(from TM 11-866)
16. SECOND DETECTOR. -- The 2nd detector (V8) is a twin diode operated with both plates and both cathodes connected in parallel. Its IF input is obtained from the untuned secondary of coil L32 in transformer T4 in the plate circuit of the 3rd IF ampli- fier (V7). To facilitate operation of the LIMITER tube (V9) the diode load resistance totaling 475,000 ohms is divided into two approximately equal parts. One part, 250,000 ohms (R30), is placed between the paralleled cathodes and ground and is by-passed (for IF) by a 50 micromicrofarad capacitor (C26). The other part, totaling 225,000 ohms is between the low-potential end of the secondary and ground, and is made up of 100,000 ohms (R48), 75,000 ohms (R24), and 50,000 ohms (R25). The 100,000 ohm resistor (R48), together with two 50 micromicrofarad capacitors (C44, C45), constitute a filter to prevent IF voltages from reaching the 50,000 ohm resistor (R25) and the AUDIO GAIN control (R26).
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