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SERVICE
MANUAL
VHF/UHF ALL MODE TRANSCEIVER
i910H
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INTRODUCTION DANGER This service manual describes the latest service information NEVER connect the transceiver to an AC outlet or to a DC for the IC-910H VHF/UHF ALL MODE TRANSCEIVER at the power supply that uses more than 16 V. This will ruin the transceiver. time of publication. DO NOT expose the transceiver to rain, snow or any liquids. VERSION No. VERSION SYMBOL DO NOT reverse the polarities of the power supply when #02 Europe EUR connecting the transceiver. #04 Australia AUS DO NOT apply a
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TABLE OF CONTENTS SECTION 1 SPECIFICATIONS SECTION 2 INSIDE VIEWS 2 - 1 IC-910H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 1 2 - 2 UX-910 (OPTIONAL UNIT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 3 SECTION 3 DISASSEMBLY AND OPTION INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION SECTION 5 ADJUSTMENT PROCEDURES SECTION 6 PARTS
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SECTION 1 SPECIFICATIONS GENERAL • Frequency coverage : (Unit: MHz) 1 Version 144 MHz 430 (440) MHz 1200 MHz* Tx: 144.0–148.0 Tx: 430.0–450.0 Tx: 1240.0–1300.0 U.S.A. 2 3 4 Rx: 136.0–174.0* Rx: 420.0–480.0* Rx: 1240.0–1320.0* Europe 144.0–146.0 430.0–440.0 1240.0–1300.0 Australia 144.0–148.0 430.0–450.0 1240.0–1300.0 Korea 144.0–146.0 430.0–440.0 1260.0–1300.0 1 * Optional UX-910 is installed. 2 * Guaranteed range is 144.0–148.0 MHz. 3 * Guaranteed range is 430.0–450.0 MHz. 4 * Guaranteed rang
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RECEIVER • Receive system : VHF SSB, CW Single conversion superheterodyne FM Double conversion superheterodyne UHF SSB, CW Double conversion superheterodyne FM Triple conversion superheterodyne • Intermediate frequencies : (Unit: MHz) MAIN BAND SUB BAND 1st 2nd 3rd 1st 2nd 3rd SSB 10.8500 —— 10.9500 —— CW 10.8491 —— 10.9491 —— 144 MHz FM 10.8500 0.455 — 10.9500 0.455 — SSB 71.2500 10.8500 — 71.3500 10.9500 — CW 71.2491 10.8491 — 71.3491 10.9491 — 430 (440) MHz FM 71.2500 10.8500 0.455 71.3500
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SECTION 2 INSIDE VIEWS 2-1 IC-910H • MAIN AND PLL UNITS m 2 - 1 * Located under side of the point MAIN unit PLL unit Crystal band pass filter DDS gate array (FI151: FL-128) (IC331: SC-1246A) TX IF amplifier* 430 MHz band VCO circuit (Q1: 3SK131) Crystal band pass filter DDS IC (FI751: FL-129) (IC601: SC-1287) Driver IC (IC1: BU4094BCF) FM IF IC (IC951: TA31136FN) Reference oscillator (X512: CR-452 30.2 MHz) D/A converter DDS gate array (IC1521: M62352GP) (IC131: SC-1246A) AF power amplifier 144
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• PA UNIT 2 - 2 TX/RX switching relay Pre-amplifier (RL700: AE5349) (Q260: 3SK177) Pre-amplifier (Q507: 3SK177) RX balanced mixer (Q220, Q221: 2SC3356) RX balanced mixer (Q511, Q512: 2SK1740) Varistor-C board 145 MHz power amplifier Varistor-B board (Q651, Q652: 2SC5152) 440 MHz power amplifier (Q151, Q152: 2SC3102) TX balanced mixer Q501, Q502: 2SK302 D502: 1SV286 TX balanced mixer* (Q1, Q2: 2SK302) Varistor-A board TX double balanced mixer D190: HSB88WS L190, L191: 617DB-1010 Drive amplifi
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2-2 UX-910 (OPTIONAL UNIT) • TOP VIEW Power supply circuit for AG-1200 Q72: DTC144EU Q73, Q74: 2SC2712 RF pre-amplifier (Q281: NE34018) Power module IC RF amplifier (IC21: M57762-02) (Q271: 2SC5454) TX 1st mixer YGR amplifier (IC131: m PC8163TB) (IC141: m PC1878G) RX 1st mixer (IC241: m PC2721) PLL IC (IC501: TB31242) TX 1st IF amplifier (IC111: m PC2709) 1st LO VCO circuit RX 2nd mixer (Q221: 3SK166) DDS IC TX 2nd mixer (IC661: SC-1246A) (D82: HSB88WS) 2nd LO VCO circuit • BOTTOM VIEW Power s
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SECTION 3 DISASSEMBLY AND OPTION INSTRUCTIONS • Opening the transceiver’s case Follow the case and cover opening procedures shown here when you want to install an optional unit or adjust the internal units, etc. q Remove the 5 screws from the top of the trans- ceiver and 4 screws from the sides, then lift up the top cover. Disconnect the w Turn the transceiver upside down. speaker cable. e Remove 5 screws from the bottom of the trans- ceiver, then lift up the bottom cover. CAUTION: DISCONNECT
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• Opening the PA unit cover q Remove the top cover as shown in the diagram on p. 3- r Slide the PA unit cover as shown below. 1. w Remove 8 screws and grounding plate from the PA unit cover. e Remove fastening tape from the inside power cable. grounding plate • FL-132/FL-133 CW NARROW FILTER q Remove the bottom cover as shown in the diagram on t Install FL-132 or FL-133 to the specified position on the MAIN unit. p. 3-1. • Remove the UX-910 if you have installed it. (p. 3-1) w Disconnect the con
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• UT-102 VOICE SYNTHESIZER UNIT q Remove the bottom cover as shown in the diagram on UT-102 p. 3-1. • Remove the UX-910 if you have installed it. (p. 3-1) w Remove the protective paper attached to the bottom of the UT-102 to expose the adhesive strip. e Plug UT-102 into J1801 on the MAIN unit as shown in the diagram at right. J1801 r Return the bottom cover to its original position. MAIN unit • UT-106 DSP UNIT Installing 2nd DSP unit (rear panel side) RECOMMENDATION: q Remove the top and bottom
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• CR-293 HIGH STABILITY CRYSTAL UNIT y Install the CR-293 and solder the leads. u Return the PLL unit, PLL shield cover and bottom cover q Remove the bottom cover as shown in the diagram on to their original positions. p. 3-1. • Remove the UX-910 if you have installed it. (p. 3-1) w Remove 6 screws from the PLL shield cover, then lift up Original crystal soldering point the PLL shield cover. CR-293 soldering points PLL shield cover e Disconnect the FFC (Flexible Flat Cable) from the DIS- PLAY
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SECTION 4 CIRCUIT DESCRIPTION The filtered signals from the bandpass filter are mixed with 4-1 RECEIVER CIRCUIT 1st LO signals at the mixer circuit (Q511, Q512) to produce Note: [Main]=Main band, [Sub]=Sub band a 1st IF signal (10.85 MHz [Main] or 10.95 MHz [Sub]). The 1st LO signals (125.15 MHz–163.15 MHz) are PLL output 4-1-1 VHF TRANSMIT/RECEIVE SWITCHING frequency, which comes from the VHF VCO circuit (PLL unit; CIRCUIT (PA UNIT) Q191, D191–D194). Received signals from the antenna connector
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4-1-6 10 MHz IF CIRCUIT (MAIN UNIT) 4-1-9 SQUELCH CIRCUIT (MAIN UNIT) The 10 MHz IF signal from the mixer circuit is passed (1) FM mode through a monolithic filter (Fl51 [Main], Fl651 [Sub]) to sup- A squelch circuit cuts out AF signals when no RF signal is press out-of-band signals. The filtered signal is amplified at received or the S-meter signal is lower than the [SQL] con- the IF amplifier (Q51 [Main], Q651 [Sub]). The IF amplifier trol setting level. By detecting noise components in the AF
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4-1-11 NOISE BLANKER CIRCUIT (MAIN UNIT) 4-1-13 S-METER CIRCUIT (MAIN UNIT) The noise blanker circuit detects pulse-type noises, and The S-meter circuit indicates the relative received signal stops IF amplifier operation during detection. strength while receiving and changes depending on the received signal strength. A portion of the 10 MHz IF signal from the bandpass filter (FI51 [Main], FI651 [Sub]) is amplified at the noise amplifier (1) FM mode circuit (Q102, IC101, Q101 [Main], Q702, IC701,
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While in SSB mode, the amplified signals from the buffer 4-2-4 TRANSMIT IF AMPLIFIER CIRCUIT amplifier (Q1651) are then applied to the balanced modula- (MAIN UNIT) tor (IC201). The modulated IF signal from a modulation circuit is applied to the IF amplifier circuit (Q1). The amplified IF signal is then While in AM/FM mode, the amplified signals from the buffer applied to the VHF/UHF transmit circuit (PA unit) via the VHF amplifier (Q1651) are applied to the limiter amplifier /UHF switching circu
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low-pass filter and UHF signal are high-pass filter, and then 4-3 PLL CIRCUITS applied to the VHF and UHF power amplifier circuit sepa- IC-910H contains 2 PLL circuits and 1 local oscillator. The rately. VHF and UHF PLL circuits adopt “Icom’s original I-loop PLL” to obtain very fast lock up times. 4-2-7 POWER AMPLIFIER CIRCUIT (PA UNIT) The power amplifier circuit amplifies the RF signals to the 4-3-1 VHF PLL CIRCUIT (PLL UNIT) specified output power. The VHF PLL circuit generates the 1st LO fre
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The passed signals are then applied to the RF amplifier cir- The amplified signals are passed through the bandpass fil- cuit. ter (FI1) to suppress spurious components, and are ampli- fied at the pre-drive amplifier (Q36, Q38) and power module (IC21) to obtain a stable 10 W of output power. 4-4-2 1200 MHz RF CIRCUIT (for RX) The output signals from the power module (IC21) are Received signals from the transmit/receive switching circuit passed through the duplexer circuit (RL51) and detector cir-
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SECTION 5 ADJUSTMENT PROCEDURES 4-1 PREPARATION BEFORE SARVICING REQUIRED TEST EQUIPMENT EQUIPMENT GREDE AND RANGE EQUIPMENT GREDE AND RENGE Output voltage : 13.8 V DC Frequency range : 300–3000 Hz DC power supply Audio generator Current capacity : 30 A or more Measuring range : 1–500 mV Measuring range : 1–150 W Frequency range : 0.1–1500 MHz Standard signal RF power meter Frequency range : 120–1500 MHz Output level : 0.1 µV–32 mV generator (SSG) (terminated type) Impedance : 50 Ω (–127 to –
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5-2 PLL ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST 30.2 MHz 1 • Display frequency: Any PLL Connect an RF volt- –10 dBm (or more than PLL R570 LEVEL • Receiving meter or spectram –11.5 dBm, when R570 analyzer to check is in maximum posi- point J541. tion.) REFERENCE 1 • Display frequency: Any PLL Connect an RF volt- Maximum level PLL Adjust in FREQUENCY • Receiving meter or spectram (–13 dBm to –7dBm) sequence analyzer to check L551, L
