Manuals / EFJohnson / Home Audio / Speaker

EFJohnson 761X, 764X service manual kHz Channel Spacing - ±3.5 kHz

Models: 761X 764X

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INSTALLATION AND DISASSEMBLY

1.Monitor the transmit signal with a communications monitor. Set it for HPF = Off, LPF = 20 kHz, De- emphasis = Off, and Level = (P-P)/2.

2.Select a channel near the center of the band and turn a long tone on (see preceding “NOTE”) by pressing the appropriate front panel key.

3.Adjust potentiometer R18 (DEV) on the module for the following deviation:

25 kHz Channel Spacing - ±3.5 kHz

20 kHz Channel Spacing - ±2.8 kHz

12.5 kHz Channel Spacing - ±1.7 kHz

4.Check channels on each end of the operating band to make sure deviation is within the following limits. If not, repeat preceding adjustment.

25 kHz Channel Spacing - ±3.0 to 5.0 kHz 20 kHz Channel Spacing - ± 2.4 to 4.0 kHz 12.5 kHz Channel Spacing - ±1.5 to 2.5 kHz

NOTE: It is recommended that scanning not be used with these options because in may cause part or all of the tone burst to be missed.

November 1998
Part No. 001-7600-001	2-6

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EFJohnson 761X, 764X service manual kHz Channel Spacing - ±3.5 kHz

Contents

VHF 146-174MHz 45 Watts Part No. 761x VHF 764x UHF Conventional MobileUHF 400-430, 450-470, 490-512MHz 35 Watts Part No.UHF 400-430, 450-470, 470-490,or 490-512MHz VHF 146-174MHz 45 Watts35 Watts 761x VHF 764x UHF CONVENTIONAL FM TWO-WAYRADIO2 INSTALLATION AND DISASSEMBLY TABLE OF CONTENTS1 GENERAL INFORMATION 3 OPERATION6 ADJUSTMENT PROCEDURE TABLE OF CONTENTS CONT’D7 PARTS LIST 5A VHF 7610 CIRCUIT DESCRIPTIONLIST OF TABLES 8SCHEMATIC DIAGRAMS AND COMPONENT LAYOUTSLIST OF FIGURES TABLE OF CONTENTS CONT’D1.6 ACCESSORIES 1.3 PRODUCT WARRANTY1.7 FACTORY CUSTOMER SERVICE SECTION 1 GENERAL INFORMATION1.8 FACTORY RETURNS Table 1-175xx AccessoriesAccessory Toll-Free:8001.10 INTERNET HOME PAGE 1.9 REPLACEMENT PARTSPart No. This page intentionally left blankNovember GENERAL 7610 VHF AND 7640 UHF MOBILE SPECIFICATIONSNovember NOTESFigure 2-1Installation Components SECTION 2 INSTALLATION AND DISASSEMBLY2.2 TRANSCEIVER INSTALLATION 2.1 GENERAL2.2.2 INSTALLING MOUNTING BRACKET Figure 2-2Mounting Bracket Installation2.2.3 INSTALLING MICROPHONE HANGER 2.3 POWER CABLE INSTALLATION2.4 USING AN EXTERNAL SPEAKER Changing 20-AmperePower Cable Fuses2.5 ACCESSORY CABLE INSTALLATION DB-9PinFigure 2-5PC Board Screws 2.6 TRANSCEIVER DISASSEMBLYFigure 2-4Cover and Front Panel Removal Figure 2-6Removing PC BoardSetting 5-ToneDeviation 2.7 2-TONE/5-TONEMODULE INSTALLATIONFigure 2-7 2/5-ToneModule Installation 25 kHz Channel Spacing - ±3.5 kHz Figure 3-17600 Front Panel 3.1 FEATURESSECTION 3 OPERATION 3.3 BASIC OPERATION 3.2 CONTROLS AND DISPLAYDirect Selection - The F1-F4and 3.4 RECEIVING AND PLACING CALLS Table 3-1Option Key Programmable Functions 3.5 PROGRAMMABLE FUNCTIONSFunction Key Label1.Press the TONE key and “TON--x”is displayed 3.6 CHANNEL SCAN Part No. 3.6.3 PRIORITY CHANNEL SAMPLINGNovember SECTION Figure 4-1Programming SetupPROGRAMMING 4.1 GENERAL4.4 MENU FLOW 4.2STARTING THE PROGRAM4.3 SPECIAL KEYS AND FUNCTIONS Current - Prints the currently displayed data Parameter 4.4.7 SETUP MENUDescription Bank SelectParameter Parameter Auto ResetRF PWR LockoutLabel DescriptionParameter Parameter DescriptionLabel Parameter Table 4-3DTMF Autodial Screen DescriptionParameter Table 4-5Scan Function Screen Description Table 4-4Continuous Tone Screen DescriptionNovember Part No.Description Table 4-6 2-ToneCode Channel Screen DescriptionParameter ParameterBeep ParameterTable 4-7Common Screen Description Parameter Table 4-7Common Screen Description ContinuedTable 4-8Expert Screen Description Description Table 4-8Expert Screen Description Continued4.5 UNIQUE PMR EUROPEAN SCREENS PROGRAMMING November Figure 4-2Memory Channel Screen PMR Models4-17 Part No.November This page intentionally left blankPart No. 4-185.1 VHF RECEIVER CIRCUIT SECTION 5A VHF 7610 CIRCUIT DESCRIPTIONFigure 5-1Second IF System IC3 VHF 5.2 VHF TRANSMITTER CIRCUIT 5.2.5 APC CIRCUIT Figure 5-3PLL Circuit VHF5.3 VHF PLL CIRCUIT 5.3.1 PLL CIRCUITLine 5.4 VHF IC PIN DESCRIPTIONSDescription PortPort 5.5 UHF RECEIVER CIRCUIT SECTION 5B UHF 7640 CIRCUIT DESCRIPTIONFigure 5-4Second IF System IC1 UHF 5.6 UHF TRANSMITTER CIRCUIT 5.7 UHF PLL CIRCUIT Figure 5-6PLL Circuit UHF5.7.2 VCO CIRCUIT 5.7.3 UHF POWER SUPPLY5.7.4 UHF CPU IC1 PORT ALLOCATION November5.7.6 UHF PORT EXPANDER IC13 MAIN UNIT 5.7.5 UHF I/O EXPANDER IC12 MAIN UNITNovember Part No.Test Setup SECTION 6 ADJUSTMENT PROCEDUREFigure 6.1 GENERALFigure 6-2Screen Display Example Figure 6-3Test Cable Schematic6.1.2 TEST CHANNELS 6.1.3 TEST CABLEADJUST /X /Y Table 6-1VHF Test FrequenciesTable 6-2UHF Test Frequencies VHF ADJUSTMENTS VHF ADJUSTMENTS6.2 PRELIMINARY SETUP 6.3 PLL ADJUSTMENT VHF MODELSFigure 6-4VHF Adjustment Points VHF ADJUSTMENTS CONT’DVHF ADJUSTMENTS CONT’D 6.5 RECEIVER ADJUSTMENTS VHF MODELSVHF ADJUSTMENTS CONT’D Figure 6-5Beep Tone Level Adjustment6.7TRANSMITTER ADJUSTMENTS UHF MODELS UHF ADJUSTMENTS6.6 PLL ADJUSTMENT UHF MODELS 6.7.4 DTCS WAVEFORM ADJUST UHF ADJUSTMENTS CONT’DFigure 6-6UHF Adjustment Points UHF ADJUSTMENTS CONT’D 6.8 RECEIVER ADJUSTMENTS UHF MODELSæçìíýõ9+ôý0$,1ý81,7 SECTION 7 PARTS LIST7610 VHF Main Unit HVFULSWLRQHVFULSWLRQ 76105 VHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7610 VHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7610 VHF Main UnitHVFULSWLRQ November Part No.HVFULSWLRQ 7610 VHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7610 VHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7610 VHF Main UnitHVFULSWLRQ November7640 UHF Main Unit æçéíýõ8+ôý0$,1ý81,77610 VHF Main Unit HVFULSWLRQHVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ November7640 UHF Main Unit 5HIý1RïHVFULSWLRQ HVFULSWLRQHVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ November Part No.HVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ NovemberHVFULSWLRQ 7640 UHF Main UnitHVFULSWLRQ November Part No.HVFULSWLRQ 7640 UHF Main UnitNovember 7-17Front Unit All Models 5217ý81,7 õ9+ý$1ý8+ý02/6ô7640 UHF Main Unit 5HIý1RïHVFULSWLRQ Front Unit All ModelsHVFULSWLRQ Novemberæçéíýõ8+ôý&+$66,6ý3$576 æçìíýõ9+ôý&+$66,6ý3$576Chassis Parts Front Unit All Models7-21 VHF 7610 EXPLODED VIEWNovember Part No.UHF 7640 EXPLODED VIEW ←FOLDOUT VHF Exploded ViewFRONT UNIT VHF 7610 BLOCK DIAGRAMMAIN UNIT VHF 7610 Diode Basing Diagrams VHF 7610 Transistor Basing DiagramsVHF 7610 MAIN BOARD BOTTOM VIEW FOLDOUT →Part No. VHF 7610 MAIN BOARD TOP VIEWNovember VHF MAIN UNIT VHF 7610 MAIN BOARD SCHEMATICPart No. UHF 7640 BLOCK DIAGRAMNovember November FOLDOUT →UHF 7640 MAIN BOARD BOTTOM VIEW J4 T o O p tion al Un it UHF 7640 MAIN BOARD TOP VIEWJ2 T o S p kr J5 T o O p t Ca bleUHF 7640 MAIN BOARD SCHEMATIC VHF/UHF FRONT UNIT BOARD BOTTOM VIEW VHF/UHF FRONT UNIT BOARD TOP VIEWFRONT UNIT VHF/UHF FRONT UNIT SCHEMATICUHF 7640 Diode Basing Diagrams UHF 7640 Transistor Basing DiagramsTRANSISTORS AND FETS • DIODES