5. Radio Tester
A VHF tester like the Shakespeare ART-3 ($145, shakespeare-marine.com) is a mini version of the equipment used by professional marine electronics technicians to test a radio and antenna. It can be conveniently connected to the antenna cable to let you know if your VHF is in top operating condition every time you depress the transmit button. It provides an instant radio check by indicating transmitted power out, modulation condition and reception quality. It also provides early warning of possible or pending failure.