Kenwood TM 742A Manual

The Kenwood TM 742A is a versatile multi-band amateur radio transceiver covering 2 meters, 70 cm, and 23 cm bands. This all-mode radio features FM, SSB, CW, and AM operation with cross-band repeat capability, extensive memory channels, built-in CTCSS/DCS, and comprehensive scanning functions. Below are key sections covering operation, features, installation, programming, and troubleshooting.

Features at a Glance

Key components: Multi-band transceiver unit, microphone, DC power cable, mounting brackets, and user manual.

Feature	Description
Frequency Coverage	144-148 MHz (2m), 430-450 MHz (70cm), 1240-1300 MHz (23cm)
Operating Modes	FM, SSB, CW, AM
Output Power	50W (2m), 35W (70cm), 10W (23cm)
Memory Channels	100 regular + 10 scan edges
Cross-band Repeat	Full duplex cross-band repeating capability
CTCSS/DCS	Built-in encode/decode with 50 CTCSS tones and 104 DCS codes
Scanning	Programmable band scan, memory scan, and priority watch
Power Requirements	13.8V DC ±15%
Antenna Connectors	SO-239 (2m), N-type (70cm/23cm)
Microphone Connector	8-pin modular jack

Installation

Unpack and inspect all components. Choose suitable mounting location.

1. Mounting: Use provided brackets to secure unit in vehicle or base station location.
2. Power Connection: Connect red wire to positive (+) terminal, black wire to negative (-) terminal of 13.8V DC power source.
3. Antenna Installation: Connect appropriate antennas to SO-239 (2m) and N-type (70cm/23cm) connectors.
4. Microphone Connection: Plug 8-pin microphone connector into front panel jack.

WARNING! Ensure proper grounding and fuse protection. Do not operate without proper antennas connected.

Basic Operation

Power on unit; adjust squelch and volume controls.

1. Band Selection: Press BAND button to cycle through 2m, 70cm, and 23cm bands.
2. Frequency Tuning: Use main tuning dial or UP/DOWN buttons to select frequency.
3. Mode Selection: Press MODE button to select FM, SSB, CW, or AM operation.
4. Transmit: Press and hold PTT on microphone to transmit; release to receive.
5. Power Adjustment: Use PWR button to select high, medium, or low power output.

CAUTION! Ensure you have proper amateur radio license for your country before transmitting.

Specifications

• Frequency Range: 144-148 MHz, 430-450 MHz, 1240-1300 MHz
• Output Power: 50W (2m), 35W (70cm), 10W (23cm)
• Power Supply: 13.8V DC negative ground
• Current Drain: Receive: 1.2A max, Transmit: 12A max
• Modulation System: Variable reactance FM, balanced modulator SSB/AM
• Spurious Emission: Better than -60 dB
• Sensitivity: FM: 0.16μV (12dB SINAD), SSB/CW: 0.25μV (10dB S/N)
• Audio Output: 2W at 10% distortion into 8Ω
• Dimensions: 165(W) × 55(H) × 190(D) mm
• Weight: 2.2 kg

Controls and Functions

Front Panel: POWER, VOLUME, SQUELCH, BAND, MODE, PWR, SQL/OFF, MHz/SCAN, V/M, F/W, A/B, DUAL, TONE, LOCK, and main tuning dial.

Microphone: PTT, UP/DOWN buttons, 16-key DTMF pad, function buttons.

Menu Functions: Access by holding F/W button. Includes CTCSS/DCS setup, scan parameters, memory management, display settings, and system configuration. Tone Encode/Decode: Programmable CTCSS and DCS for repeater access and private calling.

Memory Programming

Store frequently used frequencies and settings in memory channels.

1. Select desired frequency and mode.
2. Press V/M button to enter memory mode.
3. Use tuning dial to select memory channel number.
4. Hold F/W button and press MR/CALL to store current settings.
5. Repeat for additional memory channels.

Tip: Memory channels store frequency, mode, CTCSS/DCS settings, and power level.

Cross-band Operation

Full duplex cross-band repeating capability.

1. Enable cross-band: Press DUAL button.
2. Set receive frequency on one band and transmit frequency on another band.
3. Adjust power levels and CTCSS/DCS as needed.
4. Monitor both frequencies simultaneously.

WARNING! Ensure cross-band repeat operation complies with local regulations and license privileges.

Scanning Functions

Multiple scanning modes for monitoring activity.

1. Band Scan: Automatically scans entire selected band.
2. Memory Scan: Scans all programmed memory channels.
3. Programmable Scan: Set scan limits with scan edge memories.
4. Priority Watch: Monitors priority channel while scanning.

Access scan functions via MHz/SCAN button and menu settings.

Maintenance

Keep unit clean and dry. Periodically check connections and antennas.

CAUTION! Disconnect power before cleaning. Use only dry cloth; avoid liquids and chemicals.

Regulatory Information

FCC Part 97: Certified for amateur radio service. This device must accept any interference received, including interference that may cause undesired operation. Manufactured by Kenwood Corporation. For technical support and service, contact authorized Kenwood service centers.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Power connection/fuse	Check power connections; verify fuse is intact; ensure proper voltage.
No transmit	PTT/microphone	Check microphone connection; verify PTT operation; check antenna.
Poor reception	Antenna/tuning	Verify antenna connections; check antenna SWR; adjust squelch.
Memory loss	Backup battery	Memory backup battery may need replacement after several years.
Overheating	Ventilation/power	Ensure adequate ventilation; check for proper power supply voltage.

Reset: Power off unit, hold F/W and LOCK buttons while powering on to reset to factory defaults.

Service: Contact authorized Kenwood service center for repairs.