Article by Capt. Steve Katz
Radio Check
Even with today’s modern communications devices - cell phones, satellite phones, Wi-Fi, SPOT and EPIRB’s, the marine VHF radio is still the best way to communicate with others while on the water or on land. Whether you need to find the best fishing spots, get a tow back to shore or need help for a medical emergency, most maritime communication is conducted over the VHF radio.
There are many different varieties of VHF maritime radios, beginning at around $100 for either a stationary radio (antenna extra cost) or a handheld VHF with a built in antenna. Additional features, such as AIS and remote microphones can bring up the costs to over $500.
In this column, we will cover two popular VHF topics - performance and use.
A maritime VHF radio transmits at a maximum of 25 watts, for a maximum range of about 25 miles between boats. A VHF radio signal transmits to the receiver radio by line-of-sight, so the taller the antenna at each location, the farther the range. As many of you know, the United States Coast Guard (USCG) has very tall VHF antenna’s and operates with much more power and special technology to send and receive communications over greater distances than the average boater’s VHF radio and antenna. There are 49 VHF channels authorized by the USCG/FCC and 7 weather channels used by NOAA Weather Radio and each channel is assigned a unique frequency between 156 MHz and 162 MHz.
In order for your VHF to send and receive properly, the radio needs a good source of power and a good antenna system. While a radio may function on a voltage lower than required, the transmitting power output will be reduced and therefore the transmitting range too. As an example, the popular ICOM M504’s rated output of 25 watts is at a supply voltage of 13.8 volts.
The type, length and connections of the coax cable connecting the radio to the antenna can adversely affect the performance of your VHF radio. The type and mounting location of your antenna can also affect the performance of your radio.
There are different types of coax available, generally upgraded for longer runs due to the signal loss in the cable. As an example, the upgraded RG-8X coax has about a 20% loss in signal (dB or decibels) than the common RG-58 coax cable.
As stated earlier, the higher the VHF antenna is mounted on the boat, the longer the range of your transmission and reception. Since marine VHF radio waves travel in a mostly straight line, if your antenna can "see” the other antenna, the radios will be able to send and receive with each other.
Many antennas advertise a “gain" in dB, or effective output power. This is done by focusing the radio waves in a narrow beam, which is great if that narrow beam points to the intended VHF radio, otherwise you may not have much, if any power radiated in other directions.
The terminating connections on the VHF coax wire can dramatically reduce the power getting to your antenna. A single in-line connection in your coax run can reduce your performance by .5dB, so try to avoid having any splices and if needed only one between the radio and the antenna.
While there are a few tests a technician can conduct, the first and easiest test is to use your VHF radio to call and talk to a friend on their VHF radio. They should be a meaningful distance away and you should ask the other party how they hear you. You should listen to see if their signal is heard loud and clear on your radio. This tests both your send and receive functions along with your microphone and speaker. If you can’t get a hold of a friend, you might be able to get a free automated radio check using Sea Tow’s radio check service on VHF channel 26 in the Ocean City area. To use this service, tune to channel 26 and conduct a radio check as you usually would. Upon release of the microphone, the system will replay your transmission, letting you hear how you sound. This service does not seem to be continuously available - but it is worth a try.
You can also test your radio's reception by tuning to different NOAA weather channels. If you are able to receive a distant weather transmission clearly, your antenna, receiver and speaker are probably working properly.
If you even think you have a VHF problem, you should contact a professional technician who can test your VHF radio and antenna systems, and at a minimum, determine the output power of your radio in watts and check your antenna system loss by calculating the VSWR.
Once you are sure you have a good working VHF radio, there are a few guidelines, rules and laws that you may need to be aware of.
The USCG states ”In general, any vessel equipped with a VHF marine radio (whether voluntarily or required to) must maintain a watch on channel 16 (156.800 MHz) whenever the radio is not being used to communicate” . This is one of the reasons many boaters have two VHF radios. They leave one on Channel 16 and the other they use for recreational broadcasts. For those who have not been kept up-to-date, an FCC ship station radio license is no longer required for "any vessel traveling in U.S. waters which uses a VHF marine radio, radar or EPIRB, and which is not required to carry radio equipment".
While there is more VHF information we will discuss in future articles, the information above is a good way to check and test your VHF radio to be sure it is performing at its best, allowing you to contact your fishing buddies or communicate with rescue authorities whenever needed.
Captain Steve Katz is the owner of Steve’s Marine Service and holds NMEA, AMEI and NMEA2000 certificates along with ABYC Master Technician certification and factory training from many manufacturers.
