time the control grid voltage exerts its usual influence on the electron stream from cathode to plate. In the circuit, a capacitor (the grid condenser) couples a radio frequency signal (the carrier) to the control grid of an electron tube. The capacitor also facilitates development of dc voltage on the grid. The impedance of the capacitor is small at the carrier frequency and high at the modulating frequencies. A resistor (the grid leak) is connected either in parallel with the capacitor or from the grid to the cathode. The resistor permits dc charge to "leak" from the capacitor and is utilized in setting up the grid bias. At small carrier signal levels, typically not more than 0.1 volt, the grid to cathode space exhibits non-linear resistance. Grid current occurs during 360 degrees of the carrier frequency cycle. The grid current increases more during the positive excursions of the carrier voltage than it decreases during the negative excursions, due to the parabolic grid current versus grid voltage curve in this region. This asymmetrical grid current develops a dc grid voltage that includes the modulation frequencies. In this region of operation, the demodulated signal is developed in series with the dynamic grid resistance , which is typically in the range of 50,000 to 250,000 ohms. and the grid condenser along with the grid capacitance form a low pass filter that determines the audio frequency bandwidth at the grid. At carrier signal levels large enough to make conduction from cathode to grid cease during the negative excursions of the carrier, the detection action is that of a linear diode detector. Grid leak detection optimized for operation in this region is known as power grid detection or grid leak power detection. Grid current occurs only on the positive peaks of the carrier frequency cycle. The coupling capacitor will acquire a dc charge due to the rectifying action of the cathode to grid path. The capacitor discharges through the resistor (thus grid leak) during the time that the carrier voltage is decreasing. The dc grid voltage will vary with the modulation envelope of an amplitude modulated signal. The plate current is passed through a load impedance chosen to produce the desired amplification in conjunction with the tube characteristics. In non-regenerative receivers, a capacitor of low impedance at the carrier frequency is connected from the plate to cathode to prevent amplification of the carrier frequency. Design