Most manufacturers provide excellent installation
instructions and technical support with their HF equipment
. See links at end. Follows some general basic tips that might be useful when planning your SSB installation
Please donít hesitate in posing specific
HF Installation Basics:
1. Install transceiver as close to your operation site and to the power supply system (batteries) as possible.
2. The antenna
must be installed in an open space and as far as possible from your operating point. As an example, on a sailboat, use the backstay as the antenna
, since it is the farthest point away from the rest of the vessel.
3. The antenna coupler must be installed at the base of the antenna.
4. Always create your own ground with radial wire or copper straps. They are the only ones that will guarantee a solid and proper ground system.
5. All cables
- power supply, control or coaxial - must always be as short as possible and/or necessary. Any excess cable should be shortened to the proper length - never coiled.
RF Grounding Basics:
Overall, there are probably as many different ways to create a good RF ground as there are people giving advice about them. What works in one boat may or may not work well in another. Be prepared to adjust your RF grounding as you test it and remember that it will degrade over time, so you also need to be ready to maintain it.
1. Get as much metal into your RF ground as you can. On some boats the engine
, thru-hulls, and even copper plates are connected together into the RF ground.
When anchored (or docked), you can improve your RF Ground by temporarily connecting an overboard
ground plate. Connect a wire from your Tuner Ground Lug to a Fround Plate which is led overboard
and immersed in the water
2. Keep ground straps as short as possible. Connecting to your RF ground can be tricky. Often people will use a Volt-Ohmmeter to check their ground straps and declare them good because there is little or no resistance. However, the ground strap is not for DC current
. An RF ground is carrying RF energy and a DC resistance to ground will not show if there is an impedance to ground at RF frequencies. Be aware that RF conductivity is not the same as DC conductivity.
3. Donít confuse your safety
ground (equipment chassis, reefer, etc) with your RF ground. The RF ground is required for the ANTENNA and is an RF circuit. Your safety
ground on the DC circuits is NOT intended to handle RF. While many boats connect these together successfully, it can cause interference
. RF energy carried through the DC ground may get into instrumentation or other equipment
. It is normally best to have the RF and DC grounds be separate.
4. Dynaplates and other external devices meant to connect your RF ground to seawater can be very effective, but they will only be so if you maintain them properly. If you connect your RF ground to Dynaplates, thru-hulls, and other fittings, then you must inspect them regularly and CLEAN them regularly. Dynaplates should not be left more than 3 months without inspection
5. Inspect your connections regularly. A salt water environment
is hard on any sort of electrical
connections. Your RF ground and your antenna need to be inspected regularly because the tuner will hide slow changes in your antenna or ground system until it can no longer compensate for them. You may operate for a long time as your fittings corrode and then find that you canít operate at all. It will seem sudden, but the problem grows gradually.
6. A useful test of the quality of your ground is to lay out several long wires on deck
connected to the RF ground connection on your tuner. You might also throw a wire over the side to connect to seawater as well. When you remove these temporary wires, reconnect to your boatís grounding system. The signal should get better. If it gets worse, your RF grounding system needs work
7. Bonding a lot of metal in your boat together with short, direct copper straps can create a very suitable grounding system. The engine
and water tanks
, the keel
, and any other piece of metal of significant size can be bonded together effectively. Copper foil or wire is usually best here.
8. Some boat owners install a large area of copper foil on the inside surface or their fiberglass hull
and use this as an RF ground. It capacitively couples to the seawater and makes a generally excellent grounding system.
9. A leaded keel also makes an excellent RF ground. Depending on the construction of the hull
, you may or may not be able to make a good connection to the keel bolts
718 BaseTransceiver Manual: http://icomamerica.com/support/manuals/ic-718.pdf
AH-4 Tuner Manual: http://icomamerica.com/support/manuals/ah-4.pdf
And some further reading:
antenna and grounding considerations:
Sideband Simplified - by Gordon West: