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SERVICE
MANUAL
UHF FM TRANSCEIVERS
S-13717IZ-C1
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003, Japan © 2001 Icom Inc.
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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. Such a connection could cause a fire hazard and/or electric shock. DO NOT expose the transceiver to rain, snow or any liquids. DO NOT reverse
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TABLE OF CONTENTS 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2 4-3 PLL CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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SECTION 1 SPECIFICATIONS Ô Ô GENERAL • Frequency coverage : 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) 1.6 A at Low2 (2.0 W) 1.2 A at Low1 (1.0 W) 0.8 A Receive rated audio 250 mA stand-by 70 mA • Frequency stability : ±0.00025 % • Usable temperature range : –30˚C to +60˚C; –22˚F to +140˚F 1 1
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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) APC Pre-drive (IC2: TA75S01F) (Q2 : 2SK2973) AF amplifier (IC4: TA7368F) YGR amplifier Analog switch Q3: 2SC3585 (IC6: BU4066BCFV) () Q4: 2SC5107 D/A converter TX/RX switch (IC9: M62363FP) (D3, D4: MA77) Crystal filter (FI1: FL-313) FM IF IC VCO circuit (IC3: TA31136FN) PLL reference oscillator 1st mixer (X1: CR-671A 15.3 MHz)
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SECTION 3 DISASSEMBLY INSTRUCTIONS • REMOVING THE CHASSIS Á Unscrew 1 nut, A, and remove 2 knobs, B, C. ª 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 D ° Unplug J6 to separate the front panel and the chassis. Chassis C B J6 (Speaker connector) A Jack panel Front panel (Black, 2mm) x 2 H • REMOVING THE MAIN UNIT Á Remove the sealing rubber. ª Unsolder 2 points, E, and unscrew 2
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SECTION 4 CIRCUIT DESCRIPTION The signals from the RF circuit are mixed at the 1st mixer 4-1 RECEIVER CIRCUITS (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. However, its impedance becomes very high The 1st IF signal is applied to a crystal filter (FI1) to sup- while D9 and D10 are turned ON. Thus transmit signals are pres
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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. are applied to the internal speaker (SP1) as the “SP” signal via the [SP] jack when no plug is connected to the jack. The audio signals change the reactance of a diode (D6) to modulate
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The pulse-type signal is converted into DC voltage (lock 4-3 PLL CIRCUIT 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. The lock voltage is also used for quency and receive 1st LO frequency. The PLL output com- pares the phase of the divided VCO frequency to the refer- the receiver circuit for the bandpass filter center freque
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4-5 PORT ALLOCATIONS 4-4 POWER SUPPLY CIRCUITS 4-5-1 CPU (IC7) VOLTAGE LINE Pin Port Description LINE DESCRIPTION number name HV The voltage from the attached battery pack. 7 RES Input port for RESET signal. The same voltage as the HV line (battery volt- 13 SENC0 VCC age) which is controlled by the power swtich 14 SENC1 Outputs single tone encode signal. ([VOL] control). 19 SENC2 20 SENC3 Common 5 V converted from the VCC line by the +5 regulator circuit (IC10). The output voltage is 23 CENC0 CP
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CPU (IC7)–continued Pin Port Description number name Input port for the battery’s type detec- 61 BDET tion. 62 BATV Input port for battely voltage detection. 4-5-2 OUTPUT EXPANDER IC (IC15) Pin Port Description number name Outputs clock shift control signal for 4 CSFT CPU. 5 RMUT Outputs RX mute control signal. 6 MMUT Outputs TX mute control signal. Outputs low-pass filter cut-off frequen- 7 DUSE cy control signal when DTCS is acti- vated. Outputs T5 regulator control signal. 11 T5C Low: While t
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SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION When you adjust the contents on page 5-5 or 5-6, SOFTWARE ADJUSTMENT, the optional CS-F21 ADJ ADJUSTMENT SOFTWARE (Rev. 1.0 or later), OPC-478 CLONING CABLE and a JIG CABLE (see illustration at page 5-2) are required. REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE Output voltage : 7.2 V DC Frequency range : 300–3000 Hz DC power supply Audio generator Current capacity : 5 A or more Output level : 1–500 mV Measuring ran
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Screen display exampe CS-F21 ADJ Rev.1.0 File Option 2 COM 1: OPEN Connect Reload (F5) Disp para 1 [A / D] [D / A] 4 VIN : 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 3 5 LVIN : 98 : 62h : 1.92 V BPF T3 : 76 : 4Ch : 1.49 V SD : 0 : 00h : 0.00 V T4/POW : 60 : 3Ch : 1.18 V REMOT : 14 : 0Eh : 0.27 V REF : 112 : 70h : 2.20 V BDET : 255 : FFh : 5.00 V DTCS BL. : 141 : 8Dh : 55.29 Dev : 45 : 2Dh : 0.88 V SQL Lev : 150 : 96h : 58.96 6 CH N
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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 FM Attenuator deviation meter 40 dB or 50 dB RF power meter 0.1—10 W/50 ‰ DB9 female plug (incl. level converter circuit) Frequency counter to [SP] SINAD meter JIG cable Speaker (8 ‰) DC power cable connections + DC POWER SUPPLY GND Battery type de
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5-2 PLL ADJUSTMENT MEASUREMENT ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITIONS VALUE UNIT LOCATION UNIT ADJUST PLL LOCK 1 • Operating frequency: MAIN Connect a digital multi 1.3 V MAIN C54 VOLTAGE 440.000 MHz meter to check point • Receiving LV. 2 • Transmitting 1.3 V C68 3 • Operating frequency: 2.8–4.3 V Verify 470.000 MHz • Receiving 4 • Transmitting 2.8–4.3 V RF power meter C54 PLL lock voltage adjustment (RX) C68 PLL lock voltage adjustment (TX) LV PLL lock voltage check point TOP VIEW 5 - 4
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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 1 • Operating frequency: Top Loosely couple a frequnecy 470.0000 MHz FREQUENCY 470.000 MHz panel counter to the antenna connec- [TXF] • High/Low switch : Low tor. • Connect the RF power meter or 50 Ω dummy load to the antenna connector. • Transmitting OUTPUT 1 • Operating frequ
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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 RX 1 • Operating frequency: Top Connect a SINAD meter with an Minimum distortion SENSITIVITY 440.000 MHz panel 8 Ω load to the [SP] jack. level [BPF T1]–[BPF T4] • Channel spacing :Narrow • Connect a standard signal generator to the antenna connector and set as: Frequency : 440.0
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SECTION 6 PARTS LIST [SW-A UNIT] ([F21] only) [MAIN UNIT] REF ORDER REF ORDER DESCRIPTION DESCRIPTION NO. NO. NO. NO. Q1 1590003020 S.TRANSISTOR XP4216-(TX) Q1 1560001050 S.FET 2SK2974 Q2 1560001020 S.FET 2SK2973 (MTS101P) R1 7210003060 VARIABLE TP76N00N-15F-10KA-2251 Q3 1530002620 S.TRANSISTOR 2SC3585 R44-T2B R2 7030003380 S.RESISTOR ERJ3GEYJ 331 V (330 Ω ) Q4 1530003310 S.TRANSISTOR 2SC5107-O (TE85R) R3 7030003410 S.RESISTOR ERJ3GEYJ 561 V (560 Ω ) Q5 1530003310 S.TRANSISTOR 2SC5107-O (TE85R
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[MAIN UNIT] [MAIN UNIT] REF ORDER REF ORDER DESCRIPTION DESCRIPTION NO. NO. NO. NO. L13 6200009360 S.COIL 0.45-1.4-3TL 11N R63 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ ) L14 6200002860 S.COIL NL 252018T-4R7J R64 7030003680 S.RESISTOR ERJ3GEYJ 104 V (100 kΩ ) L15 6200002800 S.COIL ELJFC R68M-F R65 7030003720 S.RESISTOR ERJ3GEYJ 224 V (220 kΩ ) L16 6200009360 S.COIL 0.45-1.4-3TL 11N R66 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ ) L17 6200002860 S.COIL NL 252018T-4R7J R68 7030003380 S.RESI
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[MAIN UNIT] [MAIN UNIT] REF ORDER REF ORDER DESCRIPTION DESCRIPTION NO. NO. NO. NO. R152 7030003940 S.RESISTOR ERJ3GEYF 104 V (100 kΩ ) R241 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ ) R153 7030003940 S.RESISTOR ERJ3GEYF 104 V (100 kΩ ) R242 7030003500 S.RESISTOR ERJ3GEYJ 332 V (3.3 kΩ ) R154 7030003940 S.RESISTOR ERJ3GEYF 104 V (100 kΩ ) R243 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ ) R155 7030003200 S.RESISTOR ERJ3GEYJ 100 V (10 Ω ) R244 7030003240 S.RESISTOR ERJ3GEYJ 220 V (22 Ω ) R156
