Samsung SCH-1500 series Service Manual

Also see for SCH-1500 series: User guide

Samsung Electronics 6-76-4 Transmitter Section (For PCS)POWER AMPPower Amp module (U550) amplifier signal to besent out to the base station through the antenna.DRIVER AMPThe driver amp (U522) allows the signal input tothe Power Amp module (U550) to be within aspecified level.UP CONVERTER (MIXER)The up converter (U521) receives the first localsignal to generate 1880±30 MHz from the signalcontrolled by TX AGC amp (U501). 1880 ±30 MHzsignal comes out from the mixer output by adding130MHz IF signal to 1750±30MHz first local signal.The driver amp’s reference number is U522 and upconverter’s reference number is U521.IF AUTOMATIC GAIN CONTROLLER AMPThe signal out to BBA (Base Band Analog) shouldbe a constant level. The TX IF AGC amp (U501)controls power to keep the signal at a constant level.Dynamic range is 85dB, up gain -40dB, and downgain -45dB.ANTENNAANT allows signal to send to receive from the basestation.RF BAND PASS FILTER (BPF)The RF BPF (F522, F521) accepts only specificfrequency (1880±30MHz) to send it out to powerand Power Amp module. The band width is60MHz.ISOLATORIsolator (U542) is used to reduce a reflected signal toprotect the power amp module from beingdamaged.POWER SUPPLY REGULATORThe power supply regulator (U751, U130) supply aregulated power to each part of transmitter. U130supplies 4.8V to Power Amp module (U550). U751supplies 4.2V to the others.Circuit Description