Kenwood TM 281A Manual

The Kenwood TM 281A is a 65W VHF FM transceiver designed for mobile operation in the 144-148 MHz amateur band. Featuring a large LCD display, rugged metal construction, simple operation, and programmable memory channels. Below are key sections for safety, features, installation, setup, operation, and 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/25W/5W selectable
Memory Channels	200 programmable memories
Display	Large LCD with backlight
Construction	Rugged metal chassis
Power Requirement	13.8V DC negative ground
Microphone Connector	8-pin modular jack
Antenna Connector	SO-239 (UHF female)
Size	140(W) x 40(H) x 158(D) mm
Weight	1.1 kg

Installation

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

1. Mounting: Use provided bracket to secure radio in desired location.
2. Power Connection: Connect red wire to positive (+) terminal, black wire to negative (-) terminal of 13.8V DC power source.
3. Antenna Connection: Connect antenna to SO-239 connector using proper coaxial cable.
4. Microphone Connection: Plug microphone into 8-pin connector on front panel.

WARNING! Ensure proper fuse rating (15A recommended). Connect to negative ground system only.

First-Time Setup

Power on radio; configure basic settings.

1. Set frequency: Use main dial to select operating frequency.
2. Adjust squelch: Turn SQL control until background noise disappears.
3. Set power level: Press FUNC then PWR to select 65W/25W/5W.
4. Program memories: Store frequently used frequencies in memory channels.
5. Set display contrast: Adjust via FUNC + DIMMER keys.

CAUTION! Ensure proper antenna is connected before transmitting.

Specifications

• Frequency Coverage: 144-148 MHz (RX/TX)
• Mode: FM
• Output Power: 65W/25W/5W selectable
• Memory Channels: 200 channels
• Power Supply: 13.8V DC ±15%
• Current Drain: 15A max (at 65W transmit)
• Antenna Impedance: 50 ohms
• Microphone: 8-pin modular with UP/DOWN controls
• Operating Temperature: -20°C to +60°C
• Dimensions: 140(W) x 40(H) x 158(D) mm

Controls and Settings

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

Microphone: PTT, UP/DOWN buttons, optional function controls.

Basic Controls: VOLUME (power on/off), SQL (squelch control), Dial (frequency selection). Function Keys: FUNC (access secondary functions), PWR (power level selection), LAMP (display backlight), MHZ (MHz step selection), REV (repeater shift reverse), TONE (CTCSS encode), DCS (digital code squelch).

Connecting Accessories

External Speaker: Use SP jack on rear panel. Data Interface: Optional cable for PC programming. External Control: Remote control connections available.

1. Turn off radio before connecting accessories.
2. Use proper cables and connectors for each accessory type.
3. Ensure secure connections to prevent intermittent operation.

Tip: Use high-quality coaxial cable for antenna connection to minimize signal loss.

Operating Modes

Supports simplex and repeater operation.

1. Simplex Operation: Direct communication on same frequency.
2. Repeater Operation: Use offset (+/- 600 kHz typical) with CTCSS/DCS if required.
3. Memory Mode: Recall stored frequencies from memory channels.
4. Scan Modes: Band scan, memory scan, program scan.
5. Power Selection: Choose appropriate power level for operating conditions.

WARNING! Operate only within licensed amateur radio privileges.

Memory Functions

Store and recall up to 200 frequencies with associated settings.

1. Store Memory: Tune to desired frequency, press M.IN, select memory channel, press M.IN again.
2. Recall Memory: Press MR, select channel with dial or microphone buttons.
3. Memory Clear: Press FUNC + M.IN to clear selected memory channel.
4. Memory Scan: Press SCAN to scan programmed memory channels.

Care & Maintenance

Keep radio clean and dry. Use soft cloth for cleaning; avoid solvents.

CAUTION! Do not use chemical cleaners on display or controls. Keep vents clear for proper cooling.

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 DC connections; verify fuse; ensure proper polarity.
No transmission	Microphone/PTT	Check microphone connection; verify PTT operation; check antenna.
Poor reception	Antenna/squelch	Verify antenna connection; adjust squelch control; check coaxial cable.
Memory lost	Power interruption	Memory backup battery may need replacement; reprogram memories.
Overheating	Ventilation/power	Ensure adequate ventilation; reduce transmit power; check duty cycle.

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

Service: Contact authorized Kenwood service center for repairs.