Marine PC's & WIFI by IslandTime PC
Installation Considerations
System Block Diagram
SystemBlockDiagram.jpg
The diagram right shows a typical system layout.  Click on the diagram to see it full size.
 
The hardest and most important decision in an installation is the location of the antenna.  A good location will provide a 360° view of the horizon and be on or near the case to minimize signal losses in coax.
 
On a sailboat the obvious choices are any structure on the stern that will allow the base of the antenna to be 6-8 feet above the deck or the masthead.  On a power boat a location similar to the VHF antenna will usually do.
 
If you want a masthead installation without the added weight of the die-cast aluminum case at the masthead, we recommend the addition of a bi-directional amplifier to make up for the losses in the coax run.  We can install a 1 watt amplifier in the case for $180.  Contact us for more information.
 
Ideally you will mount the antenna directly to the case, eliminating all coax.  If you have to mount the antenna remotely from the case try to minimize the distance seperating them and use a high quality coax; 400 series coax for runs up to 25 feet. If you need a smaller diameter coax for installation reasons, use 240 series coax and try to keep the run under 10 feet.
 
IslandTime can provide low loss, white, 400 series or 240 series coax terminated with N-Male fittings for $18 for 3 feet and $1.25 per foot for additional footage.

LMR400 has a loss of 6.6db per 100 feet and 12.6db for LMR240 and every 3db of loss equals about a 50% drop in output power or received signal.

In marine applications with long distances between the AP and your vessel, all loss is important so plan your system to minimize the losses.  Keep your coax run short.

Attenuation Calculator

You can use the Attenuation Calculator to find the loss in a wide variety of coaxial cables.

LMR400_Losses.jpg

IslandTime PC * 2641 Park Lane Ct. E. Unit F * Birmingham, AL* US * 35223