17BE3 — Half-Wave Vacuum Rectifier

The 17BE3 (also designated as the 17BZ3) is a compactron-type, indirectly heated half-wave vacuum rectifier designed specifically for service as a damping diode in the horizontal-deflection circuits of both color and black-and-white television receivers. It features a single diode structure with a coated unipotential cathode and is designed to operate in any mounting position.

The 17BE3 is electrically identical to the 6BE3, 12BE3, and 6BZ3 vacuum tubes, differing only in its heater ratings and characteristics.

Mechanical Specifications and Pinout

The 17BE3 is housed in a T-9 glass bulb (JEDEC 9-60 outline) with a button 12-pin E12-70 base, commonly referred to as a duodecar or compactron type. This configuration requires a specialized duodecar 12-contact socket.

Physical Dimensions

• Maximum Overall Length: 2.875 to 3.110 inches
• Seated Height: 2.250 to 2.735 inches
• Diameter: 1.062 to 1.188 inches

Pin Connections (JEDEC 12GA)

Depending on the specific manufacturing design of the 12GA basing diagram, two pinout configurations are documented. In both configurations, certain pins are designated as internal connections (IC) or no-connection (NC) terminals. It is recommended that socket terminals for pins 5, 6, 8, and 9 not be used as tie points, and ideally, the socket clips for these pins should be removed to prevent electrical interference or breakdown.

Pinout Configuration A

Pinout Configuration B

Heater Characteristics

The 17BE3 is engineered with a controlled heater warm-up characteristic, which is critical for minimizing heater voltage surges when the tube is operated in series-connected heater strings.

• Heater Voltage (AC or DC): 16.8 V
• Heater Current: 0.45 A to 0.46 A (nominal range of 0.45 ± 0.03 A)
• Average Heater Warm-up Time: 11 seconds

The heater warm-up time is defined as the time required for the heater voltage to reach 80% of its rated value when a voltage equal to four times the rated heater voltage (67.2 V) is applied to a test circuit. This test circuit consists of the tube heater connected in series with an external resistance equal to three times the nominal heater operating resistance (calculated as three times the rated voltage divided by the rated current).

Electrical Characteristics and Capacitances

Under typical operating conditions, the 17BE3 exhibits a low internal tube voltage drop, which ensures efficient power transfer in television deflection circuits.

• Tube Voltage Drop: 25 V (measured as an instantaneous value at a direct current plate current of 350 mA)

Direct Interelectrode Capacitances

The direct interelectrode capacitances of the tube, measured without an external shield, vary slightly depending on the internal structural layout:

Capacitance Set A

• 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

Capacitance Set B

• Plate to Cathode and Heater: 10 pF
• Cathode to Heater and Plate: 8.0 pF
• Heater to Cathode: 3.4 pF

Maximum Ratings for Television Damper Service

The ratings for the 17BE3 are defined under the Design-Maximum System (EIA Standard RS-239). These limits are specified for operation in a standard television receiver utilizing a 525-line, 30-frame scanning system. Under these conditions, the horizontal voltage pulse duty cycle must not exceed 15% of a single horizontal scanning cycle, with a maximum pulse duration of 10 microseconds.

Heater-Cathode Voltage Limits

Because the damper diode operates at high potentials relative to ground, the insulation between the heater and the cathode is subjected to severe electrical stress. The maximum allowable heater-cathode voltages are:

• Heater Negative with Respect to Cathode:
  • DC Component: 900 V
  • Total DC and Peak: 5000 V
• Heater Positive with Respect to Cathode:
  • DC Component: 100 V
  • Total DC and Peak: 300 V to 3000 V (depending on the specific manufacturing specification and rating system applied)

Technical Summary

The 17BE3 is a specialized compactron/duodecar half-wave vacuum rectifier designed for high-voltage television damper service. Operating with a 16.8 V heater drawing 0.45 A to 0.46 A, it features a controlled 11-second warm-up time to protect series-wired heater strings. Physically housed in a T-9 glass envelope with a 12-pin button base, it provides robust performance under demanding horizontal-deflection conditions, supporting a peak inverse plate voltage of 5000 V, a peak plate current of 1200 mA, and a plate dissipation of 6.5 W. Its low internal voltage drop of 25 V at 350 mA ensures highly efficient operation in television receiver circuits.