12ANP14 — Electrostatic Deflection and Focus Cathode-Ray Tube

The 12ANP14 is a 12-inch direct-viewed, round glass cathode-ray tube designed primarily for oscilloscope applications. It features electrostatic deflection, electrostatic focusing, post-deflection acceleration, and an aluminized screen. The tube incorporates a gray filter glass faceplate to enhance display contrast.

Optical and Phosphor Characteristics

The 12ANP14 is distinguished by its use of the P14 phosphor screen. This phosphor is characterized by:

• Fluorescence: Purple
• Phosphorescence: Orange
• Persistence: Medium-Long

Other variants in the 12ANP family utilize different phosphors, such as P7 (blue-white fluorescence, yellow phosphorescence, long persistence), P19 (orange fluorescence and phosphorescence, long persistence), and P25 (orange fluorescence and phosphorescence, long persistence). The 12ANP14's specific combination of purple fluorescence and orange medium-long phosphorescence makes it suitable for applications requiring visual tracking of transient waveforms.

The tube features a minimum useful screen diameter of 11 inches, providing a large viewing area for detailed waveform analysis.

Mechanical Design, Base, and Pinout

The 12ANP14 is constructed with a round glass bulb and utilizes a Medium Shell Diheptal 12-Pin base (B12-37) with a 14AW basing arrangement.

Physical Dimensions

• Overall Length: 22 1/2  3/8 inches
• Maximum Bulb Diameter: 12 7/16 (+1/16, -3/32) inches
• Neck Diameter: 2 inches nominal
• Faceplate Radius of Curvature: 40 inches
• Funnel Radius: 24 inches

Electrical Connections and Alignment

The tube features specialized external contacts to facilitate high-voltage and deflection connections:

• Bulb Contact: Recessed Small Cavity Cap (J1-22)
• Neck Contacts: Small Ball Caps (J1-25)

Precise mechanical alignment is specified for installation:

• The J1-22 bulb contact aligns with the D3-D4 trace within 10 degrees.
• The J1-22 bulb contact aligns with Pin No. 11 within 10 degrees.
• The neck contact (A2) aligns with the D1-D2 trace within 10 degrees.
• The angle between the D1-D2 trace and the D3-D4 trace is 90  1 degree.

Deflection direction is defined relative to these elements:

• A positive voltage on deflecting plate D1 deflects the electron beam approximately away from the A2 neck contact.
• A positive voltage on deflecting plate D3 deflects the electron beam approximately away from the post-accelerator button.

Electrical Ratings and Operating Conditions

The 12ANP14 operates with an indirectly heated cathode. The heater requirements and absolute maximum ratings must be strictly observed to ensure reliable operation.

Heater Data

• Heater Voltage: 6.3 Volts
• Heater Current: 0.6  10% Ampere

Absolute Maximum Ratings

• Anode Input: 6 Watts (calculated as the product of the Anode No. 2 voltage and the average Anode No. 2 current)
• Anode No. 3 Voltage: 16,000 Volts dc
• Anode No. 2 Voltage: 8,000 Volts dc
• Anode No. 1 Voltage: 3,000 Volts dc
• Grid No. 1 Voltage:
  • Negative Bias Value: 300 Volts dc
  • Positive Bias Value: 0 Volts dc
  • Positive Peak Value: 2 Volts
• Peak Heater-Cathode Voltage:
  • Heater Negative with Respect to Cathode: 180 Volts
  • Heater Positive with Respect to Cathode: 180 Volts
• Peak Voltage Between Anode No. 2 and Any Deflecting Plate: 1500 Volts
• Ratio of Post Accelerator Voltage to Anode Voltage (Anode 3 to Anode 2): 2.5 maximum

Typical Operating Conditions

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

• Anode No. 3 Voltage: 9700 Volts dc
• Anode No. 2 Voltage: 6100 Volts dc
• Anode No. 1 Voltage (for Focus): 1510 to 2225 Volts dc
• Grid No. 1 Voltage (Required for Cutoff): -135 to -202 Volts dc (defined as the voltage required for visual extinction of the undeflected focused spot)
• Deflection Factors:
  • Deflecting Plates 1-2: 100 to 150 Volts dc/Inch
  • Deflecting Plates 3-4: 100 to 150 Volts dc/Inch
  • Note: Deflection plates 1 and 2 are positioned nearer to the screen.
• Modulation: 45 Volts maximum
• Line Width "A": 0.5 mm
• Line Width "B": 0.75 mm
• Focus Electrode Current: -25 to +25 A
• Undeflected Spot Position: Within a 20 mm square
• Note on Measurements: Modulation, line widths, and focus electrode current are measured in accordance with the MIL-E-1 specification at a post-accelerator current (IA3) equal to 25 A.

Maximum Circuit Values

• Grid No. 1 Circuit Resistance: 2.0 Megohms maximum
• Resistance in Any Deflection Plate Circuit: 5.0 Megohms maximum

Interelectrode Capacitances

The direct interelectrode capacitances of the 12ANP14 are approximately as follows: