1960 — Protective Tube
The RCA-1960 is a specialized, voltage-sensitive protective tube designed to safeguard electrical circuits. Housed in a T10-1/2 glass envelope with a unique terminal configuration, the device is engineered to provide reliable voltage-limiting and breakdown performance under varying environmental conditions.
Mechanical Construction and Mounting
The RCA-1960 features a robust physical design optimized for high-voltage protection systems. It is constructed with a T10-1/2 bulb envelope and utilizes a cap and flange terminal arrangement instead of a conventional pinned base.
The physical dimensions of the device are specified as follows:
- Maximum Overall Height: 2-15/16" ± 1/8"
- Maximum Diameter: 1.920" (inclusive of the flange assembly)
- Maximum Flange Diameter: 1-3/8"
- Cap Diameter: 0.360" ± 0.005"
Due to its cap and flange terminal configuration, the tube requires a special mounting arrangement. It is rated for operation in any mounting position, allowing for versatile integration into diverse equipment layouts.
Electrical Characteristics and Breakdown Behavior
The electrical performance of the RCA-1960 is characterized by its breakdown thresholds and voltage drop when operated on a 60-cycle sine-wave supply. The tube exhibits a low interelectrode capacitance of 1.35 μμf.
When subjected to a 60-cycle supply, the tube's electrical parameters are defined by the following limits:
- Minimum Peak Supply Voltage: 425 V
- Maximum Peak Initial Breakdown Voltage (Cold Tube): 425 V
- Maximum Peak Recurrent Breakdown Voltage: 285 V (at a tube current of 30 mA)
- Tube Voltage Drop: 175 V (at a tube current of 30 mA)
The initial breakdown voltage represents the peak potential required to initiate conduction when the tube is cold, which is capped at a maximum of 425 V. Once conduction is established, the recurrent breakdown voltage required to maintain or re-initiate conduction on subsequent cycles drops to a maximum of 285 V at a current of 30 mA. During active conduction at this same 30 mA current level, the voltage drop across the tube stabilizes at a nominal 175 V.
Application and Operating Considerations
The primary intended application of the RCA-1960 is as a protective tube. It acts as a voltage-clamping or shunt device to protect sensitive downstream components from transient overvoltage conditions.
Temperature Independence
A key operational feature of the RCA-1960 is its stability under varying environmental conditions. Normal variations in ambient temperature have a negligible effect on the tube's breakdown and conduction performance, ensuring consistent protection across a wide thermal operating range.
Arc Prevention Limitation
When designing circuits incorporating the RCA-1960, engineers must observe a critical operating limitation: the energy dissipated in the tube must not be sufficient to establish a sustained arc. A sustained arc can lead to thermal runaway, permanent damage to the tube, or a failure of the protective function. Consequently, the external circuit must be designed to limit the duration and magnitude of the current passing through the tube during a breakdown event.
Technical Summary
The RCA-1960 is a T10-1/2 bulb, cap-and-flange protective tube designed for voltage-limiting applications. It features an interelectrode capacitance of 1.35 μμf and can be mounted in any position using a special mounting interface. Under 60-cycle sine-wave supply conditions, the tube is characterized by a minimum peak supply voltage of 425 V, a maximum cold initial breakdown voltage of 425 V, a maximum recurrent breakdown voltage of 285 V at 30 mA, and a conducting voltage drop of 175 V at 30 mA. The device offers excellent thermal stability, with normal ambient temperature variations having a negligible effect on performance, provided that circuit design prevents the dissipation of energy from establishing a sustained arc.
