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16ADP7

Sixteen-inch metal-shell P7 oscillograph tube with magnetic focusing and approximately 53-degree deflection, intended for low-frequency waveform display and typically operated around a 12 kV ultor supply.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized

Sections: 1
Base: -
Socket code: B12C
Base pins: -
Nominal heater: -

Description

16ADP7 — Metal-Shell 16-Inch Oscillograph Tube

The 16ADP7 is a 16-inch metal-shell cathode-ray oscillograph tube designed for applications requiring a temporary record of electrical phenomena. It utilizes magnetic focus and magnetic deflection with a nominal 53-degree deflection angle. The tube is particularly suited for radar indicator service and general oscillographic applications where grid No. 1 is pulse-modulated at low frequencies.

Optical and Screen Characteristics

The 16ADP7 features a cascade (two-layer) screen designated with P7 phosphor. This screen exhibits a dual-persistence characteristic:

Fluorescence: A short-persistence bluish light emitted during excitation.
Phosphorescence: A long-persistence greenish-yellow light that remains visible for several minutes under conditions of adequate excitation and low ambient light.

This long-persistence characteristic makes the tube highly effective for observing low-speed non-recurring phenomena or high-speed recurring phenomena. It also permits the simultaneous observation of multiple phenomena using an external switching arrangement.

Without an optical filter, the 16ADP7 can operate at scanning frequencies as low as 30 cycles per second without causing excessive flicker. For operation at even lower scanning frequencies, a yellow filter such as a Wratten No. 15 (G) can be placed over the tube face to reduce the visual effect of the initial short-persistence blue fluorescence, emphasizing the long-persistence phosphorescence. Conversely, if only the short-persistence fluorescence is desired, a blue filter such as a Wratten No. 47A can be used to filter out the greenish-yellow phosphorescence. While the tube can function as a short-persistence device, its inherent persistence is slightly longer than that of a standard P11 phosphor, meaning photographic recording in this mode should be limited to moderate film speeds.

The faceplate is constructed of Filterglass, which provides approximately 66% light transmission. The Filterglass incorporates a neutral light-absorbing material that reduces ambient-light reflections from the phosphor and internal reflections within the faceplate itself at a much higher ratio than it reduces the directly viewed light of the trace. This significantly improves trace contrast. The relatively flat surface of the faceplate also facilitates the use of an external, transparent, calibrated scale.

Electron Gun and Focusing Systems

The electron gun of the 16ADP7 incorporates a limiting aperture at its end. This design feature produces a sharper, rounder spot on the screen, resulting in greater effective resolution. This is particularly beneficial in pulse-modulated applications where high grid No. 1 drive leads to high beam currents.

Focusing and deflection are both achieved magnetically:

Deflection Angle: Approximately 53 degrees.
Focusing Coil Current: Under typical operating conditions with an ultor voltage of 12,000 V and an ultor current of 200 microamperes, a specimen focusing coil (similar to JETEC No. 109) requires a direct current of 95 ± 15% mA. This specification assumes the focusing coil is positioned with its air gap toward the faceplate and the center line of the air gap located 3-1/4 inches from the reference line.
Spot Position: The center of the undeflected, unfocused spot falls within a circle of 25-mm radius concentric with the center of the tube face.

Electrical Characteristics and Operating Points

The 16ADP7 is equipped with an indirectly heated, coated unipotential cathode. The electrical and interelectrode capacitance characteristics are detailed below:

Heater and Capacitance Data

Heater Voltage (AC or DC): 6.3 V
Heater Current: 0.6 A
Grid No. 1 to All Other Electrodes Capacitance: 6 µµF (approximate)
Cathode to All Other Electrodes Capacitance: 5 µµF (approximate)

Maximum Ratings (Design-Center Values)

Ultor Voltage: 14,000 max volts (Grid No. 3, which has the ultor function, and the collector are connected together internally and referred to collectively as the "ultor").
Grid-No. 2 Voltage (Positive): 410 max volts (DC or Peak AC)
Grid-No. 2 Voltage (Negative): 180 max volts (DC or Peak AC)
Grid-No. 1 Voltage (Negative Bias): 180 max volts
Grid-No. 1 Voltage (Positive Bias): 0 max volts
Grid-No. 1 Voltage (Positive Peak): 2 max volts
Peak Grid-No. 1 Drive from Cutoff: 65 max volts
Peak Heater-Cathode Voltage (Heater negative or positive with respect to cathode): 125 max volts
Ultor Input Power: The effective resistance of the ultor supply must be adequate to limit the ultor input power to 6 watts.

Typical Operation

Ultor Voltage: 12,000 V (Operation below 8,000 V is not recommended, as brilliance and definition decrease significantly with lower voltages).
Grid-No. 2 Voltage: 250 V
Grid-No. 1 Voltage (for visual extinction of undeflected focused spot): -27 to -63 V
Grid-No. 2 Current: -15 to +15 µA
Grid-No. 1 Circuit Resistance: 1.5 max megohms

Physical Construction, Basing, and Installation

The 16ADP7 features a robust metal-shell envelope with a glass faceplate. Its physical dimensions and basing configuration are as follows:

Maximum Overall Length: 22 inches
Greatest Diameter at Lip: 15-7/8 inches ± 1/8 inch
Minimum Useful Screen Diameter: 14-3/8 inches
Base: Small-Shell Duodecal 7-Pin (JETEC No. B7-51)
Mounting Position: Any

Pin Connections (Bottom View)

Pin 1: Heater
Pin 2: Grid No. 1
Pin 6: No Connection
Pin 7: No Connection
Pin 10: Grid No. 2
Pin 11: Cathode
Pin 12: Heater
Cap (Metal-Shell Lip): Grid No. 3, Collector (Ultor Terminal)

Installation and Safety Precautions

Because the metal shell and glass face operate at high voltage, any material in contact with either the shell or the face must be thoroughly insulated to withstand the maximum applied ultor voltage. Additionally, the socket for the duodecal base must not be rigidly mounted; it should utilize flexible leads and be allowed to move freely to prevent mechanical stress on the tube.

Grid-Drive Characteristics

The average grid-drive characteristics of the 16ADP7 illustrate the relationship between the ultor current (in microamperes) and the video signal voltage (in volts from cutoff) under different Grid-No. 2 operating potentials:

At a Grid-No. 2 voltage of 250 V, the ultor current rises from 0 µA at cutoff to approximately 200 µA with a video signal drive of 30 V, and reaches approximately 450 µA at 45 V of drive.
At a Grid-No. 2 voltage of 400 V, the drive characteristic is shifted, requiring a higher video signal voltage for equivalent beam currents. For example, a drive of 30 V yields approximately 150 µA, while a drive of 50 V is required to reach approximately 500 µA.

These curves demonstrate how the limiting aperture maintains spot quality even as the grid drive and resulting beam current are increased.

Technical Summary

The 16ADP7 is a 16-inch, metal-shell, magnetically focused and deflected oscillograph tube featuring a long-persistence P7 cascade screen and a high-contrast Filterglass faceplate. Operating with a 6.3 V, 0.6 A heater, it is designed for high-resolution display of electrical phenomena, particularly in radar indicator and low-frequency pulse-modulated applications. With an ultor rating of up to 14,000 V and a specialized limiting aperture in its electron gun, the 16ADP7 provides a sharp, high-contrast trace capable of being viewed directly, filtered for specific persistence characteristics, or recorded photographically.

Socket description

Duodecar 12-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: B12C
Base pins: -
Nominal heater voltage: -
Nominal heater current: -
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.

Source-derived section; promoted fields populated where applicable.

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

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

53° peflection Angle Filterglass Face 22" Max. Length
22
53° peflection Angle Filterglass Face 22" Max. Length
RCA-[
6
RCA-[6ADP7 is a |6-inch oscillograph tube of the metal-shell type utiliz-
as
30
as 30 cycles
Voltage (AC or DC)
6.3 V
Voltage (AC or DC) 6.3 volts
Current. . . . . e e e e s
600 mA
Current. . . . . e e e e s . 0.6 ampere
Cathode to Al{ Other Electrodes
5 pF
Cathode to Al{ Other Electrodes. . . . . . . . 5 uuf
ULTOR® VOLTAGE « + « v v v v v v v v v v v a v o
14000 V
ULTOR® VOLTAGE « + « v v v v v v v v v v v a v o 14000 max. volts
GRID-No
2
GRID-No.2 VOLTAGE:
Positive value (DC or Peak AC)
410 V
Positive value (DC or Peak AC) . . . . . . . . . 410 max, volts
Negative value (DC or Peak AC) . . « . . + « « . |
80 V
Negative value (DC or Peak AC) . . « . . + « « . |80 max. volts
Negative bias value. . . . . . . « « « + « «
180 V
Negative bias value. . . . . . . « « « + « « . . 180 max. volts
Positive bias value® . . . . . . . . « . . .«
0 V
Positive bias value® . . . . . . . . « . . .« . 0 max. volts
Positive peak value. . . e e e e e e e
2 V
Positive peak value. . . e e e e e e e 2 max, volts
PEAK GRID—No. | DRIVE FROM CUTOFF e e e e e e e
65 V
PEAK GRID—No. | DRIVE FROM CUTOFF e e e e e e e 65 max. volts
Heater negative with respect to cathode. . . . . {
25 V
Heater negative with respect to cathode. . . . . {25 max. volts
Heater positive with respect to cathode
125 V
Heater positive with respect to cathode. . . . . 125 max. volts
Ultor Voltage® . . . . ¢ ¢ v v & v v v & o o« o o
12000 V
Ultor Voltage® . . . . ¢ ¢ v v & v v v & o o« o o 12000 volts
Grid-No
250 V
Grid-No.2 Voltage. . . . . e e e e e e e e e e 250 volts
of Undeflected Focused Spot
-63 V
of Undeflected Focused Spot. . . . . -27 to -63 volts
Grid-No
15
Grid-No.2 Current. . . e e e e e e e e e e -15 to +15 pamp
Focusing—Coil Current (DC)Oo e e e e e e e e
5 mA
Focusing—Coil Current (DC)Oo e e e e e e e e 95 t 5% ma
Grid—-No. |~Circuit Resistance . . . . . . . . . . . |
5
Grid—-No. |~Circuit Resistance . . . . . . . . . . . |.5 max. megohms
in the
3
in the 16ADP7, grid No.3 which has the ultor the ultor voltage should not be less than
function, and collector are connected together
8000 V
function, and collector are connected together 8000 volts,
which is applied the highest dc voltage for and ultor current of
200
which is applied the highest dc voltage for and ultor current of 200 microamperes. The
Brilliance and definition decrease with will fall within a circle having
25 mm
Brilliance and definition decrease with will fall within a circle having 25-mm radius
FHE ¢ =
6.3 V
FHE ¢ = 6.3 VOLTS
b COLLECTOR) VOLTS =
14000 V
b COLLECTOR) VOLTS = 8000 TO 14000
92CM - 7692
7692
92CM - 7692
92CM - 7690
7690
92CM - 7690
NOTE
3
NOTE 3: METAL SHELL AND GLASS FACE OPERATE ATHIGH VOLTAGE. ANY MATERIAL