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Note: Although the KXPA100 is not yet available from Elecraft, as of July, 2012, the design team
confirmed it will use the 30A Anderson Power Pole connector, so design accordingly.
When exiting your power cable from the engine compartment, first locate a suitable punch‐out
grommet or seal. Most of these are circular, and vehicle manufacturers leave a few spares for
aftermarket equipment installations. Locations and sizes of these entry grommets vary by vehicle. Your
dealer’s technical staff may be able to assist you in finding an appropriate power entry point. Be sure
and replace the grommet when done (yes, with a hole cut for the cable).
Using existing interior cable raceways is recommended. To access these, you’ll usually need to remove
interior panels. Most raceways are located under the doors, and there is normally enough space left to
lay in your power, antenna, and any control cabling. Use caution when removing panels and don’t lose
any of the retainer hardware. You’ll need it when replacing the panels.
When it comes to your vehicle’s trunk, consider laying in and securing all cables under the liner. Not all
trunks have these, but most do. Since the trunk’s main purpose is for stowage, you probably want to
protect the cables from getting beat up by whatever you toss in there. Use cable ties liberally, especially
when suspending wiring and cables from an understructure or near vertical mounting locations.
Here are a few hints that apply whether you install your KX3 cabling or have someone do it for you:
‐ Use the correct wire gauge (see Table 1 below) and terminations;
‐ Make room for fuse holders at the source end of each power cable run;
o Blade‐style fuses and fuse holders are readily available at auto parts stores and mobile
audio dealers;
o Fuses located under the hood should be housed in waterproof fuse holders;
o All fuses, of any type, should be DC‐rated.
‐ Try to route engine compartment cabling so it can be cable‐tied to the wiring harness [loom];
‐ Where possible, use existing cable raceways;
‐ Avoid radical bends in cables and “crimp points” where the cable jacket can get mashed,
mangled, squeezed, ruptured or exposed to similar indignities;
‐ Allow adequate service loops at cable ends;
Auto Electronics 101: Every circuit that branches from a source should be protected for over‐current.
At a minimum, you should protect your radio branch circuit with a fuse at the battery. Figures 6, 7, and
8 illustrate over‐current protection at multiple locations:
‐ Battery: 40A inline cartridge fuse in waterproof holder (Motorola p/n 9C84277B02);
‐ Two branches from relay: 30A blade fuses in water resistant holders;
‐ West Mountain APP Power Strip: five branches, each protected by a blade fuse.
Wire gauge is an important factor because it determines the loaded terminal voltage at the KX3 and/or
KXPA100. Some typical power cable runs are shown in Table 1, below. The goal is to maintain 13.0VDC
or higher at the load when the engine is running. Voltages may vary lower than shown when the engine
is idle or off, so bigger is better. Use high quality copper‐core power cabling, not monster speaker zip
cord.
