Kenwood TM 281A User Manual

The Kenwood TM 281A is a 65W VHF FM transceiver designed for mobile operation in the 144-148 MHz amateur radio band. Featuring a large LCD display, rugged metal construction, simple operation with 207 memory channels, programmable scan functions, DTMF memory, and various scanning modes. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Accessories 7. Operating Modes 8. Memory Functions 9. Care & Maintenance 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Main unit with LCD display, microphone, mounting bracket, DC power cable, and hardware.

Feature	Description
Frequency Range	144-148 MHz (Amateur VHF Band)
Output Power	65W High / 10W Low (selectable)
Memory Channels	207 memory channels
Display	Large LCD with backlight
Scan Functions	Programmable scan, memory scan, band scan
DTMF Memory	16 DTMF memory channels
Construction	Rugged metal chassis
Power Requirement	13.8V DC ±15%
Current Drain	Receive: 0.5A (max audio), Transmit: 16A (65W)
Dimensions	140(W) x 40(H) x 158(D) mm

Installation

Unpack and inspect contents. Select suitable mounting location in vehicle.

Mount the unit: Use provided bracket to securely mount in vehicle.
Connect power: Connect red wire to positive (+) terminal, black wire to negative (-) terminal of vehicle battery.
Connect antenna: Use appropriate VHF antenna with PL-259 connector.
Connect microphone: Plug microphone into front panel connector.

WARNING! Ensure proper fuse protection (15A recommended). Route cables away from moving parts and hot surfaces.

First-Time Setup

Power on unit; configure basic settings.

Set squelch: Adjust SQL control until background noise disappears.
Set volume: Adjust VOL control to comfortable listening level.
Select frequency: Use main dial or keypad to select operating frequency.
Set power level: Press LOW key to toggle between 65W and 10W output.
Program memories: Store frequently used frequencies in memory channels.

CAUTION! Ensure proper antenna connection before transmitting to prevent damage to radio.

Specifications

Frequency Coverage: 144-148 MHz (VHF)
Mode: FM
Power Output: 65W High / 10W Low
Memory Channels: 207 (including 1 call channel)
Sensitivity: 0.16μV typical (12dB SINAD)
Selectivity: 12kHz (-6dB), 24kHz (-60dB)
Audio Output: 2W at 8Ω (10% distortion)
Power Supply: 13.8V DC negative ground
Current Drain: Receive: 0.5A, Transmit: 16A (65W)
Operating Temperature: -20°C to +60°C

Controls and Settings

Front Panel: POWER/VOL control, SQL control, main tuning dial, function keys.

Microphone: PTT, UP/DOWN keys, function keys, numeric keypad.

Basic Controls: POWER/VOL (rotate for volume, push for power), SQL (squelch control), main dial (frequency selection). Function Keys: LOW (power selection), LAMP (display backlight), LOCK (key lock), MHZ (MHz step), V/M (VFO/Memory selection), DUAL (dual watch), SCAN (scan operation), TONE (CTCSS/DCS), SET (function setup).

Connecting Accessories

External Speaker: Use external speaker jack for additional audio output. Data Port: For packet radio or other data applications. Remote Control: Optional remote control head kit available.

Turn off radio before connecting accessories.
Use appropriate cables and connectors.
Ensure proper polarity and connections.

Tip: Refer to accessory manuals for specific connection instructions.

Operating Modes

VFO Mode: Direct frequency entry and tuning. Memory Mode: Recall stored frequencies. Scan Modes: Memory scan, band scan, program scan.

Select VFO/Memory: Press V/M to toggle between modes.
Enter frequency: Use keypad or main dial.
Store memory: Press F then MR to store current frequency.
Start scan: Press SCAN to begin scanning.
Dual watch: Press DUAL to monitor current frequency and call channel.
Tone operation: Press TONE to access CTCSS/DCS functions.

WARNING! Transmit only on authorized amateur radio frequencies with proper license.

Memory Functions

Store frequencies with names, tones, and other settings. Memory Channels: 207 total (including 1 call channel). Memory Groups: Organize memories into groups for easy access.

Care & Maintenance

Keep unit clean and dry. Use soft cloth for cleaning; avoid chemicals. Periodically check connections and cables for damage.

CAUTION! Do not use solvents or abrasive cleaners. Keep away from moisture and extreme temperatures.

Regulatory Information

FCC Part 97: Certified for amateur radio service. This device complies with Part 15 of FCC Rules. Operation subject to condition that device does not cause harmful interference. Copyright © Kenwood Corporation. For support, visit www.kenwood.com or contact authorized Kenwood dealer.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Power connection/fuse	Check power connections; verify fuse; ensure proper voltage.
No reception	Antenna/squelch	Check antenna connection; adjust squelch control; verify frequency.
No transmission	PTT/microphone	Check microphone connection; verify PTT operation; check power setting.
Poor audio	Speaker/volume	Adjust volume; check speaker connection; verify audio settings.
Memory lost	Power interruption	Re-enter memory data; check power connections.

Reset: Turn off while holding LAMP key to reset to factory defaults.

Service: Contact authorized Kenwood service center; www.kenwood.com