automatic antenna tuner (if one is installed), as
shown in the top illustration on page 179.
Antenna Installation
As mentioned above, the two most common SSB
antenna configurations are the extended whip
antenna and using the standing rigging on a sail-
boat (see illustrations page 180). For a whip
installation, the antenna needs to be at least 23
feet long; for a standing rigging installation, the
antenna is typically 30 to 70 feet long, depending
on the size of the boat (see photos page 181).
This variation in length may seem to con-
tradict the precision of the SSB system and
antennas in general, but by adding an auto-
matic tuner at the base of the antenna (com-
mon on most modern boats), the effective
length is automatically adjusted for the fre-
quencies used in SSB operation. On those rare
installations without automatic (or even man-
ual) tuners, the length of the antenna must be
carefully determined based on the frequencies
the operator wishes to use. In reality, this is an
impractical solution for any boat installation.Safety Issues
Safety is an important consideration as you
plan your SSB antenna installation. Passengers
and crew must be protected against live wires
and high voltage. Keep in mind that when
the SSB is in Transmit mode, the voltage
delivered to the base of the antenna system
can be on the order of 5,000 volts!
Particularly with a backstay antenna, you
must design the installation so that no one can
reach or touch the wire accidentally during a
transmission (whip antennas are typically well
out of the way). At the base of the backstay
rig, the height needs to be at several feet above
arm’s length when standing (as shown in the
photo on page 185).
It really isn’t a problem on the split-backstay
boat shown in the photo because the connection
point for the antenna is at the peak of the triangle,182 marine electronics installation and troubleshooting
well above the deck. On single-backstay rigs, you
can achieve adequate protection by placing Teflon
tubing over the stay, again to a height beyond
arm’s reach while standing.
The cable feed to the attachment point is
mounted on insulated standoffs up the rig to the
point where it turns into the antenna, as shown
in the photo. The cable of choice for this purpose
is GTO-15, which is actually ignition wire, and
its insulating properties are in the 15,000 V
range. Never use coaxial cable for this purpose
because its insulation properties are inadequate.
At the upper end of this rigged antenna, position
the insulator to maintain at least 3 feet of clear-
ance between the live wire section and the mast.
The cost and involved procedure for
installing an SSB antenna in standing rigging is
often one reason boatowners choose extended
whip antennas for their sailboats. Whip antennas
are much simpler to install. All you have to do is
assemble the whip and mount it clear of other
antennas by at least 4 to 10 feet (depending on
the uses of the other antennas; see Table 16-9).
In summary, the considerations for SSB
antenna installation are:- Antenna length (23 feet minimum for a
whip antenna; 30 feet minimum for a
standing rigging antenna). - The antenna counterpoise is critical to the
range of the transceiver (more is better). - Flat copper foil tape is the conductor of
choice to connect the counterpoise. - Position the antenna tuner and coun-
terpoise as close to the base of the
antenna as possible for maximum
effectiveness. - Use only GTO-type cable for the connec-
tion between the antenna and the tuner. - On sailboat installations, make sure
that crew and passengers can’t touch
the active part of the antenna during
transmission.