Motorola IC-T81E, IC-T81A service manual Receiver, Band, Wfm, Except spurious points typical values

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M RECEIVER

• Receiver system	: Double-conversion superheterodyne
• Intermediate frequency	: 1st	69.45 MHz (13.35 MHz: WFM)
	2nd	450 kHz
• Sensitivity*	: (except spurious points; typical values)

		Band	FM	AM	WFM
		50 MHz	0.18 µV	0.56 µV	–
		144 MHz	0.18 µV	–	–
		440 MHz	0.18 µV	–	–
	1200 MHz		0.25 µV	–	–
		91.5 MHz	–	–	2.0 µV

*FM and WFM are measured at 12 dB SINAD, AM is measured at 10 dB S/N.

• Squelch sensitivity	: 50, 144, 440 MHz	Less than 0.18 µV (Threshold)
	1200 MHz	Less than 0.25 µV (Threshold)
	AM (50 MHz only)	Less than 0.56 µV (Threshold)
	WFM	Less than 5.6 µV (Threshold)
• Selectivity (except WFM)	: More than 15 kHz/–6 dB
	Less than 30 kHz/–60 dB
• Spurious and image rejection ratio	: 50, 144 MHz	More than 60 dB
	440 MHz	More than 50 dB
	1200 MHz	More than 38 dB
	(except half IF, 2nd image, 50 MHz band IF and WFM)
• Audio output power	: 250 mW typical at 10 % distortion with an 8 Ω load

All stated specifications are subject to change without notice or obligation.

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Contents Multiband FM Transceiver Ordering Parts IntroductionRepair Notes Sample OrderTable of Contents General SpecificationsTransmitter Version 50 MHz 145 MHz 440 MHz 1200 MHz MHz RX onlyBand ReceiverWFM WFMLogic Unit Inside ViewsRF Unit CPURemoving the Chassis Panel Removing the Shield Plate Disassembly InstructionsRemoving the Logic Unit Removing the RF Unit Logic unitCircuit Description Antenna Switching Circuits RF UnitReceiver Circuits Duplexer Circuit RF Unit7 1ST Mixer Circuit RF Unit Transmitter Circuits APC Circuits RF Unit DRIVE/POWER Amplifier Circuits RF UnitMHz PA APC Control CircuitPLL Circuits Power Supply Circuits Voltage LineLine Description VCC1 I/O Expander IC RF Unit IC2 Port Allocations2 I/O Expander IC RF Unit IC3 Pin Port Description Number NameCPU Logic Unit IC1 Preparation Adjustment Procedures‘ Required Test Equipment ConnectionPLL Adjustment ULV RF Unit Bottom ViewVLV RF Unit TOP View 6MLVDial Receiver AdjustmentSensitivity VHFLogic Unit TOP View SSG MeterTop Push and hold MHz band 101 dBmPush and hold Displayed frequency445.000 MHz USA-1 SQL keyTransmitter Adjustment HPF OFF LPF DeviationDtmf AUS, SEA=Surface mount Parts ListTrimmer Ceramic ECUE1H121JCQ Transistor UN911D TX Coil Eljnd R10J 0.1U Themistor Ceramic ECUE1H060CCQ Ceramic ECUE1H390JCQ VCO Board Ceramic ECUE1H120JCQ Accessories Mechanical Parts and DisassemblyChassis Parts VCO UnitMP29 C Diodes SEMI-CONDUCTOR InformationTransistor and FET’S TOP View Board LayoutsLogic Unit IC1 Bottom ViewIC3 GND Pset IfinIC6 RF UnitL912 J4 to Logic unit J1IC2 MP1IC3 J302 to RF unit VCO BoardOUT 12VCOOUT VLVCO3 VHF GND VHVCO3 UVCO3 Uhfout GND 12VCO3 GNDQ354 Block Diagram TX/RX Frequency Mode Xtal BPF PDA2, CK AMPTX/RX Buff ANT LPF HPF AMPMode Xtal Initial BPF ResetMOD TX/RX Frequency ANT Buff HPF LPF YGRLogic Unit Section Voltage DiagramOscin Mixin Oscout GND Mixout REC VCC DET Ifin Rssi 2NDLODEC Ifout Filout Quad WFM NTCCF20124AH 473KCT TXCCOM3 COM2 Reset Power 12VCO COM2 ResetClonein VCC VIN Cpuhv COM4 COM3 COM2 COM1VHF RF Unit400M 1200M00M 50M1200MHz 400MHzPLST1 IN1 GND1ENB VCC2 LOK GND2Icom America Inc Icom Inc 5566I-S