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SERVICE MANUAL VHF AIR BAND TRANSCEIVER iA110...
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This service manual describes the latest service informa- NEVER connect the transceiver to an AC outlet or to a DC tion for the IC-A110 VHF AIR BAND TRANSCEIVER at the power supply that uses more than 16 V. This will ruin the time of publication.
SECTION 3 CIRCUIT DESCRIPTION 3-1 RECEIVER CIRCUITS 3-1-3 1ST MIXER AND 1ST IF CIRCUITS The 1st mixer circuit converts the received signal into a fixed 3-1-1 ANTENNA SWITCHING CIRCUIT frequency of the 1st IF signal with a PLL output frequency. The antenna switching circuit functions as a low-pass filter By changing the PLL frequency, only the desired frequency while receiving.
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3-1-5 AM DETECTOR CIRCUIT (MAIN UNIT) 3-1-7 SQUELCH CIRCUIT The AM detector circuit converts the 2nd IF signal into AF (MAIN AND FRONT UNITS) signals. The squelch circuit cuts out AF signals when receiving no modulated signal. When no voice modulation is included in The amplified 2nd IF signal from the 2nd IF amplifier (Q6) is the signal, the squelch circuit cuts out the AF signal by com- applied to the AM detector circuit (Q7).
3-2 TRANSMITTER CIRCUITS 3-2-3 DRIVE/POWER AMPLIFIER CIRCUITS (MAIN UNIT) 3-2-1 MICROPHONE AMPLIFIER CIRCUIT The amplifier circuit amplifies the VCO oscillating signal to (MAIN UNIT) the output power level. The microphone amplifier circuit amplifies audio signals from the microphone, within +6 dB/octave pre-emphasis The signal from the buffer amplifiers (Q14, Q15) is passed characteristics (300 Hz–3 kHz), to a level needed for the through the TX/RX switch (D11), and is amplified at the pre-...
3-3 PLL CIRCUIT 3-3-3 RX LOOP The generated signal at the RX-VCO (Q59, D65) enters the 3-3-1 GENERAL (MAIN UNIT) PLL IC (IC2, pin 8), and is divided at the programmable A PLL circuit provides stable oscillation of the transmit fre- divider section.
3-5 PORT ALLOCATIONS 3-4 POWER SUPPLY CIRCUITS VOLTAGE LINES (MAIN UNIT) 3-5-1 OUTPUT EXPANDER IC (FRONT unit: IC5) Port LINE DESCRIPTION Description number name The voltage from the external DC power con- nector which is controlled by the power switch Outputs backlight control signals.
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3-5-2 CPU (FRONT unit; IC1) Port Port Description Description number name number name 1, 2, 3, Input port for the microphone hanger Input ports for the key matrix. 5, 8, 12 HANG detection signal. Low: Microphone on hook. RESET Input port for the CPU reset signal. Input port for the PTT switch.
SECTION 4 ADJUSTMENT PROCEDURES 4-1 PREPARATION • Some versions may need the optional CS-A110 and OPC-478, OPC-592 for setting the CLONING SOFTWARE CLONING CABLE adjustment frequency. • All adjustments must be performed on the [Wide] mode. REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE...
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CONNECTION Modulation Attenuator Power supply analyzer 40 dB or 50 dB DC 13.75 V, 10 A RF power meter 50 Ω, 1–50 W Standard signal generator (SSG) 0.1–300 MHz Distortion –127 to –17 dBm (0.1 µV to 32 mV) meter CAUTION! AC millivoltmeter DO NOT transmit...
4-2 PLL ADJUSTMENT ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST • Operating frequency : MAIN Connect a digital 13.5 V MAIN R392 VOLTAGE 118.000 MHz multi-meter to drain • Receiving terminal of Q51. PLL LOCK • Operating frequency : MAIN Connect a digital 0.5 V...
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pin 2 ( MICE) Audio generator pin 4 ( GND) pin 3 ( MIC) pin 5 ( PTT) J6, pin 3 DC power supply Audio input point 13.75 V/10 A R336 Head set modulation adjustment Vdd voltage check point TUNE voltage adjustment TUNE voltage check point R150 Output power adjustment...
4-4 RECEIVER ADJUSTMENT “SQUELCH ADJUSTMENT” must be performed at “SQUELCH ADJUSTMENT MODE”. ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST • Operating frequency : Rear Connect an AC milli- Maximum AF output MAIN L9, L10, SENSITIVITY 118.000 MHz panel voltmeter and dis- level...
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DC power supply 13.75 V/10 A RX sensitivity adjustment 4 - 6...
SECTION 8 BOARD LAYOUTS 8-1 FRONT UNIT The combination of this page and the next page show the unit layout in the same configuration as the actual P.C.Board. ¡TOP VIEW HANG MICE CLON 8 - 1...
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¡BOTTOM VIEW RMUT AFMUT SMUT BEEP FROM MAIN FISW UNIT J5 TMUT UNLK PSWC PLSTB CPU5V MICE PDET PTTS SQLI 8 - 2...
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8-2 MAIN UNIT EXT SP The combination of this page and the next page show the unit layout in the same configuration as the actual ¡TOP VIEW P.C.Board. TO FRONT UNIT J1 8 - 3...
10-2 MAIN UNIT C333 R447 R448 FL-306 Note 1SV307 0.01 1.2k 1SV307 R377 TX: 0 V U : [USA/-1] only 0.5p 0.001 RX: 5.6 V TX: 0.39 V C255 RX: 2.08 V 0.001 RF AGC LS-527 LS-527 TX: 0 V C318 RX: 5.9 V 0.01...
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CHASSIS MOD V (W36) MOD V (ANT) TX: 0 V HK-08S070- HK-08S070- HK-08S070- RX: 5.6 V TX: 0 V TX: 0.39 V 1310 1310 1310 ZBFS5101-PT RX: 2.08 V RX: 1.7 V C358 C342 C165 C362 RF AGC 0.75p 1SV271 0.001 LA-244 LA-244...
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10-2 MAIN UNIT CHASSIS MOD V (W36) MOD V C333 R447 R448 Note FL-306 1SV307 0.01 1.2k 1SV307 R377 (ANT) TX: 0 V U : [USA/-1] only 0.5p 0.001 RX: 5.6 V TX: 0.39 V TX: 0 V HK-08S070- HK-08S070- HK-08S070- 1310 1310...
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290-294 Albert Street, Brunswick, Victoria, 3056, Australia : http://www.icomuk.co.uk Phone : 03 9387 0666 Fax : 03 9387 0022 : http://www.icom.net.au Zac de la Plaine, Rue Brindejonc des Moulinais BP 5804, 31505 Toulouse Cedex, France 6F No. 68, Sec. 1 Cheng-Teh Road, Taipei, Taiwan, R.O.C.
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S-13608HI-CD 6-9-16, Kamihigashi, Hirano-ku Osaka 547-0002, Japan c 2000 Icom Inc.
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