Kenwood TKR 720 Service Manual

The Kenwood TKR 720 is a professional-grade VHF/UHF repeater system designed for commercial and public safety applications. This service manual covers technical specifications, installation procedures, maintenance guidelines, troubleshooting, and repair instructions for qualified technicians. The TKR 720 features robust construction, advanced signaling capabilities, and reliable performance in demanding environments.

1. Technical Specifications 2. Installation Procedures 3. System Configuration 4. Maintenance Schedule 5. Troubleshooting Guide 6. Circuit Diagrams 7. Alignment Procedures 8. Parts List 9. Safety Precautions 10. Warranty Information

Technical Specifications

The Kenwood TKR 720 repeater system offers high-performance specifications for reliable communication operations.

Parameter	Specification
Frequency Range	VHF: 136-174 MHz, UHF: 400-470 MHz
Output Power	25W / 50W selectable
Power Supply	13.8V DC ±15%
Current Consumption	Standby: 0.5A, Transmit: 10A (50W)
Modulation	16KΦF3E (FM)
Channel Spacing	12.5/20/25 kHz
Operating Temperature	-30°C to +60°C
Dimensions	132(W) × 45(H) × 230(D) mm
Weight	Approx. 2.5 kg
Connectors	Antenna, Power, Remote, Data

Installation Procedures

Proper installation is critical for optimal performance and reliability.

Mounting: Secure unit in well-ventilated area using provided brackets.
Power Connection: Connect 13.8V DC power supply with proper polarity.
Antenna Installation: Use low-loss coaxial cable (minimum 50 ohm).
Grounding: Ensure proper grounding for lightning protection.
Cable Routing: Separate power and RF cables to minimize interference.

WARNING! Installation should be performed by qualified personnel only. Ensure proper ventilation and grounding.

System Configuration

Configure system parameters using programming software and front panel controls.

Frequency Programming: Use KPG-46D programming software.
CTCSS/DCS: Set tone squelch parameters as required.
Time-out Timer: Configure transmit time limits.
Power Settings: Select appropriate output power level.
Scan Settings: Program priority channels and scan lists.

NOTE: Backup configuration settings before making changes.

Maintenance Schedule

Regular maintenance ensures long-term reliability and performance.

Daily: Visual inspection, check status indicators.
Weekly: Verify power output and receiver sensitivity.
Monthly: Clean filters, check connections and cables.
Quarterly: Perform complete alignment check.
Annually: Comprehensive performance testing and calibration.

Troubleshooting Guide

Common issues and recommended solutions for field service.

Symptom	Possible Cause	Corrective Action
No power	Power supply fault	Check DC input voltage and polarity
Poor reception	Antenna system	Verify antenna connection and SWR
No transmit	PA module	Check final amplifier and driver stages
Overheating	Ventilation	Clean filters, ensure adequate airflow
Intermittent operation	Connectors	Inspect and reseat all connections

Circuit Diagrams

Detailed schematics for main board, power supply, and RF sections.

Main Control Unit Block Diagram
RF Power Amplifier Circuit
Power Supply Schematic
Frequency Synthesizer Diagram
Audio Processing Circuit

NOTE: Refer to detailed schematics in appendix for component-level repair.

Alignment Procedures

Step-by-step alignment instructions using proper test equipment.

Receiver Alignment: Adjust for optimal sensitivity and selectivity.
Transmitter Alignment: Set frequency deviation and power output.
PLL Alignment: Verify lock range and stability.
Audio Alignment: Adjust modulation and audio response.
Final Testing: Verify all parameters meet specifications.

CAUTION! Use calibrated test equipment. Follow ESD precautions.

Parts List

Complete list of replacement parts and components.

Part Number	Description	Qty
K12345678	Main PCB Assembly	1
K12345679	RF Power Module	1
K12345680	Front Panel Assembly	1
K12345681	Power Supply Board	1
K12345682	Cooling Fan Assembly	1

Safety Precautions

Critical safety information for service personnel.

Disconnect power before servicing
Use proper grounding techniques
Observe RF radiation safety
Follow ESD protection procedures
Use approved replacement parts only

WARNING! High voltages present. Only qualified technicians should perform internal repairs.

Warranty Information

Kenwood TKR 720 warranty terms and service support.

Standard warranty: 3 years parts and labor. Warranty void if unit is modified or repaired by unauthorized personnel. For service support, contact authorized Kenwood service centers. Technical support available at www.kenwood.com or 1-800-KENWOOD.