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EFJohnson 764X, 761X service manual Vhf Adjustments Cont’D, 4VHF Adjustment Points

Models: 761X 764X

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VHF ADJUSTMENTS (CONT’D)

ADJUSTMENT PROCEDURE

VHF ADJUSTMENTS (CONT’D)

L14

PLL lock voltage adjustment

CP1

PLL lock voltage check point

Figure 6-4 VHF Adjustment Points

4.Press (Enter) again to select the second adjust chan- nel. Key the transmitter and adjust for the displayed frequency. Unkey the transmitter and press (Enter) again to exit this function.

6.4.2 OUTPUT POWER ADJUST

1.Select the high power channel in the middle of the band (Test Ch. 3 - 160.050 MHz). Connect a power meter to the antenna jack.

2.Scroll to “Power (Hi)” on the screen and key the transmitter using the test cable switch. Use the com-

puter adjust keys to set the following power. Unkey the transmitter. Repeat for the Low2 (Test Ch. 4) and Low1 (Test Ch. 5) power levels.

High Power = 45 watts (Test Ch. 3)

Low2 Power = 25 watts (Test Ch. 4)

Low1 Power = 4.5 watts (Test Ch. 5)

6.4.3 FM DEVIATION ADJUST

1.Connect an audio generator to the microphone audio input of the test cable (pin 5 shown in Figure 6-3). Set the generator output for 1 kHz at 40 mV rms.

	November 1998
6-5	Part No. 001-7600-001

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EFJohnson 764X, 761X service manual Vhf Adjustments Cont’D, 4VHF Adjustment Points

Contents

761x VHF 764x UHF Conventional Mobile VHF 146-174MHz 45 Watts Part No.UHF 400-430, 450-470, 490-512MHz 35 Watts Part No.VHF 146-174MHz 45 Watts UHF 400-430, 450-470, 470-490,or 490-512MHz35 Watts 761x VHF 764x UHF CONVENTIONAL FM TWO-WAYRADIOTABLE OF CONTENTS 2 INSTALLATION AND DISASSEMBLY1 GENERAL INFORMATION 3 OPERATIONTABLE OF CONTENTS CONT’D 6 ADJUSTMENT PROCEDURE7 PARTS LIST 5A VHF 7610 CIRCUIT DESCRIPTION8SCHEMATIC DIAGRAMS AND COMPONENT LAYOUTS LIST OF TABLESLIST OF FIGURES TABLE OF CONTENTS CONT’D1.3 PRODUCT WARRANTY 1.6 ACCESSORIES1.7 FACTORY CUSTOMER SERVICE SECTION 1 GENERAL INFORMATIONTable 1-175xx Accessories 1.8 FACTORY RETURNSAccessory Toll-Free:8001.9 REPLACEMENT PARTS 1.10 INTERNET HOME PAGEThis page intentionally left blank NovemberPart No. 7610 VHF AND 7640 UHF MOBILE SPECIFICATIONS GENERALNOTES NovemberSECTION 2 INSTALLATION AND DISASSEMBLY Figure 2-1Installation Components2.2 TRANSCEIVER INSTALLATION 2.1 GENERALFigure 2-2Mounting Bracket Installation 2.2.2 INSTALLING MOUNTING BRACKET2.2.3 INSTALLING MICROPHONE HANGER 2.3 POWER CABLE INSTALLATIONChanging 20-AmperePower Cable Fuses 2.4 USING AN EXTERNAL SPEAKER2.5 ACCESSORY CABLE INSTALLATION DB-9Pin2.6 TRANSCEIVER DISASSEMBLY Figure 2-5PC Board ScrewsFigure 2-4Cover and Front Panel Removal Figure 2-6Removing PC Board2.7 2-TONE/5-TONEMODULE INSTALLATION Figure 2-7 2/5-ToneModule InstallationSetting 5-ToneDeviation 25 kHz Channel Spacing - ±3.5 kHz 3.1 FEATURES SECTION 3 OPERATIONFigure 3-17600 Front Panel 3.2 CONTROLS AND DISPLAY 3.3 BASIC OPERATIONDirect Selection - The F1-F4and 3.4 RECEIVING AND PLACING CALLS 3.5 PROGRAMMABLE FUNCTIONS Table 3-1Option Key Programmable FunctionsFunction Key Label1.Press the TONE key and “TON--x”is displayed 3.6 CHANNEL SCAN 3.6.3 PRIORITY CHANNEL SAMPLING NovemberPart No. Figure 4-1Programming Setup SECTIONPROGRAMMING 4.1 GENERAL4.2STARTING THE PROGRAM 4.3 SPECIAL KEYS AND FUNCTIONS4.4 MENU FLOW Current - Prints the currently displayed data 4.4.7 SETUP MENU ParameterDescription Bank SelectParameter Auto Reset ParameterRF PWR LockoutDescription ParameterLabel Description LabelParameter Table 4-3DTMF Autodial Screen Description ParameterParameter Table 4-4Continuous Tone Screen Description Table 4-5Scan Function Screen DescriptionNovember Part No.Table 4-6 2-ToneCode Channel Screen Description DescriptionParameter ParameterParameter BeepTable 4-7Common Screen Description Table 4-7Common Screen Description Continued Table 4-8Expert Screen DescriptionParameter Table 4-8Expert Screen Description Continued 4.5 UNIQUE PMR EUROPEAN SCREENSDescription PROGRAMMING Figure 4-2Memory Channel Screen PMR Models November4-17 Part No.This page intentionally left blank NovemberPart No. 4-18SECTION 5A VHF 7610 CIRCUIT DESCRIPTION 5.1 VHF RECEIVER CIRCUITFigure 5-1Second IF System IC3 VHF 5.2 VHF TRANSMITTER CIRCUIT Figure 5-3PLL Circuit VHF 5.2.5 APC CIRCUIT5.3 VHF PLL CIRCUIT 5.3.1 PLL CIRCUIT5.4 VHF IC PIN DESCRIPTIONS LineDescription PortPort SECTION 5B UHF 7640 CIRCUIT DESCRIPTION 5.5 UHF RECEIVER CIRCUITFigure 5-4Second IF System IC1 UHF 5.6 UHF TRANSMITTER CIRCUIT Figure 5-6PLL Circuit UHF 5.7 UHF PLL CIRCUIT5.7.3 UHF POWER SUPPLY 5.7.2 VCO CIRCUIT5.7.4 UHF CPU IC1 PORT ALLOCATION November5.7.5 UHF I/O EXPANDER IC12 MAIN UNIT 5.7.6 UHF PORT EXPANDER IC13 MAIN UNITNovember Part No.SECTION 6 ADJUSTMENT PROCEDURE Test SetupFigure 6.1 GENERALFigure 6-3Test Cable Schematic Figure 6-2Screen Display Example6.1.2 TEST CHANNELS 6.1.3 TEST CABLETable 6-1VHF Test Frequencies Table 6-2UHF Test FrequenciesADJUST /X /Y VHF ADJUSTMENTS VHF ADJUSTMENTS6.2 PRELIMINARY SETUP 6.3 PLL ADJUSTMENT VHF MODELSVHF ADJUSTMENTS CONT’D Figure 6-4VHF Adjustment Points6.5 RECEIVER ADJUSTMENTS VHF MODELS VHF ADJUSTMENTS CONT’DFigure 6-5Beep Tone Level Adjustment VHF ADJUSTMENTS CONT’DUHF ADJUSTMENTS 6.6 PLL ADJUSTMENT UHF MODELS6.7TRANSMITTER ADJUSTMENTS UHF MODELS UHF ADJUSTMENTS CONT’D Figure 6-6UHF Adjustment Points6.7.4 DTCS WAVEFORM ADJUST 6.8 RECEIVER ADJUSTMENTS UHF MODELS UHF ADJUSTMENTS CONT’DSECTION 7 PARTS LIST æçìíýõ9+ôý0$,1ý81,77610 VHF Main Unit HVFULSWLRQ76105 VHF Main Unit HVFULSWLRQHVFULSWLRQ November7610 VHF Main Unit HVFULSWLRQHVFULSWLRQ November7610 VHF Main Unit HVFULSWLRQHVFULSWLRQ November Part No.7610 VHF Main Unit HVFULSWLRQHVFULSWLRQ November7610 VHF Main Unit HVFULSWLRQHVFULSWLRQ November7610 VHF Main Unit HVFULSWLRQHVFULSWLRQ Novemberæçéíýõ8+ôý0$,1ý81,7 7640 UHF Main Unit7610 VHF Main Unit HVFULSWLRQ7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November5HIý1Rï 7640 UHF Main UnitHVFULSWLRQ HVFULSWLRQ7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November Part No.7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November7640 UHF Main Unit HVFULSWLRQHVFULSWLRQ November Part No.7640 UHF Main Unit HVFULSWLRQNovember 7-175217ý81,7 õ9+ý$1ý8+ý02/6ô Front Unit All Models7640 UHF Main Unit 5HIý1RïFront Unit All Models HVFULSWLRQHVFULSWLRQ Novemberæçìíýõ9+ôý&+$66,6ý3$576 æçéíýõ8+ôý&+$66,6ý3$576Chassis Parts Front Unit All ModelsVHF 7610 EXPLODED VIEW 7-21November Part No.←FOLDOUT VHF Exploded View UHF 7640 EXPLODED VIEWVHF 7610 BLOCK DIAGRAM MAIN UNITFRONT UNIT VHF 7610 Transistor Basing Diagrams VHF 7610 Diode Basing DiagramsFOLDOUT → VHF 7610 MAIN BOARD BOTTOM VIEWVHF 7610 MAIN BOARD TOP VIEW NovemberPart No. VHF 7610 MAIN BOARD SCHEMATIC VHF MAIN UNITUHF 7640 BLOCK DIAGRAM NovemberPart No. FOLDOUT → UHF 7640 MAIN BOARD BOTTOM VIEWNovember UHF 7640 MAIN BOARD TOP VIEW J4 T o O p tion al Un itJ2 T o S p kr J5 T o O p t Ca bleUHF 7640 MAIN BOARD SCHEMATIC VHF/UHF FRONT UNIT BOARD TOP VIEW VHF/UHF FRONT UNIT BOARD BOTTOM VIEWVHF/UHF FRONT UNIT SCHEMATIC FRONT UNITUHF 7640 Transistor Basing Diagrams UHF 7640 Diode Basing DiagramsTRANSISTORS AND FETS • DIODES