Experimental Television Transmitter

Experimental Television Transmitter

This experimental television transmitter, featuring an innovative low-power Kerr cell modulator, provided a practical and accessible solution for early television experimenters. Its design addressed key technical challenges of the time and played an important role in the development and popularisation of television technology in the 1930s.

Purpose and Configuration

• Intended Use: The transmitter is designed solely for experimental purposes, supporting the transmission of low-definition television images at 30 lines, 12.5 pictures per second, with a 7:3 aspect ratio.
• Base Unit: Utilises a standard 16mm cinema projector, modified so that it passes two pictures per frame, resulting in 6.25 frames per second past the projector aperture.
• Scanning Mechanism: Employs a mechanical scanner in the form of a 30-hole disc, driven by a motor with an 8-pole phonic wheel. The motor is synchronised using 50-cycle AC mains, ensuring stable operation.
• Synchronisation: The synchronising gear is identical for both transmitter and receiver, guaranteeing perfect synchronism between transmitted and received images.

Electronic and Optical Components

• Amplification: Two amplifiers are included—a high-gain, battery-operated primary amplifier and a high-gain, compensated secondary amplifier. A third amplifier is recommended when the system is used with a mirror drum receiver for optimal efficiency.
• Photocell: Uses a Philips photocell for image pickup.
• Light Source: Illumination is provided by a 60-volt, 150-watt projection lamp.

Kerr Cell Modulator

• Manufacturer: British Television Supplies, Ltd. also produces a new type of Kerr cell for the system.
• Design Features: Two versions are available:
  • Standard: Requires a polarising voltage of 300 volts and modulates fully with a peak swing of 90 volts.
  • High-Voltage: Requires a polarising voltage of 400 volts and modulates fully with a peak swing of 140 volts.
• Cooling and Maintenance: The Kerr cell features a special glass chamber for the nitrobenzine, with a large radiating surface to dissipate heat rapidly. If efficiency drops due to nitrobenzine deterioration, the cell can be refilled at low cost. The cell is designed to plug into a valve socket for easy replacement. Nicol prisms are housed in a removable housing secured by an external collar.

This transmitter, described in Television & Shortwave World Jan 1936, Page 47, represents a typical, mechanically scanned experimental television setup of the era, emphasising simplicity, modularity, and ease of maintenance for amateur experimenters.

Vous pourrez trouver sous ce lien 14 modèles d'appareils, 8 avec des images et 0 avec des schémas.
Tous les appareils de BTS (B.T.S.) British Television Supplies; London