0Y4G — Half-Wave Gas Rectifier

The 0Y4G (also designated as 0Y4 or 0Y4-G) is a cold-cathode, ionically heated gas rectifier tube designed for half-wave rectification. It features an auxiliary starter anode, enabling direct operation from standard 117-volt AC or DC power lines without requiring a separate filament heating supply.

Physical Specifications and Pinout

The 0Y4G is constructed with an ionically heated emitter (cold cathode) housed in a T-7 glass bulb. It utilizes an octal 5-pin dwarf base and is designed to be mounted in any physical orientation.

Physical Dimensions

• Bulb Type: T-7
• Base Type: Octal 5-pin dwarf
• Maximum Diameter: 1 5/64 inches
• Maximum Seated Height: 2 1/16 inches
• Maximum Overall Length: 2 5/8 inches
• Mounting Position: Any

Pin Connections and Basing Diagram

The tube utilizes the 4BU base connection configuration. Although pins 7 and 8 are labeled as filament connections, the tube operates as a cold-cathode device, and these two pins must be connected together externally.

Electrical Ratings and Operating Conditions

The 0Y4G is rated for half-wave rectifier service utilizing a condenser-input filter. The electrical limits and typical operating parameters are defined as follows:

Absolute Maximum and Minimum Ratings

• Maximum Inverse Peak Voltage: 300 V
• Maximum Peak Current: 500 mA
• Maximum DC Output Current: 75 mA
• Minimum DC Output Current: 40 mA
• Minimum Series Anode Resistance (for 117-Volt Line Operation): 50 ̩
• Maximum DC Starting Voltage: 95 V
• Approximate Tube Drop: 12 V

Circuit and Operating Requirements

To ensure reliable starting and stable operation, the following circuit conditions must be maintained:

• Starter Anode Circuitry: The starter anode (Pin 3) must be connected to the main anode (Plate, Pin 5) through a 10-megohm resistor. This resistor must be bypassed with a 0.002 µF condenser. Under these conditions, the maximum DC starting voltage is 95 volts.
• Filament Jumper: Pins 7 and 8 must be connected together externally.
• Current Limiting: When operating directly from a 117-volt line, a minimum series anode resistance of 50 ohms is required to limit the peak current.
• Operational Constraints: Rapid intermittent operation of the tube is undesirable and should be avoided to prevent premature degradation or failure.

Technical Summary

The 0Y4G is an octal, cold-cathode, half-wave gas rectifier featuring an ionically heated emitter and a starter anode. Designed to operate directly from a 117-volt AC or DC line, it eliminates the need for a dedicated filament transformer. It supports a maximum peak current of 500 mA and a maximum DC output current of 75 mA, with a minimum current threshold of 40 mA required to sustain conduction. With an approximate operating tube drop of 12 volts and a compact T-7 dwarf octal form factor, the 0Y4G provides a highly integrated solution for line-voltage rectification where simplicity and cold-cathode operation are desired.