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16 V. This will ruin the time of publication. transceiver. 2 versions of the IC-M401EURO have been designed. This service manual covers each version. DO NOT expose the transceiver to rain, snow or any liquids.
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SECTION 1 SPECIFICATIONS ‘ ‘ GENERAL • Frequency coverage : 156.025–157.425 MHz (Tx) 156.300–162.025 MHz (Rx) • Mode : 16K0G3E (FM) • Power supply requirement : 13.8 V DC (negative ground) • Usable temperature range : –20˚C to +60˚C; –4˚F to +140˚F •...
SECTION 3 DISASSEMBLY INSTRUCTIONS • • REMOVING THE CASE REMOVING THE MAIN UNIT ¡ Unscrew 6 screws, A. ¡ Remove the shield cover. Note: When replacing the screw, 10–12 kg of torque MUST ™ Unsolder DC cable (4 points) and antenna connector, B (2 points), as shown below.
SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS The signals from the RF circuit are mixed with the VCO sig- nals at the 1st mixer circuit (Q1) to produce a 21.7 MHz 1st 4-1-1 ANTENNA SWITCHING CIRCUIT IF signal. (MAIN UNIT) The antenna switching circuit functions as a low-pass filter The 1st IF signal is applied to two crystal filters (FI1, FI2) to while receiving and as resonator circuit while transmitting.
4-1-5 AF AMPLIFIER CIRCUIT The amplified signals are passed through the MIX circuit (IC10A, pins 2, 1) to do amplitude limiting. and are then (MAIN AND FRONT UNITS) applied to the splatter filter (IC10B, pin 5) to suppress The AF amplifier circuit amplifies the detected signals to unwanted 3 kHz or higher signals.
4-3 PLL CIRCUITS 4-3-2 TX AND RX LOOP (MAIN UNIT) The generated signal at the VCO (Q4, Q5, Q6, D1–D4) 4-3-1 GENERAL enters the PLL IC (IC2, pin 2) and is divided at the pro- The PLL circuit provides stable oscillation of the transmit fre- grammable divider section and is then applied to the phase quency and receive 1st LO frequency.
4-4 ATIS AND DSC CIRCUITS 4-6 POWER SUPPLY CIRCUITS 4-4-1 ATIS ENCODE CIRCUIT ([HOL], [FRG] ONLY) VOLTAGE LINES (LOGIC BOARD AND MAIN UNIT) LINE DESCRIPTION The FSK signal of ATIS created at CPU (IC1) is passed The voltage from the connected DC power sup- through the ladder type D/A convertor (R55–R73) to convert ply.
4-7 PORT ALLOCATIONS 4-7-1 CPU (LOGIC BOARD; IC1) Port Port Description Description number name number name Outputs control signal for the LCD Input port for the HM-132 functions. contrast. 2.02 V: [UP] is pushed. KEYM CONT1 3.00 V: [DN]] is pushed. CONT2 CONT1 CONTRAST...
SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION REQUIRED TEST EQUIPMENT 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 : 10 A or more Measuring range : 1–500 mV Measuring range...
5-2 PLL ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST LOCK • Operating channel : ch16 MAIN Connect a digital 1.8 V Verify VOLTAGE • Receiving multi-meter or oscil- loscope check point CP1. • Operating channel : ch16 1.6 V •...
5-3 TRANSMITTER ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST OUTPUT • Operating channel : ch16 Rear Connect 22.5 W MAIN POWER • Output power : High Panel power meter to the • Transmitting antenna connector. FREQUENCY •...
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Output power adjustment R138 Frequency deviation adjustment Squelch level adjustment Squelch level check point Audio generator [PTT] 300 Hz to 3 kHz AC millivoltmeter 2 200 mV 5 - 4...
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SECTION 8 SEMI-CONDUCTOR INFORMATION • • TRANSISTOR AND FET’S DIODES 1SS355 1SS375 DA204 U DSA3A1 2SA1576 R 2SA1588 GR 2SB1132 R 2SB1202 S 2SC2714 Y HSM88ASR (Symbol: BAR) (Symbol: B1202) (Symbol: QY) (Symbol: A) (Symbol: FH) (Symbol: K) (Symbol: C3) (Symbol: FR) (Symbol: ZG) green...
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SECTION 9 BOARD LAYOUTS 9-1 VR-A BOARD 9-3 HM-132 to Main unit J5 • TOP VIEW B-5585B 9-2 VR-B BOARD • BOTTOM VIEW to Main unit J5 B-5586B 9 - 1...
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9-4 LOGIC BOARD • TOP VIEW B5679A ICOM to Front unit SP1 to Front unit SP1 From HM-132 to DSC terminal DS-100 to Main unit J6 9 - 2...
SECTION 11 VOLTAGE DIAGRAM 11-1 LOGIC BOARD R20 18 k DIM3 TTR5341 2SB1132 R CH16 CH16 SEG26 10 k SEG27 12 k 39 k SEG12 100 k 100 k 100 k 100 k 18 k SEG13 FY1101 F-TR DIM2 BAND EXTENTION 2SC4116 BL 2SC4116 BL SEG14...
11-2 MAIN UNIT C299 580mVp-p at 3kHz DEV IC13 RX: 3.07 V R158 100 NJM2125F R210 10 k CDBCA450CX24 0.01 C226 L28 82 nH R215 C252 0.10 H 470 P R155 12 k 1.5 k 0.001 0.22 0.001 R25 100 100 P R214 33 k...
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11-3 HM-132 470 P 12 k CHASSIS UNIT W1 MICG MICG to MAIN unit J4 PTTG 6.8 k KEYM to LOGIC board J3 15 k UP_ON 2.0V DN_ON 3.0V 16/9_ON 3.8V 33 k 16/9...