3-4 ANTENNA TUNER CIRCUITS3-4-1 MATCHING CIRCUIT (TUNER UNIT)The matching circuit is a T-network. Using 2 tuning motors,the matching circuit obtains rapid overall tuning speed.Using relays (RL1–RL15), the relay control signals from theantenna tuner CPU (CTRL unit; IC5) via the buffer-amplifier(IC1, IC2) ground one of the taps of L3–L12 and add capacitors(C27–C43). After selecting the coils and capacitors, 2motors (CTRL unit; MF1, MF2) adjust C44 and C45 usingthe antenna tuner CPU (CTRL unit; IC5) and the motor controller(CTRL unit; Q211–Q218, D211–D217) to obtain a lowSWR (Standing Wave Ratio).3-4-2 DETECTOR CIRCUIT (CTRL UNIT)(1) SWR detectorForward and reflected power are picked up by a currenttransformer (L1), detected by D2 and D1, and then amplifiedat IC1a and IC1b, respectively. The amplified voltages areapplied to the antenna tuner CPU (IC5, pins 2, 3). The tunerCPU detects the SWR.(2) Reactance components detectorReactance components are picked up by comparing thephases of the RF current and RF voltage. The RF current isdetected by L4 and R16 and buffer-amplified at IC14e andIC2a and then applied to the phase comparator (IC3a). RFvoltages are detected by C12–C14 and then applied to thephase comparator (IC3b) after being amplified at the bufferamplifiers(IC14c, IC2b). The output signal from the phasecomparator (IC3a, pin 6 for RF current, IC3b pin 7 for RFvoltage) is rectified at D7 and D6 for conversion into DC voltage.The rectified voltage signals are combined, then amplifiedat the inverter amplifier (IC4b), then applied to theantenna tuner CPU (IC5, pin 64).