Icom IC-M2A Service Manual

for the IC-M2A/IC-M21 VHF MARINE TRANSCEIVER at the time of publication. NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 10 V. This will ruin the transceiver. DO NOT expose the transceiver to rain, snow or any ...

SECTION 1 SPECIFICATIONS SECTION 2 INSIDE VIEWS SECTION 3 DISASSEMBLY INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1 4-2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

All stated specifications are subject to change without notice or obligation. Frequencycoverage Mode Power supply requirement Usable temperature Frequency stability at 5 W at 3 W at 1 W at 0.5 W at maximum audio at stand-by Antenna impedance Dimensions (Projections not included) Weight (with antenna and BP-224) RF output power (at 7.2 V DC) Modulation ...

* Low power only NOTE: Channels 3, 21, 23, 61, 64, 81, 82 and 83 CANNOT be used by the general public in USA waters. CAN 21A 22A 23 24 25 26 27 28 60 61A 62A 64 64A 65A 66A* 67 68 69 70 71 72 CAN 73 74 77* 78A 79A 80A 81A 82A 83 83A 84 85 86 87 88 21b 25b 28b 83b CAN 01 02 03 04A 05A 06 07A 08 09 10 11 12 13* 14 15* 16 17* 18A 19A 20* 21 ‘ VHF MARINE ...

* Low power only ‘ VHF MARINE CHANNEL LIST (For IC-M21) USA 01A 03A 05A 06 07A 08 09 10 11 12 13* 14 15* 16 17* 18A 19A 20 20A 21A INT 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15* 16 17 18 19 20 21 Transmit 156.050 156.050 156.100 156.150 156.150 156.200 156.250 156.250 156.300 156.350 156.350 156.400 156.450 156.500 156.550 156.600 156.650 156.700 ...

SECTION 2 INSIDE VIEWS • MAIN UNIT TOP VIEW BOTTOM VIEW Antenna switching circuit (D52: 1SV307) Power amplifier (Q54: 2SK2974) APC (IC50: NJM2125F) IF amplifier (Q151: 2SC2714 Y) TX/RX switch (D50, D51: MA77) Antenna switching circuit D90: 1SV307 D91: 1SS375 ( ) 1st mixer (Q150: 3SK272) VCO circuit IF DETECTOR IC (IC170: TA31136FN) PLL IC (IC1: µ ...

SECTION 3 DISASSEMBLY INSTRUCTIONS • Removing the Rear panel • Removing the Chassis unit Rear panel A B C C Rubber Front panel Front panel Chassis unit VR unit E G D F (Speaker connector) ¡ Unscrew 1 screw, A (2 x 10 mm), and remove 1 washer, B. ™Unscrew 3 screws, C (2 x 8 mm). £ Remove the rear pan ...

4-1 RECEIVER CIRCUITS 4-1-1 ANTENNA SWITCHING CIRCUIT (MAIN UNIT) The antenna switching circuit functions as a low-pass filter while receiving and as resonator circuit while transmitting. The circuit does not allow transmit signals to enter receiver circuits. Received signals from the antenna connector pass through the low-pass fileter (L80–L82, C80� ...

4-1-5 SQUELCH CIRCUIT (MAIN UNIT) The noise squelch circuit cuts out AF signals when no RF signals are received. By detecting noise components in the AF signals, the squelch circuit switches the AF mute switch. A portion of the AF signals divided by C175 from the FM IF IC (IC170, pin 9) are applied to the D/A convertor (IC190, pin 16) to adjust amplitu ...