12ANP1 — Electrostatic Focus and Deflection Cathode-Ray Tube

The 12ANP1 is a 12-inch, direct-viewed, round glass cathode-ray tube designed primarily for oscilloscope applications. It features electrostatic deflection, electrostatic focus, and post-deflection acceleration to achieve high-brightness displays. The tube incorporates an aluminized screen and a gray filter glass faceplate to enhance contrast and readability under ambient light.

Phosphor Options and Screen Characteristics

The 12ANP1 can be supplied with several different screen phosphors depending on the application requirements. The primary documented phosphors include:

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

Electrical and Interelectrode Capacitance Data

The 12ANP1 utilizes an indirectly heated cathode. The heater is designed for AC or DC operation with the following nominal characteristics:

• Heater Voltage: 6.3 V
• Heater Current: 0.6 ± 10% A

Direct Interelectrode Capacitances

The approximate direct interelectrode capacitances of the tube's structures are:

Mechanical Specifications and Basing

The physical construction of the 12ANP1 is characterized by a round glass bulb with specialized external contacts to accommodate high-voltage operation and deflection signals.

• Overall Length: 22 1/2 ± 3/8 inches
• Bulb Diameter (Face): 12 7/16 +1/16 -3/32 inches
• Neck Diameter: 2 3/16 ± 1/16 inches
• Base: Medium Shell Diheptal 12-Pin (B12-37)
• Basing Arrangement: 14AW
• Bulb Contact: Recessed Small Cavity Cap (J1-22)
• Neck Contacts: Small Ball Caps (J1-25)

Alignment and Deflection Geometry

Precise mechanical alignment is maintained during manufacturing to ensure predictable trace orientation:

• 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 (Anode No. 2) 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.

Applying a positive voltage to deflecting plate D1 deflects the electron beam approximately away from the Anode No. 2 neck contact. Applying a positive voltage to deflecting plate D3 deflects the beam approximately away from the post-accelerator button (J1-22).

Absolute Maximum Ratings

The following absolute maximum ratings must not be exceeded under any operating conditions:

Note: Anode input is calculated as the product of the Anode No. 2 voltage and the average Anode No. 2 current.

Typical Operating Conditions

For standard applications, the following typical operating parameters are established:

• Anode No. 3 Voltage: 9,700 V DC
• Anode No. 2 Voltage: 6,100 V DC
• Anode No. 1 Voltage (for Focus): 1,510 to 2,225 V DC
• Grid No. 1 Voltage (for Cutoff): -135 to -202 V DC (for visual extinction of an undeflected focused spot)
• Deflection Factors (Plates 1–2): 100 to 150 V DC/inch
• Deflection Factors (Plates 3–4): 100 to 150 V DC/inch
• Modulation: 45 V Max (measured at a post-accelerator current of 25 µA)
• Line Width 'A': 0.5 mm (measured at a post-accelerator current of 25 µA)
• Line Width 'B': 0.75 mm (measured at a post-accelerator current of 25 µA)
• Focus Electrode Current: -25 to +25 µA
• Undeflected Spot Position: Within a 20 mm square centered on the tube face

Deflection plates 1 and 2 are positioned nearer to the screen than plates 3 and 4, which influences their relative deflection sensitivity and capacitance.

Circuit Design Values

To ensure stable operation and prevent damage to the tube's electrodes, the external circuit impedances must be kept within the following limits:

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