Article by Capt. Steve Katz
ICOM’s new M506 VHF is loaded with new features
Now that it is finally shipping, I want to review a new product, the ICOM M506 series of VHF radios. It is not often ICOM introduces a new marine VHF radio with these significant advantages over the previous models.
The sinking of the Titanic began a public realization of the necessity and safety of the shipboard marine radio. The US federal government‘s “Radio Act of 1912” required the monitoring of marine radio distress frequencies and the licensing of radio stations. The Titanic’s two-radio officers were able to summon help and save lives by contacting nearby ships from within their Marconi radio room. Marine radios continued to improve over the next 50 years. After WWII the use of marine radios aboard private vessels began to emerge.
ICOM Incorporated began in 1954 in Japan to design and build solid state radios, primarily for the amateur radio industry. ICOM America was founded in 1979 to represent their products in the western hemisphere. Many of you may remember some of the early ICOM marine VHF radios and even have a working vintage unit. With a top quality, long lasting product, it seems it would be a task to re-invent and continue to improve the marine VHF, but ICOM has done it with the M506 series.
The ICOM M506 series is actually five new radio models in a similar chassis. Four of the five models can connect to the ships navigation network with NMEA2000 or NMEA0183. The first model has an AIS (Automatic Identification System) receiver built-in and has the microphone connected on the front of the radio. The second model also has AIS, but has a connection for the microphone on the back of the radio, for use where the microphone is wired remotely. The third and fourth models do not include an AIS receiver and have either a front or rear microphone. The last model has a front microphone and can only connect to the ships navigation equipment with NMEA 0183. Prices of the M506 series begins at $450.
With the integrated AIS receiver, the M506 can show real-time AIS vessel traffic information on the unit’s own display screen or compatible navigation display screens. The AIS target call function allows you to easily set up a DSC (Digital Selective Calling) individual call to any on-screen vessel.
The M506 with a NMEA2000 connection is significant since it allows simple connection for bi-directional communication between the VHF and the ships navigation equipment. The VHF will learn your ships position and that information can be used during an emergency call for help. The VHF can also send DSC data and AIS data to your navigation equipment, plotting the location of the sender’s transmission.
The M506 has a recording feature called “last call recording”. This voice recording function automatically saves the last two minutes of the last incoming call. You can replay the received call, and not miss any incoming calls.
A new 25-watt, two-way hailer system, when connected to an external hailer speaker, allows you to talk to people on the deck or shore from the radio’s microphone and you can hear their reply via the hailer speaker. The RX hailer function allows you to monitor the received audio from the hailer horn. The previous model M504A only had a one-way hailer.
This new radio also has a new, optional remote microphone with numerous buttons that can control the operation of the radio as if you were in front of the main unit. This is great if you want to add a second station without adding a second radio. This remote microphone is called the ICOM CommandMic IV (HM-195).
Standard Horizon, a primary competitor to ICOM also manufactures many models of marine VHF radios. They were the first to incorporate an AIS receiver and on-screen display in a marine VHF. The GX2200 VHF is their current, top-of-the-line model with all the modern features, plus it has an integrated 66-channel GPS receiver, allowing DSC calls and AIS plotting without a connection to other navigation equipment. A lower cost Standard Horizon VHF, GX1700 also has an integrated GPS, allowing stand alone DSC operation, with prices beginning at $230.
Now that we have reviewed the fun part, let’s review the business end of the DSC safety function referenced above. Digital Selective calling, or DSC is a “paging system” that uses digital data signals to automate the transmission and reception of calls on VHF marine radio, using channel 70 to transmit digital data. Every DSC radio needs a unique number to function properly. This number is used when you want to call other radios, just like a mobile phone. However, unlike mobile phones, DSC allows you to call every other radio in range at the same time if you are in trouble. This unique number is called a Maritime Mobile Service Identity (MMSI) number, a nine-digit number that identifies your boat, like a phone number for your boat. This number is free to pleasure boaters in the USA by registering with BoatUS or the United States Power Squadron.
Modern VHF radios (since 1999) have a one-button (red) distress emergency transmit capability that sends out the vessel's MMSI number and, if properly interconnected, the vessel's latitude/longitude position. This DSC distress call will hopefully be received by the USCG with their Rescue 21 system. This Rescue 21 system was created to better locate mariners in distress and save lives and property at sea and on navigable rivers. By harnessing modern technology, Rescue 21 enables the Coast Guard to execute its search and rescue missions with greater agility and efficiency.
Marine VHF radios purchased after March 2011 have a DSC test calling capability. Transmitting a test call (not a routine DSC call) to the MMSI identity 003669999 will trigger an automatic reply from any USCG Rescue 21 station within range. If the radio does not have a test call capability; you can test it by sending a DSC call to another DSC - equipped radio.
An upgraded VHF is a great piece of safety and communication equipment, please be sure to register and program your MMSI number into the new VHF and connect it to your navigation equipment. If you are not installing a new radio, take the time to check your existing radio to be sure your boat’s MMSI number is programmed properly and that the DSC function is operational.
Captain Steve Katz is the owner of Steve's Marine Service and holds NMEA MEI, AMEI, NMEA2000 certificates, ABYC Master Technician certification and factory training from many manufacturers.
