Q: I’m installing a new AIS transceiver, and it has a built-in antenna splitter. How can I attach my AIS receiver, VHF radio, and FM stereo to the antenna?
A: Built-in antenna signal splitters invariably introduce some signal loss. So far, most manufacturers don’t specify how much, but one I talked with suggests that it’s “about 2 dB,” and that’s a lot. So since your VHF is your primary piece of safety equipment, you should connect a dedicated antenna to it, ensuring that it has the best possible send and receive distances. Connect a second antenna to an AIS splitter (right) and use the output to feed your stereo. One advantage of this arrangement is that you will have a functional spare onboard. In an emergency if the antenna connected to your VHF doesn’t work, unplug the antenna from your AIS and plug it into your VHF.
Q: My fishfinder display is 30 feet from my transducer and my transducer cable is only 20 feet. Can I splice on another ten feet?
A: No. Since the signal from the fishfinder to the transducer contains high voltage there are safety and reliability issues with splicing. Instead, you should use a manufacturer-supplied extender cable. Don’t let your installer change your mind; even a great splice will eventually have issues in a high-voltage marine environment.
This article originally appeared in the March 2009 issue of Power & Motoryacht magazine.