Garmin VHF Radio Troubleshooting

Garmin VHF Radio not displaying latitude and longitude

If the VHF radio does not display latitude and longitude, check connections and settings. The steps below are helpful for new installations and systems that have stopped working. 

Check Connections

• Check the NMEA 0183 wire. Verify that the wiring connections are secure, match the corresponding wire, and are correctly grounded

• For NMEA 2000, check the NMEA 2000 Device List; what displays as connected? See NMEA 2000 Troubleshooting

Port Types

On Garmin chartplotters set the NMEA 0183 Port Types to NMEA STD for 4800 baud rates or NMEA High Speed for 38400 baud rates. Correct Port type settings are an essential step for third-party VHF radios.

VHF Radio is not receiving or is not transmitting

If the VHF radio is not receiving or transmitting, perform a radio check and check if the weather channel works.

Perform a radio check - how far or near is it receiving and the distance it is transmitting? If the weather channel receives reports but outgoing transmissions are not working, check the following:

• VHF antenna could be faulty 

• Coaxial cables and coaxial connectors 

• Power settings 

• Obstacles blocking the line of sight

Coaxial Cables and Connector Troubleshooting

Length and type of coax cable matter; do not mix different coax cables, do not splice other types or sizes of coaxial cables together, and replace with a complete length of the same coaxial cable. 

Minimize the junctions or splitters connections. There is a .5db loss per junction or splitter connection. Use the correct junction with the matching coaxial cable type. Using mismatched components increases impedance, resulting in signal loss. Select the same impendence throughout the coaxial network. Mismatched coaxial impendence of 50ohm or 75ohm will result in signal loss and transmission degradation. On the cable, look for:

• Pinched cable

• 90-degree bends

• Visible damage to the cord - for example, frays, cracks, cuts, pinched 

BNC, PL- 259, TNC, N, and F connectors should not be mismatched.                                             

The VHF Antennas should not be damaged. If any of the concerns listed above are present, check the following:

• Check for shorts using a voltmeter

• Check Voltage Standing Wave Ratio (VSWR) with the Standing Wave Ratio (SWR) meter if available

• Use a through-line watt meter, and test the input and output power (watts) to ensure the VHF transmission and reception power is to and from the VHF radio and antenna

• Replace coaxial components as needed

Refer to the VHF Antenna owner's manual for VSWR specifications. VSWR measures how efficiently radio-frequency power transmits from a power source, through a transmission line, into a load (for example, from a power amplifier through a transmission line, to an antenna).