VHF transmission problem

[Chuck - Raymarine - Moderator]

VHF transmission problem

VHF transmission problems may be caused by a number of items including:

- Radio has been configured to "LOW Power" transmission mode
- low battery level
- poor/corroded radio power leads
- insufficient power wire gauge
- a failure of the VHF antenna
- a failure of VHF antenna cable
- corrosion and/or failure of the antenna's PL-259 connector
- a failure of a antenna splitter (if installed)
- a failure within the VHF radio's transmitter circuitry

Before sending one's VHF radio in for service, one may fault isolate the problem by:
- verifying that the radio has been configured to a channel supporting high power transmission
- fully charging the batteries and afterwards attempting to duplicate the problem while the vessel remains connected to shore power
- inspecting the power connections between the radio and power distribution panel for tight, electrically sound connections which are free of corrosion.
inspecting the power connections between the batteries and the electrical distribution panel for tight, electrically sound connections which are free of corrosion.
- inspecting the guage of wire used for extending the VHF radio power leads and the wires supplying power to the power distribution panel. Information addressing how to select the correct gauge wire is available from the ABYC, NMEA and other sources.
- inspecting the VHF cable for kinks, sharp radius bends, or other signs of damage
- inspecting the antenna's PL-259 connector for sign of corrosion, damage to the center conductor, or poor shield connection
- testing the currently installed VHF antenna using a VSWR meter or testing the VHF radio using another VHF antenna. A good antenna with its cable assembly will have a VSWR between 1.0:1 - 2.0:1.

Note: If the vessel is not already outfitted with second VHF antenna or an emergency VHF antenna, then it is recommended that the vessel be so outfitted for safety purposes.

Should the above listed tests not identify the source of the problem, then the VHF radio should be sent to Raymarine’s Product Repair Center to be bench checked / serviced.

Whereas VHF radios are considered a primary item of boating safety equipment, Raymarine recommends regular inspection and testing of VHF radios by their owners. Raymarine recommends that prior to each journey, the vessel operator perform a routine Ship to Ship or Ship to Shore call to ensure that the vessel's VHF communications system is functioning properly. Vessels equipped with a DSC VHF radio should ensure that the marine electronics system is supplying the VHF radio is being with the vessel's lat/lon coordinates by the marine electronics when testing the VHF communications system.

RAYFAQ#