PHANTASTRON AFC

Description: A pentode operates as an astable phantastron during radar search and functions as a direct current amplifier during lock-on, providing direct control of the klystron repeller.

The pentode is a type of vacuum tube with five active elements, which enhances its functionality in various electronic circuits. In the context of radar systems, the pentode serves a dual purpose. During the radar search phase, it operates as an astable phantastron, a configuration that generates a continuous square wave output. This output is critical for producing the necessary timing signals in radar applications, allowing for efficient scanning and detection of targets.

When the radar system transitions to the lock-on phase, the role of the pentode shifts to that of a direct current amplifier. In this capacity, it amplifies the low-level signals received from the radar return, ensuring that the signals are strong enough to effectively control the klystron repeller. The klystron, a specialized vacuum tube used to generate microwave signals, relies on precise control of its repeller voltage to modulate the output frequency and power. The pentode's ability to furnish this direct control is essential for maintaining the stability and accuracy of the radar system during target tracking.

The design of circuits utilizing a pentode requires careful consideration of biasing, load resistance, and frequency response to ensure optimal performance in both modes of operation. Proper implementation of the pentode within the radar system can significantly enhance its effectiveness, providing reliable performance in various operational scenarios.Pentode is astable phantastron during radar search, and d-c amplifier during lock-on when pentode furnishes direct control of klystron repeller. -NBS, "Handbook Preferred Circuits Navy Aeronautical Electronic Equipment, " Vol. 1, Electron Tube circuits, 1963, p N13-6