Batteries, Power Supplies, Antennas and Basic Fault-Finding
What the exam tests here
Practical reliability: reserve power capacity, battery care, antenna installation, and the first checks an operator makes before calling a technician.
Reserve source of energy
SOLAS IV/13 requires a reserve source of energy, independent of the ship's main power, capable of operating the radio installation for at least 1 hour where an emergency generator is fitted and 6 hours where it is not. It must supply the distress and safety functions - VHF, MF/HF or Inmarsat as fitted - and the emergency lighting needed to operate them. Batteries must be kept charged, checked regularly, and given a capacity test at intervals under the ship's planned maintenance system.
Battery care
Lead-acid cells are checked by specific gravity and electrolyte level; top up with distilled water only, never acid. Keep the compartment ventilated, since charging gives off hydrogen, and keep flames and sparks away. Never short the terminals. Record checks in the battery maintenance log.
Antennas
VHF antennas are vertical whips requiring a ground plane and a clear view; MF/HF whips are 8-10 m with an automatic antenna tuner, and their insulators must never be painted or covered, because paint and salt create leakage paths. Keep antennas clear of radar beams and metal structures, and check coaxial connectors for corrosion and water ingress.
First-line fault-finding
- No transmit: check the power switch, fuse, handset PTT and the antenna/coax; high VSWR suggests a coax or antenna fault.
- No receive: check squelch, volume, speaker/handset selection, then the antenna.
- DSC will not transmit: check Ch70 antenna and coax, MMSI programming and the power supply.
- Inmarsat-C not logged in: check antenna view, ocean region and GPS feed.
Worked example
VHF transmission is weak and intermittent. The operator checks the antenna: the whip base shows green corrosion and the coax connector is loose. Cleaning and re-seating the connector restores range, and the fault is logged. A transmitter fault would have been the wrong first conclusion.
Traps
- Using the engine-start battery as reserve radio power.
- Topping up with tap water or acid.
- Painting over an HF insulator or tying the antenna back with wire.