Kenwood NXR-700 Service Manual

Also see for NEXEDGE NXR-700: Brochure Instruction manual Service manual Instruction manual Instruction manual

Contents

NXR-700133-3. Forward/Reflect power detector circuitThe forward / Reflect power detector circuit consists ofa CM coupling type detection circuit formed by a Micro stripline and the differential amplifi er IC4.A part of the transmitter power is detected by diodes D9and D10 and is converted into DC voltage.ATTIC4Diff. AMP D10DETATTD9DETReflectFowardDirectional couplerFig. 10 Forward/Reflect power detector circuit3-4. Harmonic filter circuitThe harmonic filter circuit uses a three-stage “pi” typeChebyshev type LPF.This circuit removes harmonics from the transmitter out-put and sends the filtered signal to the antenna connecter(CN22).3-5. APC circuitThe APC circuit stabilizes the transmitter power so thatthe output power specified by the Control Voltage from theMPU is obtained. It consists of a Forward/Reflect power de-tector circuit and Differential amplifi ers (IC2 and IC5).It compares the voltage detected by the Forward/Reflectpower detector circuit (voltage detected by the ForwardPower) and the Control Voltage (PWR_CONT) from theMPU (IC802: X56-311 A/3). It stabilizes the output power bychanging pin 2 (Vgg).The voltage detected (that detected Reflect Power) bythe Forward/Reflect power detector circuit is compared tothe Control Voltage (PWR_PRT) from the MPU (IC802:X56-311 A/3). When a load V.S.W.R. is connected to theAntenna Connecter and is more than 1.5, it functions so thatthe output power gets smaller as the detection voltage (thatdetected Refl ect Power) gets larger.3-6. High temperature detector circuitThe high temperature detector circuit consists of a ther-mal switch IC (IC7) and a switching FET (Q2).This circuit lowers the transmitter power when the finalunit temperature is too high (90°C or higher).Q2SWPoutVDDVGGPinIC10RA60H1317M1AIC7TempprotectionICFig. 12 High temperature detector circuitATTIC4Diff. AMPD10DETATTD9DETReflectFowardIC5Add. AMPDiff. AMPIC2Diff. AMPDirectional couplerHPFPoutVDDVGGPinIC10RA60H1317M1A+PWR_PRTPWR_CONTFig. 11 APC circuitCIRCUIT DESCRIPTION