102L — Filamentary Triode

The 102L is a filamentary-type triode designed for use as an audio-frequency voltage amplifier or modulator. Developed by Bell Telephone Laboratories, the tube was manufactured by Western Electric and standardized for use in telecommunication systems.

Design and Construction

The 102L is a directly heated (filamentary) triode. In this design, the filament serves directly as the electron-emitting cathode. The tube is constructed with a glass envelope and a base designed for integration into standard communication equipment.

The filament operating specification is:

• Filament Current: 250 milliamperes

Electrical Characteristics and Ratings

The electrical design of the 102L is optimized for voltage amplification. Its key electrical parameters and maximum ratings are:

• Amplification Factor: 30
• Maximum Plate Voltage: 180 volts

With an amplification factor of 30, the 102L is capable of providing significant voltage gain in audio-frequency circuits. The maximum plate voltage rating of 180 volts represents the upper limit for safe operation of the anode.

Applications and Standardization

The 102L was developed by Bell Telephone Laboratories, the research laboratories of the American Telephone and Telegraph Company (A.T.&T.) and the Western Electric Company. It was standardized under Bell System Practices for transmission engineering.

The tube is designed for two primary classes of service:

• Audio-Frequency Voltage Amplification: For boosting low-level audio signals in transmission and amplification systems.
• Modulator Service: For signal modulation in communication applications.