17BE3A — Compactron Single Damper Diode

The 17BE3A is a specialized Compactron, single heater-cathode type diode designed primarily for use as a damping diode in the horizontal deflection circuits of color television receivers. It features a coated unipotential cathode and is housed in a T-9 glass envelope.

The 17BE3A is electrically identical to the 6BE3A and 12BE3A, differing only in its heater characteristics and ratings. Additionally, the 17BE3A offers a lower tube voltage drop compared to the older 17BE3.

Mechanical Construction and Pinout

The 17BE3A utilizes a T-9 glass envelope with a JEDEC 9-60 outline and a 12-pin button base (JEDEC E12-70). The tube is designed to be mounted in any position.

Physical Dimensions

• Maximum Overall Length: 2.875 inches
• Seated Height: 2.250 to 2.500 inches
• Body Diameter: 1.062 to 1.188 inches

Pin Connections (JEDEC 12GA Basing Diagram)

The 12-pin layout provides the following connections:

• Pin 1: Heater (H)
• Pin 2: No Connection (NC)
• Pin 3: No Connection (NC)
• Pin 4: Plate (P) or Internal Connection (IC)
• Pin 5: Internal Connection (IC)
• Pin 6: No Connection (NC)
• Pin 7: Cathode (K)
• Pin 8: No Connection (NC)
• Pin 9: Internal Connection (IC)
• Pin 10: Plate (P)
• Pin 11: No Connection (NC)
• Pin 12: Heater (H)

Note on Socket Wiring: Socket terminals 5, 6, 8, and 9 must not be used as tie points for external circuitry. It is recommended that the socket clips for these specific pins be physically removed to prevent accidental contact or voltage breakdown.

Heater and Heater-Cathode Ratings

The 17BE3A is designed for series-string heater circuits, featuring controlled warm-up characteristics.

The heater warm-up time is defined as the time required for the heater voltage to reach 80% of its rated value when four times the rated heater voltage is applied to a circuit consisting of the tube heater in series with an external resistance equal to three times the nominal heater operating resistance.

Heater-Cathode Voltage Limits (Design-Maximum Values)

To prevent insulation breakdown, the voltage difference between the heater and cathode must be kept within strict limits:

• Heater Negative with Respect to Cathode:
  • DC Component: 900 V maximum
  • Total DC and Peak: 5000 V maximum
• Heater Positive with Respect to Cathode:
  • DC Component: 100 V maximum
  • Total DC and Peak: 300 V maximum

Electrical Characteristics and Maximum Ratings

The 17BE3A is rated under the Design-Maximum System (EIA Standard RS-239) for television damper service.

Direct Interelectrode Capacitances

These approximate values are measured without an external shield:

• Cathode to Plate and Heater [K to (P + H)]: 10 pF
• Plate to Cathode and Heater [P to (K + H)]: 8.0 pF
• Heater to Cathode [H to K]: 3.4 pF

Typical Operating Characteristics

• Tube Voltage Drop: 22.5 V (measured at a DC plate current of 350 mA)

Television Damper Service Maximum Ratings

These ratings apply to operation in a standard 525-line, 30-frame television system (FCC standards):

• Peak Inverse Plate Voltage: 5000 V maximum
• Plate Dissipation: 6.5 W maximum
• Steady State Peak Plate Current: 1200 mA maximum
• DC Output Current: 200 mA maximum
• Pulse Duty Cycle Limit: The duty cycle of the voltage pulse must not exceed 15% of one horizontal scanning cycle.

Technical Summary

The 17BE3A is a high-voltage Compactron damper diode designed for television horizontal deflection circuits. Operating with a 16.8 V, 450 mA heater, it provides robust insulation capable of withstanding peak heater-cathode potentials up to 5000 V. With a low typical voltage drop of 22.5 V at 350 mA and a peak inverse plate voltage rating of 5000 V, it offers efficient and reliable performance in demanding television receiver applications.