Kenwood TL 922 Service Manual

The Kenwood TL 922 is a high-performance amateur radio transceiver featuring 160-10 meter coverage, 200W PEP output, built-in antenna tuner, dual VFOs, comprehensive DSP filtering, multiple operating modes including SSB, CW, AM, FM, and RTTY. This service manual provides detailed technical information for maintenance, repair, and adjustment procedures for qualified service technicians.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Descriptions 4. Alignment Procedures 5. Troubleshooting Guide 6. Parts List 7. PCB Layouts 8. Voltage Charts 9. Mechanical Assembly 10. Service Notes 11. Safety Precautions

Technical Specifications

Complete technical specifications and performance characteristics of the Kenwood TL 922 transceiver.

Parameter	Specification
Frequency Coverage	1.8-30 MHz (160-10 meters)
Output Power	200W PEP (SSB), 200W (CW), 60W (AM)
Modes	USB, LSB, CW, AM, FM, RTTY
Sensitivity	0.25μV for 10dB S/N (SSB)
Selectivity	2.4kHz (-6dB), 4.4kHz (-60dB)
Image Rejection	>70dB
IF Rejection	>70dB
Power Requirements	13.8V DC ±15%, 22A max
Dimensions	280(W) × 105(H) × 310(D) mm
Weight	6.5 kg

Block Diagram Overview

System block diagram showing signal flow and major circuit sections.

RF Front End: Preselector and RF amplifier stages
First Mixer: Converts RF to first IF at 69.0115 MHz
First IF Amplifier: 69.0115 MHz amplification and filtering
Second Mixer: Converts to second IF at 8.83 MHz
DSP Section: Digital signal processing for filtering and noise reduction
Audio Section: Final audio amplification and output
Power Supply: 13.8V DC regulation and distribution

WARNING! High voltages present in RF power amplifier section. Exercise extreme caution.

Circuit Descriptions

Detailed circuit analysis of major functional blocks.

Receiver Section: RF input through audio output signal path
Transmitter Section: Microphone input through RF power amplifier
VFO System: Dual VFO operation and frequency synthesis
Control System: Microprocessor control and user interface
Power Supply: Voltage regulation and distribution circuits
Antenna Tuner: Automatic antenna matching network

CAUTION! Static sensitive components. Use proper ESD protection.

Alignment Procedures

Receiver Alignment: RF amplifier, mixer, and IF strip adjustments
Transmitter Alignment: Driver and final amplifier tuning
VFO Alignment: PLL and VCO calibration procedures
Filter Alignment: Crystal and ceramic filter adjustments
Meter Calibration: S-meter and power meter calibration
Test Equipment Required: Signal generator, oscilloscope, power meter, frequency counter
Alignment Points: All test points and adjustment locations marked
Performance Verification: Final performance check procedures

Troubleshooting Guide

Systematic troubleshooting procedures for common problems.

Symptom/Cause Analysis: No receive, weak receive, no transmit, low power, frequency error, display issues.

Symptom	Possible Cause	Corrective Action
No power	Power supply fault	Check DC input, fuses, regulator circuits
No receive audio	Audio amp failure	Check audio IC voltages, speaker connections
Low power output	PA stage fault	Check final transistors, bias circuits
Frequency error	VFO/PLL fault	Check reference oscillator, PLL lock
Display problems	Display driver	Check LCD connections, driver IC

Parts List

Complete component listing with part numbers and specifications.

Semiconductors: Transistors, diodes, ICs with full specifications
Passive Components: Resistors, capacitors, inductors values and tolerances
Mechanical Parts: Hardware, connectors, switches, knobs
PCB Assemblies: Main board, display board, control board

Tip: Use genuine Kenwood replacement parts for best performance.

PCB Layouts

Detailed printed circuit board layouts and component locations.

Main Board: Component side and solder side views
Display Board: LCD and control interface layout
RF Board: RF amplifier and filter section layout
Power Supply Board: Regulator and power distribution layout
Interconnection Diagram: Board-to-board wiring guide
Test Points: All measurement and test point locations
Grounding Scheme: RF and digital ground separation
Shielding: RF shielding locations and removal procedures

WARNING! Observe proper RF safety procedures during testing.

Voltage Charts

Complete DC voltage measurements under normal operating conditions.

Test Point	Voltage (Receive)	Voltage (Transmit)
TP1 (VCC)	+13.8V	+13.8V
TP2 (VREG1)	+8.0V	+8.0V
TP3 (VREG2)	+5.0V	+5.0V
TP4 (VFO)	+12.0V	+12.0V
TP5 (PA Bias)	+0.6V	+0.8V

Mechanical Assembly

Mechanical assembly and disassembly procedures.

Case removal, board extraction, front panel service, heat sink maintenance, fan replacement, connector servicing.

Service Notes

Important service bulletins and field modifications.

Known issues, recommended upgrades, factory service bulletins, component change notices, firmware updates.

Safety Precautions

Critical safety information for service personnel.

Hazard	Precaution	Protection Required
High Voltage	RF power amplifier	Discharge capacitors before service
RF Radiation	Transmitter operation	Never operate with covers removed
Heat	Power transistors	Allow cool-down before handling
ESD	Semiconductors	Use grounded workstations
Sharp Edges	Chassis and heatsinks	Wear protective gloves

Service Contact: Authorized Kenwood service centers only.

Technical Support: Kenwood technical service department