Page 2
8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver. Icom, Icom Inc. and logo are registered trademarks of Icom Incorporated (Japan) in the United States, the United Kingdom, Germany, France, Spain, Russia and/or other countries.
SECTION 1 SPECIFICATIONS GENERAL • Frequency coverage : TX 156.025–157.425 MHz 156.050–163.275 MHz • Type of emission : 16K0G3E, 16K0G2B (DSC) : 50 Ω (Nominal) • Antenna impedance • Operating temperature range : –4˚F to +140˚F • Power supply requirement : 13.8 V DC ±15% (negative ground) •...
Page 5
• CHANNEL LISTS . y l , s l y l l c i l 1 - 2...
SECTION 3 DISASSEMBLY INSTRUCTIONS • • REMOVING THE CASE REMOVING THE MAIN UNIT 1 Unscrew 4 screws, A. 1 Disconnect W2 from the J2 and J3. 2 Disconnect W4 and W5 from the J4 and J5. Note: When replacing the screws, 0.6–0.8 (N.m) 3 Unsolder the antenna connector, C (2 points).
SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS The converted 1st IF signal from the 1st mixer is passed through the monolithic fi lters (FI1, FI2) to suppress unwant- 4-1-1 ANTENNA SWITCHING CIRCUIT ed signals, and then amplifi ed at the 1st IF amplifi er (Q23). The antenna switching circuit toggles the receive line and the transmit line.
4-1-6 SQUELCH CIRCUITS 4-2-2 MODULATION CIRCUIT Noise squelch circuit mutes AF output signals when no RF The modulation circuit modulates the VCO oscillating signal signals are received. By detecting noise components in the with the audio signals from the microphone. demodulated AF signals, the squelch circuit switches the AF mute switch ON and OFF.
4-3 PLL CIRCUITS 4-4 DSC CIRCUITS 4-3-1 VCO CIRCUIT • DECODING A portion of the demodulated AF signals from the FM IF IC The VCO circuit (Q4, Q5, D3, D4) directly generates both of the (IC2, pin 9) are passed through the LPF (Q38) to fi lter DSC 1st LO frequency for receiving (134.35–141.575 MHz) and the signal.
4-6 POWER SUPPLY CIRCUITS Port name Description Line Description NMRXD Input port for the NMEA signal. The voltage from the connected DC power supply. Input port for power switch (VR BOARD; R1). Common 5V converted from the HV line at the L5V regulator Low: When [VOL] is pushed.
Page 12
4-7 PORT ALLOCATIONS (continued) Port name Description Input port for the [DSC] key (LOGIC BOARD; S7). Low: [DSC] key is pushed. Input port for the [PA] key (LOGIC BOARD; S6). Low: [PA] key is pushed. Input por t for the [CH/WX] key (LOGIC CH/WX BOARD;...
SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION M REQUIRED TEST EQUIPMENTS EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE Output voltage : 13.8 V DC Frequency range : 300–3000 Hz DC power supply Audio generator Current capacity : More than 10 A Measuring range : 1–500 mV Measuring range : 1–30 W...
5-2 FREQUENCY ADJUSTMENT ADJUSTMENT MEASUREMENT ADJUSTMENT POINT ADJUSTMENT VALUE CONDITION UNIT OPERATION UNIT ADJUST LOCK 1 • Channel : CH16 (156.800 MHz) MAIN Connect a digital multi- 1.1–2.1 V MAIN Verify VOLTAGE • Receiving meter or oscilloscope to the check point "CP1". 2 •...
5-3 TRANSMIT ADJUSTMENT ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT OPERATION UNIT ADJUST OUTPUT 1 • Channel : CH16 (156.800 MHz) Rear Connect an RF power 23–23.5 W MAIN R112 POWER • Output power : High Panel meter to the antenna •...
5-4 RECEIVE ADJUSTMENT ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT OPERATION UNIT ADJUST SENSITIVITY 1 • Channel : CH16 (156.800 MHz) MAIN Connect a DC volt meter Maximum MAIN L35, L36, L38, • [SQL] : Max. counterclockwise or oscilloscope to the voltage •...
SECTION 6 PARTS LIST 6-1 IC-M422 [LOGIC BOARD] ORDER DESCRIPTION [REPLACEMENT UNITS] LOCATION 7030008121 S.RES ERA3YED 682V 34.5/7.7 ORDER NO. UNIT NAME 7030003860 S.RES ERJ3GE JPW V 33.2/10.5 7030003250 S.RES ERJ3GEYJ 270 V (27 Ω) 0328520101 U M422 #01 FRONT (FRONT+LOGIC+VR+SQL) 71.9/22.7...
Page 24
SECTION 8 SEMICONDUCTOR INFORMATION • TRANSISTOR AND FET’S • DIODES 8 - 1...
Page 25
The combination of this page and the next page shows SECTION 9 BOARD LAYOUTS the unit layout in the same configuration as the actual P.C. Board. 9 - 1...
Page 26
The combination of this page and the previous page shows the unit layout in the same configuration as the actual P.C. Board. 9 - 2...
Page 27
The combination of this page and the next page shows the unit layout in the same configuration as the actual P.C. 9 - 3...
Page 28
The combination of this page and the previous page shows the unit layout in the same configuration as the actual P.C. Board. 9 - 4...
Need help?
Do you have a question about the IC-M422 and is the answer not in the manual?
Questions and answers