Icom iM604A Review Manual page 4

raymarine standard horizon
Matrix AIS +
Ray 218
GX2150
$456 $340
3 years limited 3 years
NMEA 0183 NMEA 0183
1,2,3,6,7 1,2,3
Yes
3.84 x 7.79 3.1 x 7.1
x 7.06 inches x 4.8 inches
2 5/8 x 1 3/8 inch 2 7/8 x 1 3/8 inch
No
30 watts 30 watts
Yes
IPX7 IPX7
TEsT rEsULTs
89 decibels 88 decibels
22.8 / .90 watts 23.5 / .81 watts
22.8 / .90 watts 23.2 / .80 watts
3.4 / .6 amps 3.8 / 1.2 amps
3.4 / .6 amps 3.6 / .6 amps
Excellent Excellent
Good Very good
Good Good
Excellent Good
Very good Very good
Receiver
sensitivity was Only unit with
lowest of group built-in AIS; least
but was good and frequency error.
within specs.
practical sailor
e l e c t r o n i c s
ing; and all were capable of supporting
remote "smart" mics. A few even sup-
ported multiple remote mics.
All of the radios had channel scan-
ning features, ranging from standard
$
and custom memory scanning to dual
watch, which monitors channel 16 every
couple of seconds, and tri-watch, which
monitors both 16 and 9. Each radio is
also waterproof to IPX7 (can handle im-
mersion in 3 feet of water for up to 30
minutes) or IPX8 standards (rated for
continuous underwater use), and all can
be interfaced with a GPS.
Yes
One test unit, Standard Horizon's
Matrix GX2150, featured a built-in Au-
tomatic Identification System (AIS) re-
ceiver that displays other boats' AIS data
(including vessel name, speed, course,
etc.) on a radar-like screen.
Yes
Only one test radio, the IC-M604A,
featured an alphanumeric keypad,
which can make entering MMSI con-
Yes
tact numbers and DSC call data faster.
According to Icom Sales Manager David
McLain, fewer than 5 percent of recre-
ational boaters use DSC functions, so an
alphanumeric keypad is not always con-
sidered a must-have feature. VHFs with-
out keypads are also typically cheaper
and require less mounting space; how-
ever, access to a keypad is still a valuable
benefit, in our opinion.
All of the test radios feature automat-
ic fog signals via a hailer, and all have
Class D DSC capabilities and operation,
which means they have one receiver that
monitors voice channels and another
that continuously monitors channel 70
for digital DSC calls. Also, all DSC Class
D radios will make distress, individual,
all ships, and group calls.
As noted in our June mid-priced
VHF test, GPS compatibility and DSC
capability are imperative for a VHF to
serve its intended function: distress no-
tification. Providing the unit with GPS
data and a properly programmed Mar-
itime Mobile Service Identity number
(MMSI) for DSC operation means the
boat can be more easily identified and
located in an emergency.
To make a distress call with a DSC-
equipped VHF, users simply press the
well-marked, red distress button for five
seconds. Once the DSC call is acknowl-
edged, users would then issue a voice
Mayday on VHF channel 16.
Future articles will take a look at
other marine communication products
and accessories, including remote VHF
microphones, handheld VHFs, portable
sat phones, and AIS standalone units.
hoW We tested
Practical Sailor testers ran all the radios
through a series of bench tests—includ-
ing transmitter power output, frequency
accuracy and stability, and receiver sen-
sitivity—using our Ramsey COM3010
service monitor. All radios in our test
group met industry standards with re-
gards to the above tests, but some did it
better than others.
Regulations set by the U.S. Federal
Communications Commission (FCC)
restrict the maximum power output of a
marine VHF transmitter to 25 watts and
specify the need for a low-power setting,
typically 1 watt, for harbor use. Testers
took transmitter power measurements
directly off the VHFs' radio antenna
ports, because in any real-world sce-
nario, factors such as antenna size and
design, connecting cable length and
type, or faulty connections or corrosion
could limit the actual radio frequency
(RF) power emitted from the antenna.
Transmitter power stability was rated
over a range of tests that included vary-
ing the input voltage and radio tempera-
ture. The less variation in power output,
the higher the radio was rated.
Frequency accuracy is the ability of
the transmitter to send out signals on
a selected frequency. Frequency stabil-
ity measures the transmitters' ability to
maintain frequency accuracy. The FCC
mandates an accuracy of 10 parts per
million (about 1550 Hz off frequency).
Industry groups typically call for half
that error.
Each unit was connected to a regulat-
ed power supply using the factory leads
and appropriate crimp-on terminals.
All manufacturer-supplied power leads
contained a fuse holder and fuse. Power
draw was recorded while transmitting at
13.8 and 11.8 volts DC, in both high and
low power modes.
Receiver sensitivity, the ability of the
radio to hear a weak signal, is normally
july 2012 9