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 on land or the water. Whether to find the best fishing spots, need a tow back to shore or you have a medical emergency, most maritime communication is still conducted over the VHF radio.
There are many different varieties of VHF maritime radios, beginning at around $150 for either a stationary radio (antenna is an extra cost) or a handheld VHF with a built-in antenna. Additional features, such as AIS, remote microphones and color displays can increase the costs to over $1,000.
This week, 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 Coast Guard has very tall VHF antennas and operates with more power and special technology to send and receive communications over much larger distances than the average boater’s VHF radio.
There are 49 VHF channels authorized by the FCC/USCG and 7 weather channels used by NOAA Weather Radio. Each channel is assigned a unique frequency between 156 and 162 MHz.
In order for your VHF to send and receive properly, the radio needs a good source of electricity 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 M506’s rated output 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. There are different types of coax cables available and the type of cable should be upgraded for longer runs due to potential the signal loss. As an example, the high performance RG-8X coax cable is 20% better in dB (power) than the typical RG-58.
The higher the VHF antenna is mounted on the boat, the longer the range of your transmission and reception. Since VHF radio waves travel in a mostly straight line, if your antenna can “see” the other antenna then 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 distant VHF radio, otherwise you may not have much, if any, power radiated in other directions.
The connections (or splices) in the VHF coax wire can dramatically reduce the power getting to your antenna. A single splice 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.
Testing – while there are a few tests a boater can conduct, the first and easiest one 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 and you should listen to see if their signal is 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 automated radio check service. To use this service, tune to the designated VHF channel 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.
If you think you have a VHF problem, you should contract a professional technician who can test your VHF radio and antenna systems using specialized equipment. They can, at a minimum, determine the output power of your radio in watts and check your and 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 radiotelephone (whether voluntarily or required to) must maintain a watch on channel 16 (156.800 MHz) whenever the radiotelephone is not being used to communicate”. This is one of the reasons many boater have two VHF radios. They leave one on channel 16 and use the other radio for recreational broadcasts.
Years ago, every boat needed a license for a VHF radio. Now, most recreational or pleasure craft do not need a license for the VHF radio. An FCC Ship Station Radio License is only required for vessels traveling outside U.S. waters or that meet one of the following requirements:
•Inspected vessels certified to carry more than 6 passengers
•Vessels over 65.6-feet in length
•More than 100 gross tons and certified to carry at least one passenger
•Tow boats of more than 7.8 meters in length
•Uninspected commercial fishing industry vessels required to carry a VHF
•Ships required to carry an Automatic Identification System (AIS) transceiver
•Over 300 gross tons navigating in the open sea
Additionally, if you travel to a foreign port, you are required to have an operator permit.While there is more VHF information that 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 it’s best, allowing you to contact your fishing buddies or communicate with rescue authorities.
Capt. 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.
