Operating the LPX-14 DuraComm® Power Supply

The LPX-14 DuraComm power supply allows operators to use their Midland MXT radios with standard AC power, making it ideal for base station setups or indoor use. It provides a stable 13.8V DC output—similar to a vehicle’s electrical system—ensuring reliable performance and full transmit power. Compact, efficient, and easy to wire, the LPX-14 offers a dependable way to run MXT radios without relying on a 12V battery or vehicle connection.

Connecting the MXT to the DuraComm:

1. Power Supply Wiring (LPX-14):

• Connect the LPX-14 to AC mains (90-264 VAC input).
• Ensure the +V (positive) and -V (negative) DC output terminals are accessible.
• Turn the LPX-14’s switch ON after all wiring is secured and check that the indicator LED lights up.
• Make sure the unit has adequate ventilation and is not in an enclosed hot space.

2. Radio Connection (MXT275):

• If your MXT power cord has a cigarette-lighter plug or O-rings, cut off the plug or rings to allow connection to the LPX-14.
• Strip about ¼ inch of insulation from the red (positive) and black (negative) wires of the radio’s power lead.
• Insert the red wire into the LPX-14’s +V terminal; insert the black wire into the -V terminal. Ensure no bare wire is exposed.
• After making connections, plug the radio’s microphone and antenna cable as per the MXT275 manual.

3. Antenna & Grounding:

• Mount the antenna in a high, open location with a good metal ground plane for optimal range.
• Run coax cable cleanly, avoiding sharp bends, high-heat areas, or running alongside other electronic power wires.
• Ground the radio chassis and antenna mount to the same reference if in a vehicle or to a common earth ground if in a base station.

4. Double-Check & Test:

• Verify polarity: Positive to positive, negative to negative. Reversed poles can damage equipment.
• Turn on the LPX-14, then power up the MXT. Observe that the radio powers up properly, the display activates, and no error/fault lights appear.
• Transmit a short test and check that the radio is operating at intended power and that SWR is acceptable.

5. Operational Tips:

• The LPX-14’s DC output can be adjusted between ~11.5 V and 15 V DC. Keep it around ~13.8 V for best performance with the MXT.
• Because the LPX-14 is a regulated supply with low ripple and noise, it helps reduce interference and ensures consistent power, compared to a vehicle’s 12 V system.
• If running multiple radios or other 12 V devices, ensure the total current draw does not exceed the LPX-14’s 14 A rating. Allow margin for peaks.