How To - Mobile Installation - G7SYW's amateur radio bits & bobs...

How To – Mobile Installation

| Posted in Technical Topics

Some careful considerations are required to install a mobile transceiver into a vehicle. This example shows how I installed my Yaesu FT-7800 dual band radio.

Below is a list of a few things you should think about before simply throwing the radio into the vehicle.

Getting power to the radio

Possibly the most important consideration is the power source. A quick glance around inside the car and there is the most convenient power source.

STOP, don’t even think about using the cigarette lighter socket, or aux power socket as they are now commonly labelled.
Why not? There are a variety of reasons why you shouldn’t use this handy, already available source.

Probably the most important reason is the current requirement. It is highly unlikely that the socket or it’s wiring can handle the current needed during transmission.

Virtually all modern vehicles use the CAN bus system. This system is basically a computer network using the vehicle’s wiring which allows the various ECU’s “talk” to each other.

As a consequence, the radio can pick up unwanted noise through this power source. Of course, it’s also possible that the radio could introduce noise into the wiring, thus disrupting CAN bus communication.

Where should we get the power from? The manual that comes with the radio will most probably advise that connections are made directly to the battery.

In fact, every manual I’ve read to date does recommend this method including the manual for the Yaesu FT-7800.

Choice of mobile antenna mount

What’s the best method of mounting my antenna? You may as well ask “how long is a piece of wire?”

Many factors affect the choice and method of mobile antenna mounting.

The magnetic based (mag-mount) may be the best option for some. While others may prefer to drill a hole and mount it directly to the bodywork.

Alternatives include rail mounts, possibly one of the preferred options if your car has roof bars.
The drawback with this method is you MUST ensure the rails are well grounded!

Hatch Mount Another option worth considering is the boot mount or hatch mount.

Both of these clamp onto the lip of the boot lid or tailgate.
They are very similar in design to each other, the major difference being the hatch mount tends to have a greater degree of adjustment.

This is to take the steeper angles often found on a tailgate into consideration.

Gutter mounts are available, again these are similar to the boot and hatch mounts, although these are seldom seen as most modern cars no longer have gutters.

My best option was to use a hatch mount. The reasons for my choice were twofold, firstly, the car is a hatchback, secondly and most importantly, I did not want to drill any holes or damage the bodywork.

The coaxial cable is routed upwards to the top edge of the tailgate, some slack has been left to allow opening and closing of the tailgate.
The coax then follows the line of the boot rubber to the bottom of the aperture. At this point a drip loop is made thus preventing water ingress, before entering at the bottom edge of the boot.

Self adhesive cable tie anchors and cable ties prevent the coax from moving around, consequently, this prevent the cable becoming trapped, damaged or crushed.

Mounting the Yaesu FT-7800

FT-7800 Mobile The ability to use the front panel remotely from the main body was a main consideration for my installation.

A complete kit (YSK 7800 separation kit) allowing mounting of the front panel away from the radio body may be purchased.
Included in the kit are a mounting plate for the front panel along with two cables. One cable connects the front panel to the main unit, the other allows use of an extension speaker.

I already possessed the main interconnecting cable, an extension speaker cable is a 5 minute job to construct, and my mounting location doesn’t require the extra bracket, thus the kit wasn’t required.

The center console coin tray being just slightly larger than the radio’s front panel makes the perfect position to house the head. Small pieces of non-slip foam prevent any movement of the head.