Icom IC-F21 Service Manual
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Icom IC-F21 Service Manual

Uhf fm transceivers
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SERVICE
MANUAL
UHF FM TRANSCEIVERS

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Summary of Contents for Icom IC-F21

  • Page 1 SERVICE MANUAL UHF FM TRANSCEIVERS...
  • Page 2 INTRODUCTION This service manual describes the latest service information for the IC-F21/IC-F21S at the time of publication. To upgrade quality, all electrical or mechanical parts and internal circuits are subject to change without notice or oblig- ation. DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V.

  • Page 3: Table Of Contents

    TABLE OF CONTENTS SECTION SPECIFICATIONS SECTION INSIDE VIEWS SECTION DISASSEMBLY INSTRUCTIONS SECTION CIRCUIT DESCRIPTION RECEIVER CIRCUITS ........... . .4-1 TRANSMITTER CIRCUITS .
  • Page 4 : 440.000–470.000 MHz • Type of emission : 16K0F3E (at 25 kHz), 8K50F3E (at 12.5 kHz) • Number of channels : 2 ch (IC-F21S), 16 ch (IC-F21) • Power supply requirement : 7.2 V DC (negative ground) • Current drain (approx.) : Transmit at High (4.0 W)
  • Page 5 SECTION 2 INSIDE VIEWS • MAIN UNIT TOP VIEW BOTTOM VIEW Antenna switching circuit D1: 1SV307 D9, D10: MA77 RF amplifier (Q15: 3SK293) Power amplifier (Q1: 2SK2974) (IC2: TA75S01F) Pre-drive (Q2 : 2SK2973) AF amplifier (IC4: TA7368F) YGR amplifier Analog switch Q3: 2SC3585 (IC6: BU4066BCFV) Q4: 2SC5107...

  • Page 6: Disassembly Instructions

    SECTION 3 DISASSEMBLY INSTRUCTIONS • REMOVING THE CHASSIS ¡ Unscrew 1 nut, A, and remove 2 knobs, B, C. ™ Unscrew 2 screws, D. £ Unscrew 2 screws, H, to separate the Jack panel and the Front panel. ¢ Take off the chassis in the direction of the arrow. (Black, 2mm) x 2 ∞...

  • Page 7: Circuit Description

    SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS The signals from the RF circuit are mixed at the 1st mixer (Q16) with a 1st LO signal (393.65–423.65 MHz) coming 4-1-1 ANTENNA SWITCHING CIRCUIT from the VCO circuit to produce a 46.35 MHz 1st IF signal. The antenna switching circuit functions as a low-pass filter while receiving.

  • Page 8: Transmitter Circuits

    The applied AF signals are amplified at the AF power ampli- 4-2-2 MODULATION CIRCUIT fier circuit (IC4, pin 4) to obtain the specified audio level. The The modulation circuit modulates the VCO oscillating signal amplified AF signals output from pin 10 as “AFOUT”signal (RF signal) using the microphone audio signal.

  • Page 9: Pll Circuits

    4-3 PLL CIRCUIT The pulse-type signal is converted into DC voltage (lock voltage) at the loop filter (R40–R42, C74–C77), and then 4-3-1 GENERAL applied to varactor diodes (D5) of the RX-VCO to stabilize A PLL circuit provides stable oscillation of the transmit fre- the oscillated frequency.

  • Page 10: Power Supply Circuits

    4-5 PORT ALLOCATIONS 4-4 POWER SUPPLY CIRCUITS 4-5-1 CPU (IC7) VOLTAGE LINE Port Description LINE DESCRIPTION number name The voltage from the attached battery pack. Input port for RESET signal. The same voltage as the HV line (battery volt- SENC0 age) which is controlled by the power swtich SENC1 Outputs single tone encode signal.
  • Page 11 CPU (IC7)–continued Port Description number name Input port for the battery’s type detec- BDET tion. BATV Input port for battely voltage detection. 4-5-2 OUTPUT EXPANDER IC (IC15) Port Description number name Outputs clock shift control signal for CSFT CPU. RMUT Outputs RX mute control signal.

  • Page 12: Adjustment Procedures

    Measuring range : 10 mV–10 V SYSTEM REQUIREMENTS STARTING SOFTWARE ADJUSTMENT q Connect IC-F21/F21S and PC with the optional OPC-478 • IBM PC compatible computer with an RS -232C serial port (38400 bps or faster) and the JIG cable. w Boot up Windows, and turn the transceiver power ON.
  • Page 13 Screen display exampe CS-F21 ADJ Rev.1.0 File Option COM 1: OPEN Connect Reload (F5) Disp para [A / D] [D / A] : 197 : C5h : 7.73 V BPF T1 : 90 : 5Ah : 1.76 V TEMPS : 190 : BEh : 32.23 ’C BPF T2 : 45 : 2Dh : 0.88 V...
  • Page 14 Connection Standard signal generator to the antenna connector to [MIC] 0.1 V to 32 mV Audio generator (—127 dBm to —17 dBm) CAUTION: DO NOT transmit while an SSG is connected to to an RS-232C port the antenna connector. Personal computer OPC-478 Attenuator...

  • Page 15: Pll Adjustment

    5-2 PLL ADJUSTMENT MEASUREMENT ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITIONS VALUE UNIT LOCATION UNIT ADJUST PLL LOCK • Operating frequency: MAIN Connect a digital multi 1.3 V MAIN VOLTAGE 440.000 MHz meter to check point • Receiving • Transmitting 1.3 V • Operating frequency: 2.8–4.3 V Verify 470.000 MHz...

  • Page 16: Software Adjustment

    5-3 SOFTWARE ADJUSTMENT Select an operation using [ ] / [ ] keys, then set specified value using [ ] / [ ] keys on the connected computer keyboard. MEASUREMENT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION REFERENCE • Operating frequency: Loosely couple a frequnecy 470.0000 MHz FREQUENCY...
  • Page 17 SOFTWARE ADJUSTMENT – continued Select an operation using [ ] / [ ] keys, then set specified value using [ ] / [ ] keys on the connected computer keyboard. MEASUREMENT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION 1 • Operating frequency: Connect a SINAD meter with an Minimum distortion SENSITIVITY...

  • Page 18: Main Unit

    SECTION 6 PARTS LIST [SW-A UNIT] ([F21] only) [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 1590003020 S.TRANSISTOR XP4216-(TX) 1560001050 S.FET 2SK2974 1560001020 S.FET 2SK2973 (MTS101P) 7210003060 VARIABLE TP76N00N-15F-10KA-2251 1530002620 S.TRANSISTOR 2SC3585 R44-T2B 7030003380 S.RESISTOR ERJ3GEYJ 331 V (330 1530003310 S.TRANSISTOR 2SC5107-O (TE85R) 7030003410 S.RESISTOR ERJ3GEYJ 561 V (560 1530003310 S.TRANSISTOR 2SC5107-O (TE85R)
  • Page 19 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 6200009360 S.COIL 0.45-1.4-3TL 11N 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 k ) 6200002860 S.COIL NL 252018T-4R7J 7030003680 S.RESISTOR ERJ3GEYJ 104 V (100 k ) 6200002800 S.COIL ELJFC R68M-F 7030003720 S.RESISTOR ERJ3GEYJ 224 V (220 k ) 6200009360 S.COIL 0.45-1.4-3TL 11N 7030003560 S.RESISTOR...
  • Page 20 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION R152 7030003940 S.RESISTOR ERJ3GEYF 104 V (100 k ) R241 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 k ) R153 7030003940 S.RESISTOR ERJ3GEYF 104 V (100 k ) R242 7030003500 S.RESISTOR ERJ3GEYJ 332 V (3.3 k ) R154 7030003940 S.RESISTOR ERJ3GEYF 104 V (100 k )
  • Page 21 [MAIN UNIT] [MAIN UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 4030006860 S.CERAMIC C1608 JB 1H 102K-T-A C173 4030011600 S.CERAMIC C1608 JB 1C 104KT-N 4030007090 S.CERAMIC C1608 CH 1H 470J-T-A C174 4030007160 S.CERAMIC C1608 CH 1H 181J-T-A 4030011600 S.CERAMIC C1608 JB 1C 104KT-N C175 4030008770 S.CERAMIC C1608 JB 1H 562K-T-A...
  • Page 22 [MAIN UNIT] ORDER DESCRIPTION C261 4030007090 S.CERAMIC C1608 CH 1H 470J-T-A 6910013720 CONNECTOR IMSA-9230B-04Z120-T [F21] only 6910013730 CONNECTOR IMSA-9230B-07Z120-T 6510021900 S.CONNECTOR BM02B-ASRS-TF 6450001680 CONNECTOR HSJ1122-010010 6450001690 CONNECTOR HSJ1456-01-220 7700002160 MICROPHON KUC3523-040245 2230001060 S.SWITCH EVQ-PUL 02K 2230001060 S.SWITCH EVQ-PUL 02K 2230001060 S.SWITCH EVQ-PUL 02K 7030003860 S.JUMPER ERJ3GE JPW V...
  • Page 23 SECTION 7 MECHANICAL PARTS AND DISASSEMBLY [CHASSIS PARTS] [MAIN UNIT] REF. NO. ODER NO. DESCRIPTION QTY. REF. NO. ODER NO. DESCRIPTION QTY. 2510001100 Speaker 036D0601 8510013000 2336 VCO case 8510011180 1923 VCO cover 8210017710 2458 front panel 8510013800 2458 main shield 8930054680 2458 release button 8930055690 Sponge (GT) 8930054690 2458 lens...
  • Page 24 MP21 (C) MP32 (C) MP27 (C) MP8 (C) MP14 (C) MP13 (C) MP29 (C) MP39 (C) MP29 (C) MP12 (C) MP9 (C) MP35 (C)([F21S] only) MP18 (C) MP6 (M) MP19 (C) MP26 (C) MP29 (C) MP7(M) MP33 (C) MP4 (C) MP22 (C) IC-F21S MP6 (C)
  • Page 25 SECTION 8 SEMI-CONDUCTOR INFORMATION • TRANSISTOR AND FET’S 2SA1577 Q 2SB1132 R 2SC3585 R44 2SC4116 GR 2SC4215 O (Symbol: HQ) (Symbol: BARB) (Symbol: R44) (Symbol: LG) (Symbol: QO) 2SC5085 Y 2SC5107 O 2SK880 Y 2SK1829 2SK2973 (Symbol: MCY) (Symbol: MFO) (Symbol: XY) (Symbol: K1) (Symbol: K1)
  • Page 26 SECTION 9 BOARD LAYOUTS 9-1 MAIN UNIT • TOP VIEW R222 R223 R192 C196 R136 R129 R224 R188 R159 R190 C229 R187 R138 C194 to the SW-A/B units C177 C185 R196 C231 C175 R112 R123 R121 R120 R198 C228 TLED IC16 R195 RLED...
  • Page 27 • BOTTOM VIEW C203 C178 R165 R179 C195 R119 C176 C218 R180 R178 R158 C186 R200 R127 R118 R177 C227 R140 R133 R181 R176 C187 C219 R130 R182 R233 R184 R141 R185 R234 C189 C161 R199 C162 C155 R227 C257 R125 R100 C154...

  • Page 28: Sw-A And Sw-B Units

    9-2 SW-A AND SW-B UNITS • TOP VIEW SW-A UNIT SW-B UNIT 9 - 3...
  • Page 29 • BOTTOM VIEW SW-A UNIT to the MAIN unit J1 to the MAIN unit J2 SW-B UNIT B5604C to the MAIN unit J2 9 - 4...

  • Page 30: Parts List

    SECTION 10 BC-146 OPTIONAL DESKTOP CHARGER INFORMATION 10-1 PARTS LIST 10-2 DISASSEMBLY INFORMATION [CHARGE UNIT] REF. NO. ODER NO. DESCRIPTION QTY. 7010007550 RESISTOR ERG3SJ680H 7010007100 RESISTOR PSD1/4V 1 k 6510021470 CONNECTOR HEC0470-01-230 5040001390 LED TLG124A 0910053820 PCB B 5650 8930051340 2338 TERMINAL 8930051340 2338 TERMINAL [CHASSIS UNIT] REF.

  • Page 31: Voltage Diagram

    10-3 VOLTAGE DIAGRAM C : 13.8V C : 7.2V N : 13.8V N : 13.8V R1 68 TLG124A HEC0470-01-230 C : 9.2V N : 13.8V 10-4 BOARD LAYOUT B5650 10 - 2...
  • Page 32 SECTION 11 BLOCK DIAGRAM Q8 DTC144EU XP6501 Q9 XP1214 MAIN UNIT RIPPLE 2SK880 440–470MHz Q10 2SC5085 BUFF LVIN D5 HVU350 CR-671A D3,D4 D1 1SV307 MB15A02PFV1 MA77 RB706F-40 D9,D10 MA77 2SK2974 2SC5107 2SC3585 2SK2973 RX VCO 2SC5107 2SC5107 15.3MHz LOOP TX / RX BUFF BUFF DRIVE...

  • Page 33: Main Unit

    SECTION 12 VOLTAGE DIAGRAM 12-1 MAIN UNIT VCO5V Q12 XP6501 AB 3.3 k 2.7 k 4.9 V 0.001 R47 47 47 P 2SK880 Y 2SC5085 Y C252 0.001 100 P 82 k R220 47 k 2.2 k 11 nH 2SC4215 O 0.5 P 0.001 4.7 H...
  • Page 34 VCO5V 0.001 2SC5085 Y 14 nH 14 nH VCO5V C260 0.001 47 P 4.1 V EXCCL3225U VCO5V 47 P 0.001 0.5 P 0.001 0.82 H 82 k 10 k 47 P 3.7 V 4.7 V 1.8 V 3.7 V 3.3 V 3.5 V 47 P 0.001...
  • Page 35 SECTION 12 VOLTAGE DIAGRAM 12-1 MAIN UNIT VCO5V Q12 XP6501 AB 3.3 k 2.7 k 4.9 V 0.001 R47 47 47 P 2SK880 Y 2SC5085 Y 14 nH C252 VCO5V 14 nH 82 k 0.001 C260 47 k 100 P R220 4.1 V 0.001...

  • Page 36: Sw-A And Sw-B Units

    12-2 SW-A AND SW-B UNITS • SW-A UNIT CP10 CBI0 CP11 CBI1 CP12 CBI2 CP13 CBI3 CBI0 TP76N00N-15F-10KA-2251 VOLOUT VOLIN RX (SQL OPEN) 4.8 V RLED 4.8 V RX (SQL OPEN) 0 V TLED Q1 XP4216 RX (SQL OPEN) 0 V 4.1 V RX (SQL OPEN) 2.1 V LNJ107W5PRW...
  • Page 38 S-13717IZ-C1 1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003, Japan © 2001 Icom Inc.

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