Kenwood TK 780 Service Manual

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2 TK-780/ H GENERAL INTRODUCTION SCOPE OF THIS MANUAL This manual is intended for use by experienced techni- cians familiar with similar types of commercial grade com- munications equipment. It contains all required service infor- mation for the equipment and is current as of this publica- tion date. Changes which may occur after publication are covered by either Service Bulletins or Manual Revisions, which are issued as required. ORDERING REPLACEMENT PARTS When ordering replacement parts or equipment informa- tion, the full part identification number should be included. This applies to all parts : components, kits, and chassis. If the part number is not known, include the chassis or kit number of which it is a part and a sufficient description of the required component, for proper identification. PERSONNEL SAFETY The following precautions are recommended for person- nel safety : - DO NOT transmit if someone is within two feet (0.6 meter) of the antenna. - DO NOT transmit until all RF connectors are secure and any open connectors are properly terminated. - SHUT OFF this equipment when near electrical blasting caps or while in an explosive atmosphere. - All equipment should be properly grounded before power-up for safe operation. - This equipment should be serviced by only qualified tech- nicians. PRE-INSTALLATION CONSIDERNATIONS 1. UNPACKING Unpack the radio from its shipping container and check for accessory items. If any item is missing, please contact KENWOOD immediately. 2. LICENSING REQUIREMENTS Federal regulations require a station license for each ra- dio installation (mobile or base) be obtained by the equip- ment owner. The licensee is responsible for ensuring trans- mitter power, frequency, and deviation are within the limits permitted by the station license. Transmitter adjustments may be performed only by a li- censed technician holding an FCC first, second or general class commercial radiotelephone operators license. There is no license required to install or operate the radio. 3. PRE-INSTALLATION CHECKOUT 3-1. Introduction Each radio is adjusted and tested before shipment. How- ever, it is recommended that receiver and transmitter opera- tion be checked for proper operation before installation. 3-2. Testing The radio should be tested complete with all cabling and accessories as they will be connected in the final installa- tion. Transmitter frequency, deviation, and power output should be checked, as should receiver sensitivity, squelch operation, and audio output. QT equipment operation should be verified. 4. PLANNING THE INSTALLATION 4-1. General Inspect the vehicle and determine how and where the radio antenna and accessories will be mounted. Plan cable runs for protection against pinching or crush- ing wiring, and radio installation to prevent overheating. 4-2. Antenna The favored location for an antenna is in the center of a large, flat conductive area, usually at the roof center. The trunk lid is preferred, bond the trunk lid and vehicle chassis using ground straps to ensure the lid is at chassis ground. 4-3. Radio The universal mount bracket allows the radio to be mounted in a variety of ways. Be sure the mounting surface is adequate to support the radios weight. Allow sufficient space around the radio for air cooling. Position the radio close enough to the vehicle operator to permit easy access to the controls when driving. 4-4. DC Power and wiring 1. This radio may be installed in negative ground electrical systems only. Reverse polarity will cause the cable fuse to blow. Check the vehicle ground polarity before installa- tion to prevent wasted time and effort. 2.You must connect the positive power lead directly to the positive terminal of the vehicle battery. Never connect the lead to any other positive power source, such as a cigarette lighter jack or fuse terminals. CAUTION If DC power is to be controlled by the vehicle ignition switch, a switching relay should be used to switch the posi- tive power lead. The vehicle ignition switch then controls DC to the relay coil. 3.You must also connect the ground lead directly to the negative terminal of the vehicle battery. 4. The cable provided with the radio is sufficient to handle the maximum radio current demand. If the cable must be extended, be sure the additional wire is sufficient for the current to be carried and length of the added lead.

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3 TK-780 / H 5. INSTALLATION PLANNING -“ CONTROL STATIONS 5-1. Antenna system Control station. The antenna system selection depends on many factors and is beyond the scope of this manual. Your KENWOOD dealer can help you select an antenna sys- tem that will best serve your particular needs. 5-2. Radio location Select a convenient location for your control station radio which is as close as practical to the antenna cable entry point. Secondly, use your systems power supply (which supplies the voltage and current required for your system). Make sure sufficient air can flow around the radio and power supply to allow adequate cooling. SERVICE This radio is designed for easy servicing. Refer to the schematic diagrams, printed circuit board views, and align- ment procedures contained in this manual. Note When you modify your radio as described in system set- up, take the following precaution. The rating of pin 7 (SB) of the accessory connector cable (KCT-19) on the rear of the radio is 13.6V (1A). Insert a 1A fuse if you use the SB pin for external equipment. Accessory connector cable (KCT-19) If you do not intend to use the 3.5-mm jack for the exter- nal speaker, fit the supplied speaker-jack cap (B09-0235-05) to stop dust and sand getting in. GENERAL / OPERATING FEATURES Speaker-jack cap (B09-0235-05) 1. Operation Features The TK-780/780H is a VHF FM radio designed to operate in both trunking format (LTR model) and conventional for- mat (Conventional model). The programmable features are summarized. Model Trunking format Trunking mode Conventional format Conventional mode 1-1. Trunking Format This format can handle up to 32 systems with up to 250 groups in each system. The transceiver can be used in both trunked mode and conventional mode. Systems, groups, and their functions are programmed. 1-2. Conventional Format This format can handle up to 250 groups with 250 chan- nels in each group. The transceiver can be used only in con- ventional mode. Groups, channels, and their functions are programmed. 2. Transceiver Controls and Indicators (Fig. 1) 2-1. Front Panel Controls All the keys on the front panel are momentary-type push buttons. The functions of these keys are explained below. -POWER key Transceiver POWER key. When the power is switched off, all the parameters, such as the system and group in trunking format, and the group and channel in conventional format, are stored in memory. When the power is switched on again, the transceiver returns to the previous conditions. -SYSTEM UP/DOWN key (Trunking format, programmable) -GROUP UP/DOWN key (Conventional format, programmable) -SCAN key (Programmable) -MONITOR key (Programmable) -A, B, C and D key (Programmable) -VOLUME UP/DOWN key (Programmable) -BUSY/TX LED The BUSY indicator (Green LED) shows that the channel is in use. The TX indicator (Red LED) shows that you are transmitting. 1 3 + -“ 7 6 13 15

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ADJUSTMENT Measurement Test- equipmentUnitTerminalAdjustment Unit Parts MethodSpecifications/Remarks Condition Item 56 TK-780/ H 11. Fine LTR 1) Set test mode Power meter Rear ANT 1.0kHz (Wide)±50Hz (Wide/Narrow) Select FLTR in tuning mode. Deviation panel 0.75kHz (Narrow) L FLTR meter deviation meter filter Oscilloscope LPF : 3kHz HPF : OFF AF VTVM Front MIC PTT : ON AG panel 2) C FLTR PTT : ON 3) H FLTR PTT : ON 12. DTMF 1) Set test mode 3.0kHz (Wide)±0.2kHz (Wide) deviation Select DTMF in tuning mode. 1.5kHz (Narrow)±0.1kHz (Narrow) Deviation meter filter LPF : 15kHz HPF : OFF PTT : ON 13. MSK 1) Set test mode 3.0kHz (Wide)±0.1kHz (Wide/Narrow) deviation Select FMSK in tuning mode. 1.5kHz (Narrow) Deviation meter filter LPF : 15kHz HPF : OFF PTT : ON 14. TONE 1) Set test mode 3.0kHz (Wide)±0.1kHz (Wide/Narrow) deviation Select TONE in tuning mode. 1.5kHz (Narrow) Deviation meter filter LPF : 15kHz HPF : OFF PTT : ON