Hardwiring the Midland 15 Watt Radios

This article contains instructions for hardwiring the MXT115, MXT115 PRO, MXT275, and MXT295 PRO. 

The MXT115 and MXT275 use the MXTA33 power cable. The MXT115 PRO and the MXT295 PRO use the MXPW15 power cable. 

Tools & Materials Needed

• Wire strippers / crimpers
• Multimeter (for checking power/ground)
• Add-a-fuse kit (recommended for fuse box wiring)
• 15A inline fuse holder (if not already included in the radio power cord)
• Crimp connectors or solder/heat shrink
• Zip ties / cable loom (for wire management)
• Electrical tape

Step 1: Plan Your Install

1. Choose the radio location
   • The MXT275 has a detachable faceplate mic, so you can hide the main unit (glove box, under dash, center console) and mount the mic/controls where reachable.
2. Choose the power source
   • Option 1: Direct to vehicle fuse box using an add-a-fuse kit.
   • Option 2: Direct to battery (with fused positive line).
   • Option 3: Cigarette lighter plug (stock cord), but not true hardwire.
3. Choose a grounding point
   • Use a solid, bare metal chassis ground close to where you mount the radio.

Step 2: Identify Power Wires

The MXT275 power cord has two wires:

• Red = +12V (positive)
• Black = Ground (negative)

The radio requires a 12V DC supply, fused at 2A.

Step 3: Hardwiring Options

Option A: Fuse Box 

1. Locate your fuse box inside the cab.
2. Pick a circuit:
   • Switched power (radio turns on/off with ignition) → example: radio, wipers, or accessory fuse.
   • Constant power (radio always has power, must be turned off manually) → example: dome light or battery fuse.
3. Install an add-a-fuse kit:
   • Insert into the chosen fuse slot.
   • Plug original fuse into lower slot, and a new 2A fuse for the radio in the upper slot.
4. Connect the red wire from the MXT275 harness to the add-a-fuse lead.
5. Secure the black wire to a clean chassis ground (bolt to bare metal).

Option B: Direct to Battery

1. Run wires through the firewall (use a grommet).
2. Connect the red wire directly to the +12V battery terminal.
   • Insert a 2A inline fuse holder within 6–8 inches of the battery connection.
3. Connect the black wire to the negative battery terminal or a chassis ground.
4. Secure wires with loom or zip ties along the run.

Step 4: Antenna Connection

1. Mount your antenna (mag-mount, NMO roof, or fender mount).
2. Route the coax cable into the cab (avoid sharp bends & hot engine parts).
3. Screw the antenna coax into the back of the MXT275 main unit.
4. Run an SWR check for best performance.

Step 5: Final Checks

• Use a multimeter to verify 12V at the red wire and solid ground on black wire.
• Power on the radio.
• Key up briefly (check TX light) and listen for received audio.
• Tidy wiring with loom and zip ties.

Safety Tips

• Never connect red wire without a fuse in line.
• Don’t ground to painted or rusty metal—scrape to bare metal.
• Keep wires away from pedals, sharp edges, or moving parts.