Icom_IC-400Pro_serv.pdf

UHF TRANSCEIVER i400PRO SERVICE MANUAL INTRODUCTION This service manual describes the latest service information for the IC-400PRO UHF TRANSCEIVER at the time of publi- cation. DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. This will ruin the transceiver. DO NOT expose the transceiver to rain, snow or any liquids. DO NOT reverse the polarities of the power supply when con- necting the transceiver. DO NOT apply an RF signal of more than 20 dBm (100 mW) to the antenna connector. This could damage the transceiv- ers front end. ORDERING PARTS Be sure to include the following four points when ordering replacement parts: 1. 10-digit order numbers 2. Component part number and name 3. Equipment model name and unit name 4. Quantity required 1110003490 S.ICTA31136FNIC-400PROMAIN UNIT5 pieces 8810009990 ScrewPH BT M38 ZKIC-400PRO Bottom cover 10 pieces Addresses are provided on the inside back cover for your convenience. REPAIR NOTES 1. Make sure a problem is internal before disassembling the transceiver. 2. DO NOT open the transceiver until the transceiver is disconnected from its power source. 3. DO NOT force any of the variable components.Turn them slowly and smoothly. 4. DO NOT short any circuits or electronic parts. An insu- lated tuning tool MUST be used for all adjustments. 5. DO NOT keep power ON for a long time when the trans- ceiver is defective. 6. DO NOT transmit power into a signal generator or a sweep generator. 7. ALWAYS connect a 40 dB to 50 dB attenuator between the transceiver and a deviation meter or spectrum ana- lyzer when using such test equipment. 8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver. To upgrade quality, any electrical or mechanical parts and internal circuits are subject to change without notice or obligation. IC-400PRO5/25450-500Australia12.5/25 MODELCH. SPACING(kHz)VERSIONPOWER(W)FREQUENCY(MHz) TABLE OF CONTENTS SECTION 1SPECIFICATIONS SECTION 2INSIDE VIEW SECTION 3DISASSEMBLY INSTRUCTIONS SECTION 4CIRCUIT DESCRIPTION 4 - 1RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 1 4 - 2TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 2 4 - 3PLL CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 3 4 - 4POWER SUPPLY CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 4 4 - 5PORT ALLOCATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 4 SECTION 5ADJUSTMENT PROCEDURES 5 - 1PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 1 5 - 2PLL ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 4 5 - 3SOFTWARE ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 5 5 - 4TRIMMER ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 7 SECTION 6PARTS LIST SECTION 7MECHANICAL PARTS AND DISASSEMBLY SECTION 8SEMI-CONDUCTOR INFORMATION SECTION 9BOARD LAYOUTS 9 - 1FRONT UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 1 9 - 2MAIN UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 3 SECTION 10BLOCK DIAGRAM SECTION 11VOLTAGE DIAGRAMS 11 - 1 FRONT UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 1 11 - 2 MAIN UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 - 2 1 - 1 SECTION 1SPECIFICATIONS GENERAL Frequency range: 476.425 MHz477.400 MHzCB 450 MHz500 MHzPrivate Number of conventional channels: 40 channels (Include in 1 bank)CB 88 channels (Include in 28 bank)Private Type of emission: Wide (16K0F3E)(25 kHz; CB) Wide (16K0F3E)/Narrow (8K50F3E)(25 kHz/12.5 kHz; Private) Antenna impedance: 50 nominal Input impedance (Microphone): 600 Output impedance (speaker): 4 Intermediate frequency: 1st IF 46.35 MHz, 2nd IF 450 kHz Operating temperature range: 10 C to +60 C Power supply voltage: 13.8 V DC nominal (Negative ground) Current drain (Approx.): Receive stand-by300 mA Receive max. audio1200 mA Transmit (25 W)7.0 A Transmit (5 W)4.0 A Dimensions: 150(W) 40(H) 117.5(D) mm Weight: 0.8 kg TRANSMITTER Output power: 5 WCB 25 WPrivate Modulation: Variable reactance frequency modulation Maximum permissible deviation: 2.5 kHzNarrow 5.0 kHz Wide Frequency error: 2.5 ppm Spurious emissions: 30 dBm (25 W: 74 dBc, 5 W: 67 dBc) Adjacent channel power: 16 dBm (25 W: 60 dBc, 5 W: 53 dBc) Narrow 22 dBm (25 W: 66 dBc, 5 W: 59 dBc) Wide Audio frequency response: +2 dB to 5 dB of 6 dB/octave From 300 Hz to 2550 Hz Narrow From 300 Hz to 3000 HzWide Audio harmonic distortion: 3 % typical at 40 % deviation FM hum and noise: 34 dB minimum, 40 dB typicalNarrow 40 dB minimum, 46 dB typicalWide Limiting charact of modulator: 70 %100 % of maximum deviation RECEIVER Sensitivity: 0.25 V typical at 12 dB SINAD Audio output power: 4.0 W typical at 10 % distortion with 4 Adjacent channel selectivity: 65 dBNarrow 73 dBWide Spurious response: 75 dB Intermodulation: 70 dB Hum and Noise: 34 dB minimum, 40 dB typicalNarrow 40 dB minimum, 45 dB typicalWide Squelch sensitivity (Threshold): 0.25 V typical All stated specifications are subject to change without notice or obligation. Measurements made in accordance with AS4295-1995, AS/NZS4365-1996. 2 - 1 SECTION 2INSIDE VIEW Antenna switch/ Low-pass filter circuit 1st Mixer* (Q3: 3SK299) 2nd IF filter* (FI2: ALFYM450F=K) D/A converter* (IC6: M62363FP-650C) IF IC (IC1: TA31136FN) 1st IF filter (FI1: FL-335) * Located under side of the point. Final FET module (IC3 : RA30H4452M-21) CPU 5V regulator* (IC10: AN78L05M) 8V regulator (IC9: TA7808F) VCO circuit AF amplifier (IC8: LA4425A) Reference crystal oscillator* (X2: CR-741 15.3 MHz) PLL IC (IC4: MB15A02PFV-1) 3 - 1 SECTION 3DISASSEMBLY INSTRUCTIONS Opening case and removing the front unit qUnscrew 4 screws A, and remove the bottom cover. wDisconnect the flat cable B from J2. eDisconnect the cable C from J7. rUnscrew 2 screws D, and remove the front unit. B C D A J2 J7 yUnscrew 8 screws F. uRemove the filter case G. iUnscrew the screw H. oUnsolder 3 points I from the antenna connector. !0Unsolder 5 points J from IC3. F G H I J !1Lift up the front portion of the main unit and remove it. J1 UT-108 UT-109 UT-110 tUnsolder the point E. E Installation location UT-108DTMF decoder unit UT-109Voice scrambler unit (Non-rolling type) UT-110Voice scrambler unit (Rolling type) 4 - 1 SECTION 4CIRCUIT DESCRIPTION 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. This circuit does not allow transmit signals to enter the receiver circuits. Received signals enter the antenna connector and pass through the low-pass filters (L1L3, C1, C2, C68, C16). The filtered signals are then applied to the RF circuit passed through the 4type antenna switching circuit (D5D7). 4-1-2 RF CIRCUIT (MAIN UNIT) The RF circuit amplifies signals within the range of frequen- cy coverage and filters out-of-band signals. The signals from the antenna switching circuit pass through the two-stage tunable bandpass filters (D8, D4). The filtered signals are amplified at the RF amplifier (Q2) and then enter other two-stage bandpass filters (D9, D10) to suppress unwanted signals. The filtered signals are applied to the 1st mixer circuit (Q3). The tunable bandpass filters (D4, D8D10) employ varactor diodes to tune the center frequency of the RF passband for wide bandwidth receiving and good image response rejec- tion. These diodes are controlled by the CPU (FRONT unit; IC1) via the D/A converter (IC6). The gate control circuit reduces RF amplifier gain and atten- uates RF signal to keep the audio output at a constant level. The receiver gain is determined by the voltage on the “RSSI” line from the FM IF IC (IC1, pin 12). The gate control circuit (Q1) supplies control voltage to the RF amplifier (Q2) and sets the receiver gain. When receiving strong signals, the “RSSI” voltage increases and the gate control voltage decreases. As the gate control voltage is used for the bias voltage of the RF amplifier (Q2), then the RF amplifier gain is decreased. 4-1-3 1ST MIXER AND 1ST IF CIRCUITS (MAIN UNIT) The 1st mixer circuit converts the received signals to a fixed frequency of the 1st IF signal with the PLL output frequency. By changing the PLL frequency, only the desired frequency will pass through a MCF (Monolithic Crystal Filter; FI1) at the next stage of the 1st mixer. The RF signals from the bandpass filter are applied to the 1st mixer circuit (Q3). The applied signals are mixed with the 1st LO signal coming from the RX VCO circuit (Q13) to pro- duce a 46.35 MHz 1st IF signal. The 1st IF signal passes through a MCF (Monolithic Crystal Filter; FI1) to suppress out-of-band signals. The filtered signal is amplified at the 1st IF amplifier (Q4) and applied to the 2nd IF circuit. 4-1-4 2ND IF AND DEMODULATOR CIRCUITS (MAIN UNIT) The 2nd mixer circuit converts the 1st IF signal to a 2nd IF signal. A double-conversion superheterodyne system improves the image rejection ratio and obtains stable receiv- er gain. The 1st IF signal from the 1st IF amplifier (Q4) is applied to the 2nd mixer section of the FM IF IC (IC1, pin 16) and is then mixed with the 2nd LO signal for conversion to a 450 kHz 2nd IF signal. IC1 contains the 2nd mixer, limiter amplifier, quadrature detector, active filter and noise amplifier circuits, etc. A tripled frequency from the PLL reference oscillator is used for the 2nd LO signal (45.9 MHz). The 2nd IF signal from the 2nd mixer (IC1, pin 3) passes through a ceramic filter (FI2) to remove unwanted hetero- dyned frequencies. It is then amplified at the limiter amplifi- er section (IC1, pin 5) and applied to the quadrature detec- tor section (IC1, pins 10, 11 and X1) to demodulate the 2nd IF signal into AF signals. The AF signals are output from pin 9 (IC1) and are then applied to the AF amplifier circuit. FI2 2nd IF filter 450 kHz Noise detector Q34 Limiter amp. FM detector Active filter AF signals (DET signal) SQLIN signal from the D/A converter IC (IC6, pin 2) 5V X1 Discriminator RSSI Mixer X2 15.3 MHz 45.9 MHz 1st IF from the IF amplifier (Q4) RSSI signal to the CPU NOIS signal to the CPU 875 BPF 32 2 PLL IC (IC4) 1 3 16121311109 IC1 TA31136FN 2ND IF AND DEMODULATOR CIRCUIT 4 - 2 4-1-5 AF AMPLIFIER CIRCUIT (MAIN UNIT) The AF amplifier circuit amplifies the demodulated AF sig- nals to drive a speaker. The AF signals from the FM IF IC (IC1, pin 9) are applied to the active filter circuit (IC16). The active filter circuit (high- pass filter) removes CTCSS or DTCS signals. The filtered AF signals are output from pin 14 (IC16) and are applied to the de-emphasis circuit (R117, C378) with fre- quency characteristics of 6 dB/octave, and then passed through the analog switch (IC14, pins 13) and low-pass fil- ter (IC5). The filtered signal is applied to the electronic vol- ume controller (IC6, pin 9). The output AF signals from the electronic volume controller (IC6, pin 10) are passed through the analog switch (IC14 pins 911) and are applied to the AF amplifier (IC15) and AF power amplifier (IC8) to drive the speaker. 4-1-6 RECEIVER MUTE CIRCUITS (MAIN AND FRONT UNITS) NOISE SQUELCH 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. Some noise components in the AF signals from the FM IF IC (IC1, pin 9) are passed through the level controller (IC6, pins 1, 2). The level controlled signals are applied to the active fil- ter section in the FM IF IC (IC1, pin 8). Noise components about 10 kHz are amplified and output from pin 7. The filtered signals are converted to the pulse-type signals at the noise detector section and output from pin 13 (NOIS). The NOIS signal from the FM IF IC is applied to the CPU (FRONT unit; IC1, pin 53). The CPU then analyzes the noise condition and controls the AF mute signal via “AFON” line (D44, D45) to the AF mute circuit (Q35, Q36, D29, D30). CTCSS AND DTCS The tone squelch circuit detects AF signals and opens the squelch only when receiving a signal containing a matching subaudible tone (CTCSS or DTCS). When tone squelch is in use, and a signal with a mismatched or no subaudible tone is received, the tone squelch circuit mutes the AF signals even when noise squelch is open. A portion of the AF signals from the FM IF IC (IC1, pin 9) passes through the low-pass filter (IC16) to remove AF (voice) signals and is applied to the CTCSS or DTCS decoder inside the CPU (FRONT unit; IC1, pin 60) via the “CDEC” line to control the AF mute switch. 4-2 TRANSMITTER CIRCUITS 4-2-1 MICROPHONE AMPLIFIER CIRCUIT (MAIN AND FRONT UNITS) The microphone amplifier circuit amplifies audio signals within +6 dB/octave pre-emphasis characteristics from the microphone to a level needed for the modulation circuit. The AF signals (MIC) from the MIC jack (FRONT unit; J1) are amplified at the AF amplifier (FRONT unit; IC5) and applied to the MAIN unit via J2 (pin 28). The AF signal are applied to the limiter amplifier (IC5, pin 5). The entered signals are pre-emphasized with +6dB/octave at a limiter amplifier, then passed through the analog switch (IC14, pins 24) and splatter filter (IC5, pins 2, 1). The out- put signals from the splatter filter are applied to the level controller (IC6, pin 9). The deviation level controlled signals are then applied to the modulation circuit (D18) as the “MOD” signal after being passed through the analog switch (IC14, pins 9, 8). 4-2-2 MODULATION CIRCUIT (MAIN AND FRONT UNITS The modulation circuit modulates the VCO oscillating signal (RF signal) using the microphone audio signals. The AF signals from the analog switch (IC14, pin 8) change the reactance of varactor diode (D18) to modulate the oscil- lated signal at the TX VCO circuit (Q14, D17). The modulat- ed VCO signal is amplified at the buffer amplifiers (Q11, Q10) and is then applied to the drive amplifier