Icom IC-2200H Service Manual

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Icom IC-2200H Service Manual Manual pdf 13 page image

4 - 54-3-3 REFERENCE OSCILLATOR CONTROLCIRCUIT (LOGIC AND MAIN UNITS)The reference oscillator control circuit changes the refer-ence frequency when using digital voice function.When digital voice signals output from the optional digitalvoice unit, the “REFMOD” signal outputs from it via the J4(pin 4) at the same time. The “REFMOD” signal is applied tothe amplifier (IC521, pin 3), and passes through the CTCSSswitch (IC524, pins 6 and 1). The signal is applied to the D/Aconvertor (MAIN unit; IC5, pin 13) via the “CTCSS” line. Theoutput signal from the D/A convertor (MAIN unit; IC5, pin 14)is applied to the reference oscillator (MAIN unit; X1) to con-trol the reference frequency while transmitting digital signalsas “DTC” line.4-4 POWER SUPPLY CIRCUITSVOLTAGE LINESDescriptionThe 13.8 V voltage from the connected DCpower supply.The same voltage as the HV line which is con-trolled by the HVSW circuit (Q28, Q30, Q31).When the [POWER] switch (LOGIC unit; S1) ispushed, the CPU (LOGIC unit; IC1, pin 40) out-puts the “PWRON” control signal to the powerswitching circuit to turn the circuit ON.Common 5 V for the CPU (LOGIC unit; IC1)converted from the HV line by the C5V regulatorcircuit (IC8). The circuit outputs the voltageregardless of the power ON/OFF condition.Common 8 V converted from the SWHV line bythe +8V regulator circuit (IC7).Common 5 V converted from the +8V line by the+5V regulator circuit (Q21, Q22).Transmit 8 V controlled by the T8 regulator cir-cuit (Q14, Q15) using the “TXC” signal from theI/O expander IC (IC2, pin 6). The voltage is con-verted from the +8V line at the regulator circuit.Receive 5 V controlled by the R5 regulator cir-cuit (Q25) using the “RXC” signal from the I/Oexpander IC (IC2, pin 5). The voltage is con-verted from the +5 V line at the regulator circuit.LineHVSWHVC5V+8V+5VT8R5VPinnumber23101114152223PortnameT3SQLATTFCSQLINDTCMODT2T1DescriptionOutputs RF tracking voltage whilereceiving.Outputs attenuator control signal.Outputs reference frequency controlvoltage.Outputs squelch control signal toadjust threshold level.Outputs DTCS slope correction signal.Outputs transmitting deviation controlsignal.Outputs RF tracking voltage whilereceiving.• Outputs RF tracking voltage whilereceiving.• Outputs transmitting power controlsignal while transmitting.4-5 PORT ALLOCATIONS4-5-1 D/A CONVERTER IC (MAIN UNIT; IC5)Pinnumber4561114PortnameAFMUTERXCTXCW/NSHIFTDescriptionOutputs AF mute control signal.High: While muting.Outputs R5 regulator (Q25) controlsignal.Low: While receiving.Outputs T8 regulator (Q14 and Q15)control signal.High: While transmitting.Outputs 2nd IF filter select signal([W/N] version ONLY).High: While wide passband width(±5.0 kHz) is selected (FI1 isselected).Low: While narrow passband width(±2.5 kHz) is selected (FI2 isselected).Outputs VCO regualtor (Q1, Q3, Q5,Q8, D1) control signal.Low: While transmitting.High: While receiving.4-5-2 EXPANDER IC (MAIN UNIT; IC2)