Home Uncategorized On the Radio: Si-Tex MDA-4 VHF Radio

On the Radio: Si-Tex MDA-4 VHF Radio

by Norris Comer
Si-Tex MDA-4 VHF Radio

Pictured left is the standard Si-Text MDA-4 VHF Radio. Not pictured are the two accessories: the GNSS 66 Channel GPS Smart Antenna and Remote Command Microphone Bundle.


Externally, modern VHF radios look similar to their ancestors of decades’ past. However, the VHF radios we see today are jam-packed with multi-use systems inside their humble black or white housings. Enter the new Si-Tex MDA-4 VHF Radio, an affordable unit that essentially combines a VHF-FM/DSC radiotelephone with a dual channel AIS receiver, that is loaded with features from a foghorn to GPS.

At a glance, the black MDA-4 looks both compact and rugged with the numbers to back it up. With modest dimensions of 8.5” (length) x 5.25” (width) x 2.25” (height) with the mounting bracket, the unit could easily fit inside the hypothetical breadbox. The MDA-4 has earned numerous ratings for ruggedness, including MIL-STD-810G (a military spec for ruggedness that tests many factors ranging from salt fog to immersion). A LCD display screen is a nice touch and makes scrolling through options or displaying AIS data easy. Nothing flashy here, but very pragmatic and certainly not a design to be taken for granted.

The brain and the guts of the MDA-4 is where things start to get interesting. Equal parts radio and AIS receiver, the device is meant to be a communications workhorse and primary navigational resource aboard. On the VHF side, it features a wired handheld channel up/down and power high/low microphone with long cord and channel 16/9 quick access button. The device is compatible with all USA, Canada, and international channels as well as private channels. The RF (radio frequency) output power of 25W is on par with other similar radios out there in the professional and commercial sphere (like the also new Icom M605). The 25W foghorn could also come in handy around these parts and a distress signal is available, all good for safety.

But the radio is just the beginning, for the dual channel AIS receiver is what really puts this unit on the map. The AIS complements the VHF nicely because the user can receive information about other AIS using ships (name, heading, coordinates, etc.) via the AIS and then hail the vessels with the VHF as needed. The next step is to somehow get an AIS transponder into the unit, for that would allow the skipper to make direct calls to other AIS users and also broadcast his or her own position via AIS. However, receiving AIS is far better than nothing, and not standard in a VHF by any means.

The MDA-4 is further amplified by NMEA2000 and NMEA0183 connectivity. For those of us with an integrated NMEA system on board, this feature will allow you to fully integrate the MDA-4 into your boat’s suite of systems. In other words, that AIS data from the MDA-4 will be able to be displayed on your compatible multifunction display and overlaid on your digital charts, for example.

The optional accessories add even more capabilities. The full-function remote command microphone will be popular for those who want to do it all from the wheel and is essentially a long-cord handheld microphone but with all the control buttons in the palm of the user’s hand. The GNSS 66 Channel GPS Smart Antenna is a no-brainer, as it brings GPS to the unit. Although installing it is no problem (simply plug in the tiny black box and you’re set), this does seem like the kind of accessory that should be integrated into the housing of the MDA-4 as standard. Nonetheless, it’s there and useful if you want to display your GPS coordinates on the LCD screen or across your NMEA systems.

All in all, the new Si-Tex MDA-4 VHF Radio looks like a great option for boaters of all stripes on the market for a VHF-AIS combination unit with plenty of nice bonuses. The price is great too, with a MSRP of $459 for the base device. The Remote Command Microphone Bundle accessory is $119.95 and the GNSS 66 Channel GPS Smart Antenna is $59.95. You can learn more or search for a local dealer at si-tex.com.

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