, magnetic deflection, and an aluminized P4 phosphor screen. The tube incorporates a tension-band implosion protection system with integrated mounting lugs.

Mechanical Design and Implosion Protection

The 19GEP4 is built using the EIA J149-F1A glass bulb envelope and features a net weight of approximately 15 lbs. The physical dimensions of the tube are characterized by:

Overall Length: 11.625" ± 0.250"
Neck Length: 4.375" ± 0.125"
Maximum Neck Diameter: 1.168" at the splice
Greatest Dimensions (excluding mounting lugs):
- Diagonal: 18.733" ± 0.125"
- Width: 16.552" ± 0.125"
- Height: 13.446" ± 0.125"

The screen utilizes an aluminized P4 phosphor with a light transmittance of approximately 49% at the center. The projected minimum useful screen dimensions are:

Diagonal: 17.562"
Horizontal: 15.188"
Vertical: 12.000"
Minimum Useful Area: 172 sq. in.

For safety, the tube is equipped with a banded implosion protection system (Tension Band) with mounting lugs. This hardware must be grounded. The minimum resistance between the external conductive coating and the implosion hardware is 5 MΩ.

Heater and Electrical Connections

The 19GEP4 is equipped with an indirectly heated cathode designed for series or parallel heater chains. The heater has a nominal warm-up time of 11 seconds.

Heater Parameter	Value
Nominal Heater Voltage	6.3 V
Nominal Heater Current	450 ± 5% mA
Calculated Heater Power	2.835 W

Note: The heater power is calculated as 6.3 V multiplied by 0.45 A.

The tube uses an EIA B7-208 base with an EIA 8HR basing configuration. The high-voltage anode connection is made via a recessed EIA J1-21 bulb contact on the side of the envelope.

Pinout Configuration (EIA 8HR)

The electrical connections are assigned as follows:

Pin Number	Electrode Connection
Pin 1	Heater
Pin 2	Grid No. 1
Pin 3	Grid No. 2
Pin 4	Grid No. 4 (Focusing Electrode)
Pin 6	Grid No. 1
Pin 7	Cathode
Pin 8	Heater
Recess	Anode (EIA J1-21 Bulb Contact)

Electrostatic Focusing and Magnetic Deflection

The 19GEP4 utilizes low-voltage electrostatic focusing, controlled by Grid No. 4. Deflection is achieved magnetically, requiring an external deflection yoke. The deflection angles are:

Diagonal Deflection: 114°
Horizontal Deflection: 102°
Vertical Deflection: 86°

For beam centering, a permanent magnet (PM) centering magnet capable of producing 0 to 8 gauss may be used. This magnet should extend no more than 2.125" from the Yoke Reference Line (EIA No. 126).

Electrical Characteristics and Capacitances

The direct interelectrode capacitances of the tube are:

Cathode to all other electrodes: approximately 5 pF
Grid No. 1 to all other electrodes: approximately 6 pF
External conductive coating to anode (including implosion hardware): Minimum 1250 pF, Maximum 1750 pF

The capacitance between the external coating and the internal anode acts as a high-voltage filter capacitor when the coating is properly grounded.

Operating Ratings and Typical Cathode Drive Operation

All voltages are specified relative to Grid No. 1.

Absolute Maximum and Minimum Ratings

Parameter	Minimum Value	Maximum Value
Anode Voltage	11,000 V	23,000 V
Grid No. 4 (Focusing) Voltage	−550 V	+1100 V
Grid No. 2 Voltage	200 V	550 V
Cathode Bias Voltage (Negative)	—	0 V
Cathode Peak Voltage (Negative)	—	2 V
Cathode Bias Voltage (Positive)	—	154 V
Cathode Peak Voltage (Positive)	—	220 V

Heater-Cathode Voltage Limits

The maximum allowable voltage differences between the heater and the cathode depend on polarity and timing:

Heater negative to cathode (during warm-up, ≤ 15 seconds): 450 V maximum
Heater negative to cathode (after warm-up): 300 V maximum
Heater positive to cathode: 200 V maximum

Limiting Circuit Values

Maximum Grid No. 1 Circuit Resistance: 1.5 MΩ
Minimum Grid No. 2 & Grid No. 4 Circuit Resistance: 10,000 Ω

The inclusion of protective resistance in the Grid No. 2 and Grid No. 4 circuits is advised to safeguard the tube against damage from momentary internal arcs.

Typical Cathode Drive Operating Conditions

Under typical operating conditions, the tube is configured with the following parameters:

Anode Voltage: 18,000 V
Grid No. 4 Voltage: 0 to 400 V
Grid No. 2 Voltage: 400 V
Cathode Voltage for Raster Cut-off: 36 to 78 V

Radiation Safety Note

When operating the 19GEP4, shielding may be required to protect against soft X-rays if the anode voltage is allowed to exceed 16 kV.

Technical Summary

The 19GEP4 is a 114° magnetic deflection, low-voltage electrostatic focus black and white television picture tube. It features a 19-inch diagonal screen with an aluminized P4 phosphor and a tension-band implosion protection system that requires grounding. Operating with a 6.3 V, 450 mA heater, the tube is typically driven via the cathode with an anode voltage of 18,000 V, requiring a raster cut-off voltage between 36 and 78 V.

Socket description

Small-shell Duodecal 5-contact CRT base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: DUODECAL5
Base pins: -
Nominal heater voltage: 6.3 V
Nominal heater current: 450 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

No fixed ratings are recorded for this section.

Television CRT electron-gun/display section.

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

1965 Westinghouse Data Book

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

Heater Voltage
6.3 V
Heater Current
450 mA
Heater Warm-up Time
11 s
Focusing Method
Low Voltage Electrostatic text
Deflection Method
Magnetic text
Horizontal Deflection Angle
102 deg
Approximate
Vertical Deflection Angle
86 deg
Approximate
Diagonal Deflection Angle
114 deg
Approximate
Phosphor
Aluminized P4 text
Fluorescence
White text
Persistence
Short to Medium text
Light Transmittance
49 percent
Approximate
Cathode-to-All Capacitance
5 pF
Approximate
Grid1-to-All Capacitance
6 pF
Approximate
External Coating-to-Anode Capacitance Minimum
1250 pF
External Coating-to-Anode Capacitance Maximum
1750 pF

Other

Maximum Anode Voltage
23000 V
Minimum Anode Voltage
11000 V
Maximum Focus Electrode Voltage Positive
1100 V
Grid4
Maximum Focus Electrode Voltage Negative
-550 V
Grid4
Maximum Grid2 Voltage
550 V
Minimum Grid2 Voltage
200 V
Maximum Heater-Cathode Voltage During Warmup
450 V
Duration<=15s
Maximum Heater-Cathode Voltage After Warmup
300 V
Typical Anode Voltage
18000 V
CathodeDrive
Typical Focus Voltage Minimum
0 V
Grid4
Typical Focus Voltage Maximum
400 V
Grid4
Typical Grid2 Voltage
400 V
CathodeDrive
Cathode Voltage for Raster Cutoff Minimum
36 V
CathodeDrive
Cathode Voltage for Raster Cutoff Maximum
78 V
CathodeDrive
Maximum Grid1 Circuit Resistance
1.5 Mohm