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16MP4

Direct-view cathode-ray picture tube documented by manufacturer data for type 16MP4; available extracted technical detail is limited, so the description remains conservative.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized

Sections: 1
Base: 12N
Socket code: DUODECAL5
Base pins: 5
Nominal heater: 6.3 V / 600 mA

Description

16MP4 — Cathode Ray Picture Tube

A direct-view, round glass cathode ray tube designed for television applications, featuring magnetic focus and deflection, an external double field ion trap, and an external conductive coating.

Overview

The 16MP4 and 16MP4A are direct-view cathode ray picture tubes designed specifically for television receiver applications. These two types are electrically and mechanically identical with a single physical distinction: the 16MP4A incorporates a grey filter faceplate to improve picture contrast under ambient light, whereas the standard 16MP4 uses a clear faceplate.

Both tubes feature a round glass construction, a unipotential cathode, magnetic focusing, and magnetic deflection. They are designed to operate with an external double field ion trap magnet and utilize an external conductive bulb coating. The design is optimized to display a standard 10 1/2" by 14 3/4" raster size.

Mechanical Design and Physical Dimensions

The 16MP4 is constructed with a round glass envelope. The physical dimensions and alignment tolerances are critical for proper mounting, deflection yoke placement, and focus coil positioning within a television chassis.

Envelope and Screen Dimensions

Overall Length: 21 3/4 ± 3/8 inches
Greatest Diameter of Bulb: 16 1/8 ± 1/8 inches
Minimum Useful Screen Diameter: 14 3/4 inches
Neck Diameter: 1 7/16 ± 1/16 inches
Deflection Angle (Approximate): 60 degrees

Component Positioning and Clearances

The neck of the tube requires specific clearances for external magnetic components:

Ion Trap Magnet Space: A length of 4 5/8 ± 3/16 inches along the neck, measured from the base, must be kept clear for the installation and adjustment of the external double field ion trap magnet.
Anode Terminal Distance: The anode terminal is located on the cone of the bulb, positioned at a distance of 5 5/16 + 3/8 - 1/8 inches from the reference line.
Reference Line to Faceplate: The distance from the reference line to the front edge of the bulb is 13 1/4 + 3/16 - 1/16 inches.

Base and Bulb Contacts

Bulb Contact: Recessed small cavity cap (J1-21 designation).
Base: Small shell duodecal 5-pin base (B5-57 designation).
Basing Configuration: 12N.
Bulb Contact Alignment: The J1-21 anode contact aligns with pin position #3 within a tolerance of ± 10 degrees.

Electrical Connections and Basing

The 16MP4 uses a duodecal base with five active pins, plus an anode cap on the side of the glass cone. The pin connections, viewed from the bottom of the base, are assigned as follows:

Pin / Terminal	Connection
Pin 1	Heater
Pin 2	Grid No. 1
Pin 10	Grid No. 2
Pin 11	Cathode
Pin 12	Heater
Anode Cap	Anode

Heater Characteristics

The unipotential cathode is indirectly heated. The heater is designed for parallel AC or DC operation.

Heater Parameter	Value
Nominal Heater Voltage	6.3 V
Nominal Heater Current	0.6 A
Calculated Heater Power	3.78 W

The calculated heater power is derived directly from the nominal ratings (6.3 V * 0.6 A = 3.78 W).

Electrical Characteristics and Typical Operating Points

The 16MP4 operates with high anode voltages and utilizes magnetic fields for both electron beam focusing and deflection.

Interelectrode Capacitances

The external conductive coating on the glass envelope forms a capacitor with the internal anode coating. This capacitance can be utilized as a filter capacitor for the high-voltage anode power supply.

Maximum External Coating to Anode Capacitance: 3,500 pF (µµf)
Minimum External Coating to Anode Capacitance: 1,500 pF (µµf)

Typical Operating Conditions

The typical operating parameters represent a standard configuration for television service:

DC Anode Voltage: 12,000 Volts
DC Grid No. 2 Voltage: 300 Volts
DC Grid No. 1 Voltage: -33 to -77 Volts (configured for visual extinction of the undeflected focused spot)
DC Focusing Coil Current (Approximate): 110 mA
DC Ion Trap Current (Approximate): 120 mA

Focusing and Ion Trap Specifications

The typical focusing coil current of 110 mA is specified for a standard focus coil #109 (or equivalent) under the following conditions:

The combined Grid No. 1 bias voltage and video signal voltage are adjusted to produce a highlight brightness of 20 foot-lamberts on the standard 10 1/2" by 14 3/4" picture.
The distance from the reference line to the center of the air gap on the focus coil must be maintained at 3.25 inches.

The typical ion trap current of 120 mA is specified when using a standard ion trap coil #108.

Maximum Ratings and Circuit Limits

The ratings below are established under the Design Center system. Operating the tube beyond these limits may impair its performance and shorten its service life.

Electrode Voltage Limits

Maximum DC Anode Voltage: 14,000 Volts
Maximum DC Grid No. 2 Voltage: 410 Volts
Maximum Grid No. 1 Voltage:
- DC Negative-Bias Value: 125 Volts
- DC Positive-Bias Value: 0 Volts
- Positive-Peak Value: 2 Volts

Heater-Cathode Voltage Limits

To prevent insulation breakdown between the heater and the cathode, the potential difference between these elements must be kept within the following limits:

Heater Negative with Respect to Cathode:
- During Warm-up Period (not to exceed 15 seconds): 410 Volts maximum
- After Equipment Warm-up Period: 125 Volts maximum
Heater Positive with Respect to Cathode: 125 Volts maximum

Circuit Resistance Limits

Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms

Optical and Screen Characteristics

The screen of the 16MP4 utilizes a specialized phosphor blend to provide a clear monochrome image.

Phosphor Number: No. 4
Fluorescent Color: White
Phosphorescent Color: White
Persistence: Medium

The screen is capable of displaying a standard 10 1/2" by 14 3/4" raster. The 16MP4A variant incorporates a grey-tinted faceplate, which reduces reflections and enhances the contrast ratio when the television receiver is operated in brightly lit environments.

Technical Summary

The 16MP4 and 16MP4A are 60-degree, magnetic-focus, magnetic-deflection cathode ray picture tubes designed for monochrome television receivers. Operating with a nominal 6.3 V, 0.6 A heater, these tubes feature a 16 1/8-inch round glass envelope, a small shell duodecal 5-pin base (B5-57), and a recessed small cavity anode cap (J1-21).

The electrical design supports a maximum design-center anode voltage of 14,000 V and typical operation at 12,000 V, producing a 10 1/2" by 14 3/4" raster. Beam focusing is achieved magnetically, typically requiring 110 mA through a standard focus coil, while ion separation is managed via an external double field ion trap magnet requiring approximately 120 mA. The 16MP4A is distinguished solely by its grey filter faceplate, which provides superior contrast compared to the clear faceplate of the standard 16MP4.

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: 12N
Socket code: DUODECAL5
Base pins: 5
Nominal heater voltage: 6.3 V
Nominal heater current: 600 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

12N - 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: 14000 V
Max screen voltage: 41 V

CRT-specific anode/focus/deflection ratings retained as parameters rather than mapped to ordinary plate/screen fields.

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

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

Maximum Anode Voltage
14000 V
Typical Anode Voltage
12000 V
Maximum Grid2 Voltage
410 V
Typical Grid2 Voltage
300 V

Characteristic

DeflectionAngleApproximate
70 degree
FocusingMethod
Magnetic
DeflectingMethod
Magnetic
PhosphorNumber
4
FluorescentColor
White
Persistence
Medium

Data set 02

1966 Tung Sol Electronic Tubes 4 of 4

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

MAGNETIC FOCUS 8 DEFLECT90N
8 mA
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
EXTERNAL DOUBLE FIELD ION TRAP — value 1
1
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
EXTERNAL DOUBLE FIELD ION TRAP — value 2
2
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
EXTERNAL DOUBLE FIELD ION TRAP — value 3
3
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
DEFLECTION ANGLE (APPROX.)
6 degrees
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
HEATER VOLTAGE
6.3 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
SFOP STANO ARD FOCUS COIL W109, OR EQUIVALENT, WITX THE COMBINED GRID 41 BIAS VOLTAGE AMD VIDEO
41 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
SIGNAL VOLTAGE ADJUSTED TO PRODUCE A XIGMLI GHT BRIGX ?NESS OF 20 F00T LAMBERTS OX A 10 1/2" BY — value 1
10 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
SIGNAL VOLTAGE ADJUSTED TO PRODUCE A XIGMLI GHT BRIGX ?NESS OF 20 F00T LAMBERTS OX A 10 1/2" BY — value 2
1 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
SIGNAL VOLTAGE ADJUSTED TO PRODUCE A XIGMLI GHT BRIGX ?NESS OF 20 F00T LAMBERTS OX A 10 1/2" BY — value 3
2 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
14 j/N" PICTURE SIZE. DISTANCE FROM REFERENCE LIME TO CENTER OF AIR GAP ON FOCUS COIL SMALL BE
14 mA
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.

Other

MAXIMUM DC ANODE VOLTAGE
14000 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
MAXIMUM DC GRID #2 VOLTAGE — value 1
2 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
MAXIMUM DC GRID #2 VOLTAGE — value 2
41 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
MAXIMUM GRID #1 VOLTAGE
1 V
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
MAXIMUM GRID #1 CIRCUIT RESISTANCE — value 1
1 mA
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.
MAXIMUM GRID #1 CIRCUIT RESISTANCE — value 2
1.5 mA
Published CRT datasheet value; multiple values on a row represent the source table's separate conditions/limits.