Kenwood TM V71A Service Manual

The Kenwood TM V71A is a dual-band mobile transceiver operating on 144MHz and 430MHz amateur radio bands. This service manual provides comprehensive technical information for installation, operation, maintenance, and repair. Features include cross-band repeat function, 50W output power on VHF and 35W on UHF, wide frequency coverage, multiple memory channels, CTCSS/DCS encode/decode, and versatile scanning functions.

Technical Specifications

Complete technical specifications and performance characteristics of the TM V71A transceiver.

Parameter	Specification
Frequency Range	VHF: 136-174MHz, UHF: 420-470MHz
Output Power	VHF: 5-50W, UHF: 5-35W (selectable)
Power Supply	13.8V DC ±15% (negative ground)
Current Drain	Receive: 0.8A, Transmit: 13A max
Modulation System	16KΦF3E (FM)
Antenna Impedance	50 ohms
Operating Temperature	-20°C to +60°C
Dimensions	140(W) × 40(H) × 180(D) mm
Weight	Approx. 1.2 kg
Memory Channels	200 memory channels + 6 scan edges

Installation Procedures

Proper installation guidelines for mobile and fixed station operation.

1. Mounting: Secure the main unit in a well-ventilated area away from direct sunlight and moisture.
2. Power Connection: Connect red wire to positive terminal, black wire to negative ground.
3. Antenna Installation: Use appropriate dual-band antenna with 50 ohm impedance.
4. Control Head: Mount control head within easy reach using supplied bracket.
5. Cable Routing: Route all cables away from heat sources and moving parts.

WARNING! Ensure proper fuse protection (15A recommended) in power line. Verify correct polarity before applying power.

Front Panel Controls

Detailed description of all front panel controls and indicators.

Main Controls: POWER/VOLUME knob, SQL knob, Function (F) key, A/B band selector, VFO/MR button, HM/RV key, CALL key, DIAL knob, MIC connector.

Display Indicators: Dual frequency display, S/RF meter, SQL indicator, busy indicator, TX/RX indicators, memory channel number, function indicators, band indicators, CTCSS/DCS indicators.

MIC Controls: PTT switch, UP/DOWN buttons, FUNCTION button, 16-key DTMF pad (optional).

Basic Operation

Fundamental operating procedures for the TM V71A transceiver.

1. Power On: Turn POWER/VOLUME knob clockwise.
2. Volume/Squelch: Adjust VOLUME for audio level, SQL for squelch threshold.
3. Frequency Selection: Use DIAL knob or keypad to select operating frequency.
4. Band Selection: Press A/B button to select between VHF and UHF bands.
5. Transmit: Press PTT on microphone to transmit, release to receive.
6. Power Selection: Use [F] + [LOW] to select output power level.

Note: Allow 30 seconds warm-up time for frequency stability.

Advanced Functions

Advanced features and special operating modes.

• Dual Watch: Monitor two frequencies simultaneously on same band.
• Priority Watch: Monitor priority channel while operating on main frequency.
• CTCSS/DCS: Encode/decode for selective calling and repeater access.
• Auto Repeater Shift: Automatic repeater offset selection.
• Tone Burst: 1750Hz tone burst for European repeater access.
• Scan Functions: Programmable band scan, memory scan, priority scan.
• DTMF Operation: DTMF encoding for autopatch and remote control.

Memory Operations

Memory channel programming and management.

1. Memory Store: Select frequency → Press [F] → Press [MR] → Select channel number.
2. Memory Recall: Press [MR] → Select desired memory channel.
3. Memory Clear: Select memory channel → Press [F] + [MHz] for 2 seconds.
4. Memory Name: Assign alphanumeric names to memory channels.
5. Memory Group: Organize memories into groups for easier access.
6. Memory Scan: Scan programmed memory channels.

Tip: Backup memory contents before performing master reset.

Cross-band Operation

Cross-band repeat function and dual-band operations.

Cross-band Repeat: Automatically retransmits received signal on opposite band. Enable via menu setting. Set input and output frequencies with appropriate offsets.

Dual-band Operation: Simultaneous operation on VHF and UHF bands. Independent control of each band with separate volume and squelch settings.

WARNING! Ensure compliance with local regulations when using cross-band repeat function. Some jurisdictions restrict or prohibit cross-band repeating.

Maintenance & Service

Routine maintenance and service procedures.

1. Cleaning: Use soft dry cloth for exterior. Avoid chemical cleaners.
2. Fuse Replacement: Replace with identical 15A fuse if blown.
3. Alignment: Refer to alignment procedures in service section.
4. Software Update: Check Kenwood website for firmware updates.
5. Preventive Maintenance: Regular inspection of cables and connectors.

CAUTION! Disconnect power before performing any internal maintenance. High voltages present inside unit.

Troubleshooting Guide

Common problems and solutions for the TM V71A.

Symptom	Possible Cause	Corrective Action
No power	Blown fuse, power cable	Check fuse, verify power connections, test voltage
No reception	Antenna, squelch setting	Check antenna connection, adjust squelch, verify frequency
No transmission	PTT, microphone, settings	Test microphone, check PTT switch, verify transmit frequency
Poor audio	Speaker, audio settings	Check speaker connection, adjust audio settings, test microphone
Memory loss	Backup battery	Replace internal backup battery, reprogram memories
Display issues	Ribbon cable, display	Check display cable connections, test display voltages

Parts List

Complete list of replacement parts and components.

• Main Unit Assembly: XXXXXXXXX-XXXX
• Control Head: XXXXXXXXX-XXXX
• Front Panel: XXXXXXXXX-XXXX
• Main PCB: XXXXXXXXX-XXXX
• RF Unit: XXXXXXXXX-XXXX
• Display Module: XXXXXXXXX-XXXX
• Backup Battery: CR2032 Lithium
• Fuse: 15A automotive type
• Mounting Bracket: XXXXXXXXX-XXXX
• Connection Cables: Various part numbers available

Circuit Diagrams

Reference circuit diagrams and block diagrams.

Block Diagram: Overall system block diagram showing signal flow and major components.

Schematic Diagrams: Complete circuit schematics for: - RF amplifier stages - PLL synthesizer - IF and detector circuits - Audio processing - Power supply - Control logic

PCB Layouts: Component placement and routing diagrams for main board and control head.

Alignment Procedures: Step-by-step alignment instructions with test point locations and required test equipment.