Kenwood TS-50S Service Manual

The Kenwood TS-50S is a compact HF transceiver covering 1.8-30 MHz with 100W output power, featuring built-in antenna tuner, DSP filtering, multiple operating modes including SSB, CW, AM, FM, and RTTY. This service manual provides comprehensive technical information for maintenance, repair, and adjustment procedures for qualified service technicians.

Technical Specifications

Complete technical specifications and performance characteristics of the Kenwood TS-50S transceiver.

Parameter	Specification
Frequency Coverage	1.8-30 MHz (all amateur bands)
Output Power	100W PEP (SSB), 100W (CW), 40W (AM), 25W (FM)
Modes	LSB, USB, CW, AM, FM, FSK
Sensitivity	0.25μV for 10dB S+N/N (SSB)
Selectivity	2.4kHz/1.8kHz/500Hz (SSB/CW/AM)
Power Supply	13.8V DC ±15%
Current Drain	Receive: 1.3A, Transmit: 22A max
Dimensions	240W × 85H × 260D mm
Weight	3.2 kg
Antenna Impedance	50 ohms unbalanced

Block Diagrams

System block diagrams showing signal flow and major circuit blocks.

1. RF Unit Block Diagram: Shows receiver front-end and transmitter final stages
2. IF Unit Block Diagram: DSP and filtering stages
3. Control Unit Block Diagram: Microprocessor and interface circuits
4. Power Supply Unit: Voltage regulation and distribution
5. Antenna Tuner Unit: AT-50 internal tuner circuitry

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

Circuit Descriptions

Detailed descriptions of major circuit sections and their operation.

1. Receiver Front End: RF amplifier, mixer, and first local oscillator
2. IF System: Crystal filters, IF amplifiers, and DSP processing
3. Transmitter Chain: Microphone amp, balanced modulator, driver, and PA stages
4. VFO and PLL: Frequency synthesis system
5. Control System: Microprocessor functions and user interface

CAUTION! Static sensitive components. Use proper grounding when handling circuit boards.

Alignment Procedures

• Receiver Alignment: RF amplifier, mixer, and IF strip adjustments
• Transmitter Alignment: Carrier balance, sideband suppression, power output
• PLL Alignment: VCO adjustment and loop lock verification
• DSP Alignment: Filter characteristics and noise reduction settings
• Meter Calibration: S-meter and power meter calibration
• Antenna Tuner: AT-50 tuner calibration and matching network adjustment
• Test Equipment Required: Spectrum analyzer, oscilloscope, RF generator, power meter, dummy load

Troubleshooting Guide

Systematic troubleshooting procedures for common problems.

Symptom	Possible Cause	Corrective Action
No power	Power supply, fuse, internal regulator	Check DC input, replace F1 fuse, verify Q26 regulator
No receive audio	Audio IC, volume control, speaker	Check IC8 audio amp, test speaker, verify AF gain control
Poor sensitivity	RF amp, mixer, AGC circuit	Test Q1 RF amp, check mixer diode, verify AGC voltage
No transmit	PA transistors, driver stage, PTT circuit	Check Q15-Q18 finals, test driver Q14, verify PTT switching
Frequency error	PLL unlock, reference oscillator	Check X1 reference, verify PLL lock voltage, test VCO

Parts List

Complete component listing with part numbers and specifications.

Major Components: Q1 (3SK74), Q15-Q18 (2SC2879), IC8 (LA4282), IC11 (DSP), X1 (10.240MHz)

Semiconductors: Complete listing of transistors, diodes, and integrated circuits

Passive Components: Resistors, capacitors, inductors with values and tolerances

Mechanical Parts: Hardware, connectors, knobs, and structural components

PCB Layouts

Printed circuit board layouts for all major assemblies.

1. Main Unit PCB: Component placement and trace routing
2. Front Panel PCB: Display and control interface
3. RF Unit PCB: Receiver front-end and transmitter PA
4. Power Supply PCB: Voltage regulation circuits
5. Antenna Tuner PCB: AT-50 matching network

Tip: Use proper soldering techniques and temperature-controlled iron for PCB work.

Schematic Diagrams

Complete schematic diagrams for all circuit sections.

1. Main Unit Schematic: Complete system schematic
2. Power Supply Schematic: Voltage regulation and distribution
3. RF Unit Schematic: Receiver and transmitter RF circuits
4. Control Unit Schematic: Microprocessor and interface
5. Display Unit Schematic: LCD and indicator circuits
6. Antenna Tuner Schematic: AT-50 automatic tuner

WARNING! High voltage present in power amplifier section. Discharge capacitors before servicing.

Mechanical Assembly

Mechanical assembly drawings and disassembly procedures.

Case Disassembly: Step-by-step chassis removal

Board Removal: Procedure for removing main PCB and sub-assemblies

Front Panel: Display and control assembly

Heat Sink: PA transistor mounting and thermal compound application

CAUTION! Handle LCD display carefully to avoid damage.

Service Notes

Important service notes and technical updates.

Firmware Updates: Procedure for microprocessor firmware updates

Common Failures: Known issues and recommended fixes

Modification Notes: Factory modifications and service bulletins

Test Points: Voltage and signal measurements at key test points

For technical support contact Kenwood service department or authorized service centers.