Trimmer Adjustment, PLL Lock, Vco, Voltage, Balance | Icom IC-T90A

5-2 TRIMMER ADJUSTMENT

The following adjustment must be performed on the normal mode.

				MEASUREMENT					ADJUSTMENT
ADJUSTMENT		ADJUSTMENT CONDITION		MEASUREMENT				VALUE	POINT
									POINT

				UNIT	LOCATION				UNIT	ADJUST

PLL LOCK	1	• Displayed frequency		VCO	Connect	the	DC	0.4 V–1.0 V		Verify
VOLTAGE			: 30.000 MHz		voltmeter	or	an
		• Mode	: FM		oscilloscope to		the
		• Receiving			checkpoint “CP”.
								7.0 V–11.0 V		Verify
	2	• Displayed frequency						7.0 V–11.0 V		Verify
			: 29.995 MHz
		• Mode	: FM
		• Receiving

	3	• Displayed frequency						0.7 V–2.0 V		verify
			: 150.000 MHz
		• Mode	: WFM
		• Receiving

	4	• Displayed frequency						7.0 V–11.0 V		Verify
			: 169.995 MHz
		• Mode	: WFM
		• Receiving

	5	• Displayed frequency						0.6 V–1.2 V		Verify
			: 550.000 MHz
		• Mode	: WFM
		• Receiving

	6	• Displayed frequency						7.0 V–11.0 V		Verify
			: 629.990 MHz
		• Mode	: FM
		• Receiving

POWER	1	• Displayed frequency		Top	Connect	an	RF	144.000 MHz’s power	RF	L19
BALANCE			: 144.000 MHz	panel	power meter to the
		• Transmitting			antenna connector.

	2	• Displayed frequency						Same value as		L19
			: 148.000 MHz					144.000 MHz’s power
		• Transmitting

	3	• Displayed frequency						440.000 MHz’s power		L16,
			: 440.000 MHz							L456
		• Transmitting

	4	• Displayed frequency						Same value as		L16,
			: 460.000 MHz					440.000 MHz”s		L456
		• Transmitting						power

	5	• Same adjustments as steps 1–4 several times.

5 - 3

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Icom IC-T90A manual Trimmer Adjustment, PLL Lock, Vco, Voltage, Balance

Contents

IC-t90a Introduction Ordering PartsRepair Notes Sample Order Table of Contents Transmitter SpecificationsGeneral Receiver Frequency MHzWFM WFM Inside Views Logic UnitTop view Bottom view Top view Bottom view AF UnitRF Unit Disassembly Instructions Removing the rear panel Removing the AF unit Circuit Description Receiver Circuits RF Circuit 4 1ST Mixer and 1ST if Circuits RF, AF and VCO Units5 2ND if and Demodulator Circuits AF Unit 2ND if and Demodulator Circuit AF Amplifier Circuit AF UnitSquelch Circuitaf and Logic Units Transmitter Circuits PLL Circuits APC Circuit RF UnitGeneral APC Circuit VCO Divider Circuit VCO and RF Units PLL Circuit Power Supply Circuits 2 R3V Switch IC AF Unit IC51Port Allocations Voltage Line CPU Logic Unit IC1 Ctsel DtcsLCD SEG35 Adjustment Procedures Operation on the Adjustment ModeOperation on the Output Power Adjustment Preparation AD-92SMA ConnectionJIG Trimmer Adjustment PLL LockVCO Voltage VCO Unit RF UnitL16 L456 L19 Adjustment Mode Adjustments ReferenceDial Frequency Adjustment Mode Adjustments PH ch 53.900 MHz Transmitting 8V 145 MHz Displayed frequency Connect an amme 45 a Logic Unit R325R365 R326 Ctcss Tracking DetectorCoil AF Unit CP0IC151, pin 12 SD line L151 Displayed frequency Connect a DC volt Maximum voltage Adjustment Adjustment Condition Operation Meter Section Parts List Order Description Coil Eljre 3N9Z-F Ceramic ECJ0EB1H681K Connector AXK6S30445P Ceramic ECJ0EC1H060C Encoder Trimmer Tantalum ECST1EY474R Ceramic ECJ0EC1H2R5B Chassis Parts Mechanical Parts and DisassemblyAccessories Logic Unit RF UnitChassis Parts AF Unit VCO Unit SEMI-CONDUCTOR Information Transistors and FetsDiodes Name Board Layouts TOP ViewMC1 Microphone DUP Logic unit Bottom ViewSP1 SQL PTT RF Unit RF unit EXT.SP EXT.MICREMOTO AF UnitVCO Unit S253S252 Block Diagram Logic Unit Chassis Loop LPF HPF Drive BPF ANT FIL AMP Voltage Diagram 11 1 Logic Unit IC5 11 2 RF Unit 2SK3476 11 3 AF Unit BU4094BCFV URL 32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan