Figure 6.21 Typical IF Amplifier used in Pocket Radios. Plus 12 volts is at the top and ground is at the bottom. The plus 12 volt line is bypassed to ground by a 0.1 u f capacitor. The circuit begins on the left with a transistor IF transformer. There are two of them in this diagram but it will be described in detail only once. The primary is tuned to resonance by a fixed resonating capacitor. The inductance of the coil is adjusted by means of a ferrite slug. The primary has a tap which is closer to the bottom than to the top. The capacitor connects across the entire primary. The secondary has many fewer turns than the primary and has no resonating capacitor. On the left, no connections to the primary are shown. The top of the secondary connects to the base of the only transistor in the circuit, an N P N BJT. The bottom of the secondary goes to ground through the parallel combination of a 36 k ohm resistor and a 0.1 u f capacitor. The bottom of the secondary also connects through a 27 k ohm resistor to plus 12 volts. The emitter of the transistor goes to ground through the parallel combination of a 6.2 k ohm resistor and a 0.1 u f capacitor. The collector connects to the bottom of another IF transformer. The tap goes to plus 12 volts. The top goes through a capacitor, typically 5 p f to the base of the transistor. The secondary of this transformer is shown as not connected to anything. End verbal description. Go back.