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Figure 3-5B.—Series-diode detector and wave shapes. RF INPUT SIGNAL.
Figure 3-5C.—Series-diode detector and wave shapes. RECTIFIED SIGNAL.
Figure 3-5D.—Series-diode detector and wave shapes. AUDIO SIGNAL.
Series-Diode Detector
Let’s analyze the operation of the circuit shown in view (A) of figure 3-5. This circuit is the basic
type of diode receiver and is known as a SERIES-DIODE DETECTOR. The circuit consists of an
antenna, a tuned LC tank circuit, a semiconductor diode detector, and a headset which is bypassed by
capacitor C2. The antenna receives the transmitted rf energy and feeds it to the tuned tank circuit. This
tank circuit (L1 and C1) selects which rf signal will be detected. As the tank resonates at the selected
frequency, the wave shape in view (B) is developed across the tank circuit. Because the semiconductor is
a nonlinear device, it conducts in only one direction. This eliminates the negative portion of the rf carrier
and produces the signal shown in view (C). The current in the circuit must be smoothed before the
headphones can reproduce the af intelligence. This action is achieved by C2 which acts as a filter to
