Kenwood TKR 850 Service Manual

The Kenwood TKR 850 is a professional-grade VHF/UHF repeater system designed for commercial and public safety applications. This service manual provides comprehensive technical information for installation, maintenance, troubleshooting, and repair of the TKR 850 repeater system. Below are key sections covering specifications, installation procedures, maintenance guidelines, troubleshooting, and technical reference data.

1. Features at a Glance 2. Installation Procedures 3. Technical Specifications 4. Maintenance Guidelines 5. Control Head Operation 6. RF Unit Configuration 7. Programming and Setup 8. Alignment Procedures 9. Troubleshooting Guide 10. Parts List 11. Schematics and Diagrams

Features at a Glance

Key components: RF Unit, Control Head, Power Supply Unit, Duplexer, and associated interface cables.

Feature	Description
Frequency Range	VHF: 136-174 MHz, UHF: 400-470 MHz
Output Power	Up to 50W (VHF), 40W (UHF)
Channels	Up to 128 channels programmable
Duplex Operation	Full duplex with high isolation
Power Supply	13.8V DC nominal operation
Control Interface	RS-232C for programming and control
Temperature Range	-30°C to +60°C operating
Dimensions	RF Unit: 320(W) × 110(H) × 340(D) mm
Weight	Approximately 12 kg (complete system)
Modulation	16KΦF3E / 11KΦF3E

Installation Procedures

Unpack and inspect all components. Ensure proper mounting surface and adequate ventilation.

Mount RF Unit: Secure to stable surface using provided mounting brackets.
Connect Duplexer: Attach antenna cables to duplexer ports (TX, RX, ANT).
Power Connections: Connect 13.8V DC power supply with proper polarity.
Control Head: Connect control cable and mount in accessible location.
Antenna System: Install appropriate antenna for frequency band.

WARNING! Ensure proper grounding and lightning protection. Use only approved antennas and cables.

Technical Specifications

Frequency Stability: ±1.5 ppm (-30°C to +60°C)
Spurious Emission: -60 dB or better
Adjacent Channel Power: -70 dB or better
Audio Output: 2W at 10% distortion
Sensitivity: 0.25 μV typical for 12 dB SINAD
Selectivity: 70 dB typical at ±12.5 kHz
Intermodulation: 70 dB typical
Power Consumption: Approx. 15A at 13.8V DC (max power)
Cooling System: Temperature-controlled fan

Maintenance Guidelines

Regular maintenance ensures optimal performance and longevity.

Monthly: Check all cable connections and antenna system integrity.
Quarterly: Clean exterior surfaces and ventilation openings.
Annually: Perform complete system alignment and performance check.
As needed: Update firmware and programming as required.

CAUTION! Disconnect power before performing any internal maintenance. Use only approved replacement parts.

Control Head Operation

Front Panel Controls: POWER, CHANNEL selector, VOLUME, SQL, and function buttons.

Display Indicators: Channel number, TX/RX status, power level, error codes.

Menu Functions: Channel programming, power settings, time-out timer, scan configuration, CTCSS/DCS settings, system diagnostics.

RF Unit Configuration

Internal adjustments and configuration settings for optimal RF performance.

Power Adjustment: Set transmit power level for desired output.
Frequency Alignment: Adjust reference oscillator and VCO settings.
Modulation Balance: Set for proper deviation and audio quality.
Receiver Alignment: Optimize sensitivity and selectivity.

Tip: Use calibrated test equipment for all RF adjustments.

Programming and Setup

System programming via RS-232C interface using Kenwood programming software.

Connect programming cable to control head or RS-232C port.
Launch programming software and read current configuration.
Set frequencies, CTCSS/DCS codes, time-out timer, and other parameters.
Write configuration to repeater and verify operation.
Backup configuration file for future reference.

WARNING! Ensure proper licensing for all programmed frequencies. Follow local regulations.

Alignment Procedures

Detailed alignment procedures for maintaining optimal performance.

Circuit	Test Point	Adjustment	Specification
Reference Oscillator	TP1	TC1	±1.5 ppm
Transmit VCO	TP2	L1, L2	Lock voltage 2.5V ±0.5V
Receiver Front End	TP3	L3, L4	Max sensitivity
Modulator	TP4	RV1	±5 kHz deviation
Power Amplifier	TP5	RV2	50W (VHF), 40W (UHF)

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No power	Power supply/connections	Check DC input voltage and polarity; verify fuse
No transmit	PA failure/VCO unlock	Check PA voltages; verify VCO lock
Poor reception	Antenna/duplexer	Check antenna system; verify duplexer tuning
Distorted audio	Modulation/audio circuit	Adjust modulation balance; check audio components
Overheating	Fan/ventilation	Clean ventilation; verify fan operation
Control head error	Cable/interface	Check control cable; reset control head

Parts List

Essential replacement parts and components for service and repair.

Power Amplifier Module: Part #K-850-PA
RF Unit Main Board: Part #K-850-MB
Control Head Assembly: Part #K-850-CH
Power Supply Regulator: Part #K-850-PS
Cooling Fan Assembly: Part #K-850-FAN
Front Panel Display: Part #K-850-DISP
Main Fuse: 15A DC fuse
Control Cable: 8-pin modular cable

Schematics and Diagrams

Complete circuit diagrams and block diagrams for service reference.

RF Unit Block Diagram: Overall system architecture
Power Supply Schematic: DC power distribution
Transmitter Circuit: PA and driver stages
Receiver Circuit: Front end and IF stages
Control Interface: Microprocessor and interface circuits
Duplexer Schematic: Filter and isolation circuits

Service Contact: Authorized Kenwood service centers only. Refer to www.kenwood.com for service locations.