The Uniden UM425 is a mid-priced marine VHF radio with some unique features. They include a basic hailer, battery voltage monitor, and dot matrix screen.
One-button control is available for making a DSC distress call, selecting transmitter power level, hailer, weather channels, menu, and a quick 16 or 9 selection.
Uniden UM425
Two small knobs on the right side of the radio panel turn the unit on or off and set volume and squelch.
Channel selection can be made with up/down arrow keys located on the front panel and microphone. Quick 16 or 9 and tri-watch can also be selected from the microphone.
Basic functions like backlight adjustment, turning key beep on or off, selecting a channel group, choosing dual or tri-watch scanning, and making DSC calls are handled through menus.
If input power to the radio drops below 12.2 volts a low battery warning message displays onscreen accompanied by an aural alarm. When we increased the input voltage back above 13.0 volts the warning terminated. This warning proved to have a few glitches as it come on and stayed on several times when the input voltage was at 13.8 volts.
Performance
We found transmitter power output and frequency accuracy to be stable throughout our range of tests, both earned good ratings. Receiver sensitivity was rated excellent while receiver selectivity is specified by the maker at a very respectable 78 dB. Audio output was average with sound pressure levels measured at 88 dBA.
This Uniden marine VHF radio features a dot matrix display screen. Channel numbers are shown in large block letters on the right side of the screen above a channel comment line. Channel comments are also shown onscreen when making channel changes with the arrow keys.
Transmitter power, channel group, memory scan, and transmit/receive messages are also displayed onscreen. When GPS data is input to the radio date, time, position, course, and speed can be displayed onscreen with the channel number by pressing the select key. We rated the display good.
Scanning
The most basic scan mode monitors a weather channel while operating the radio normally. Every seven seconds the radio will scan the last weather channel selected and check for a weather alert. Dual Watch and Triple scan the selected channel and 16 and/or 9 every two seconds.
Memory scan looks at memory saved channels in numerical order. Dual, Triple, and weather alert can be combined. Scanning options are controlled with menu options and a pair of front panel buttons.
Hailer
The UM425 has a 10-watt hailer, called Public Address in the manual that provides basic voice over a public address horn. The system is operated by pressing and holding the PA button on the radio front panel. This will transition the unit to PA mode and annunciate PA onscreen. Then you use the microphone normally and your voice will come out over a connected hailer horn.
Digital Selective Calling
The UM425 is a Class D radio for DSC operations. That means it has two receivers, one for voice communication channels and another for continuously monitoring channel 70 for any digital DSC information. This radio can transmit and receive distress, individual, all ships, group calls and send and receive position data. It will store up to 20 names and their associated MMSI numbers for making DSC calls as well as 20 received calls.
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Final Thoughts
Overall good performance coupled with a compact size make this Uniden marine VHF a top choice for many boaters.