| How to Select a Fixed Mount VHF Radio What They Do
VHF (Very High Frequency) radios
provide two-way communications with a range of 5 to 25 miles. They are, arguably, the most
important safety item on board a boat. In coastal or inland waters, a VHF radio is
generally the fastest link to rescuing agencies like the Coast Guard, a towing service, or
the harbormaster. Other uses include: conversation with other boaters, weather
information, harbor communications, lock and bridge tenders, and race committees.
How They
Work
Unlike Single Sideband or shortwave radios, VHF radios transmit and
receive line of sight signals. That is, mountains, land masses, the curvature of
the Earth, or anything else that limits your ability to see in a straight line will also
block VHF signals. VHF radios only listen to the strongest signal they receive. If several
boaters are transmitting simultaneously on the same frequency, you will only hear the one
with the strongest signal.
Fixed-mount radios are legally limited to 25 watts of
transmit power. All radios have the option of transmitting at 1 watt of power so that
short-range conversations are less likely to interfere with large numbers of boaters. It
is an excellent idea to try to reach your party on 1 watt before switching to 25 watts.
Your antenna installation is the most important variable
affecting the operating range of your VHF. Mount your antenna as high as possible: on the
mast of a sailboat, or on the superstructure of a powerboat. Use an antenna with 6 or 9 dB
gain on powerboats and 3 dB gain on sailboats. Use large-diameter, low-loss coax
cable with properly installed connectors and run it as directly as possible to the radio.
It used to be that radios varied in the number of channels
that they offered. This has now changed, and every fixed-mount VHF radio we sell has all
the operational U.S., International and weather channels pre-programmed. Likewise, the
receiver sensitivity and selectivity of all the VHFs we offer are so close that they
simply aren't an important differentiating factor.
What to
Look For
Channel Selection
Two systems are used in modern VHF radios:
Rotary Knob-A dial is twisted
until the desired channel is reached. We generally prefer this type for fastest access.
Keypad-Two keys, one for UP
and one for DOWN, enable you to select the channel you want. Some radios now have channel
selector buttons on the microphone as well as on the radio itself. We like the convenience
of this feature. All VHF sets have a special button that immediately selects emergency
Channel 16.
Priority Scan places priority
on Channel 16 so emergency communications and hailing calls will over-ride other traffic
on other channels. This works if the congestion on Channel 16 is light, but can cause the
radio to "listen" to Channel 16 most of the time in high-traffic areas.
Dual Watch scans Channel 16
and one other channel of your choice. It is handy when you want to monitor 16 for incoming
calls to your vessel, but also want to listen to fishing chatter, vessel traffic or a race
committee on another channel.
Tri Watch-Monitors Channel 16
and two other channels. Now that the Coast Guard is changing the hailing frequency to
Channel 9 in some areas, and has reserved Channel 16 for emergency traffic, Tri-Watch
allows boaters to monitor Channel 9 for hailing, Channel 16 for emergency broadcasts, and
one additional working channel..
Weather Alert
Also known as Weather Watch, this function enables the radio to signal you when there
is an urgent NOAA weather broadcast. When the radio detects a special warning signal from
NOAA, it sounds a special tone. On some radios (Raytheon) the radio automatically tunes
itself to the active weather channel so you can hear the broadcast. On Standard
Communications and Shakespeare radios, you must manually tune the radio to the weather
channel.
Audio Output
This number indicates the loudness with which you can hear incoming broadcasts. This
is especially important if you need to hear over lots of engine noise. We strongly urge
you to consider the use of an auxiliary speaker. The fidelity is considerably better than
the silver dollar-size speakers built into most radios.
Weather Resistance
If your radio will be mounted in an exposed location, its ability to withstand water,
extreme temperatures, and UV rays are critical. Our best advice is to base your selection
on the reputation of the radio for waterproofness, and to have a handheld in reserve.
Microphones are continuing to
get more complex, with some offering all the functions that are found on the base radio.
Standard's Intrepid, for example, can use the RAM Microphone, which provides full function
remote capability. Change channels, change volume levels, add or delete channels from the
scanner's memory: all are possible from the keypad included with the RAM Microphone. This
is obviously more than a complicated microphone-it's actually a entirely separate station
for your radio which is ideally suited for the flying bridge, tuna tower, navigation
station, cockpit, or wherever you could use VHF communications. |
