1110 — Gas-Filled Double-Anode Rectifying Valve

The 1110 is a gas-filled, double-anode rectifying tube designed primarily for low-voltage battery charging applications. Manufactured with an oxide-coated filament, this directly heated valve is engineered to deliver efficient rectification in battery chargers, supporting charging currents up to 2 A per valve and configurations of up to 20 lead-acid (Pb) cells.

Construction, Physical Specifications, and Base

The 1110 features a robust glass envelope containing two independent anodes and a shared directly heated filament. The physical dimensions and mechanical specifications of the tube are as follows:

• Maximum Bulb Diameter: 39 mm
• Maximum Seated Height: 113 mm
• Maximum Overall Length: 131 mm
• Net Weight: 55 g
• Shipping Weight (per 100 valves): 7100 g

Mounting and Socketing

To ensure stable operation and proper distribution of the gas fill during conduction, the tube must be mounted in a vertical, base down position. It utilizes a specialized Type A base and requires a Type 40465 socket for electrical connection. The pinout configuration includes connections for the filament ($f, f$) and both anodes ($a, a'$).

Filament and Heating Characteristics

The 1110 is equipped with a directly heated, oxide-coated filament. The filament supply must be alternating current (A.C.) with the following nominal ratings:

The recommended pre-heating time of 15 seconds allows the filament to reach its proper operating temperature before anode current is drawn. In urgent circumstances, this pre-heating period may be decreased to 0 seconds.

Electrical and Typical Characteristics

As a gas-filled device, the 1110 exhibits a low and relatively constant voltage drop during conduction, which contributes to its high efficiency in low-voltage rectification. Its typical characteristics are defined by:

• Arc Voltage ($V_{\text{arc}}$): 9 V (the typical voltage drop across the tube during conduction)
• Ignition Voltage ($V_{\text{ign}}$): 16 V (the minimum anode voltage required to initiate ionization and start conduction)

Operating Characteristics in Battery Charging Service

In a typical full-wave rectification circuit (designated as circuit "a"), operating with a transformer secondary voltage ($V_{\text{tr}}$) of 60 Veff (RMS) and a series limiting resistance ($R_t$) of 8 $\Omega$, the tube's performance varies dynamically with the state of charge of the connected battery bank:

Current Regulation with a Barretter

When a barretter (current regulator) is incorporated into the charging circuit, the nominal charging current ($I_o$) can be increased from its standard nominal value of 1.4 A up to 2.0 A. This allows for a more rapid and constant charging profile.

Limiting Values (Absolute Maximum System)

To prevent damage to the oxide-coated filament and ensure the integrity of the gas fill, the operating conditions must be kept within the following absolute limits:

• Maximum Peak Inverse Anode Voltage ($V_{\text{ainv}_p}$): 185 V
• Maximum Average Anode Current ($I_a$): 0.85 A
• Maximum Peak Anode Current ($I_{\text{ap}}$): 5.0 A
• Minimum Series Resistance ($R_t$): 4 $\Omega$
• Ambient Temperature Range ($t_{\text{amb}}$): -55 °C to +75 °C

The minimum series resistance ($R_t$) of 4 $\Omega$ is a critical safety parameter required to limit the peak anode current and protect the tube from excessive current surges during startup or transient conditions.