First off, the batteries of each handheld marine VHF radio we test are fully charged using their associated AC charger.
Then we run each radio through a series of bench tests using a communications service monitor. Our tester records results for transmitter power output, frequency accuracy and stability, and receiver sensitivity.
Normally the maximum power output of any handheld marine VHF radio is limited to 5 watts, though some handhelds now boast output of 6 watts. A low-power setting of 1-watt for harbor use is also available on all radios. In addition to the high- and low-power settings, a few of the radios had a mid-power setting. We test only at maximum power and at the 1-watt setting. We take transmitter power measurements directly off the radio antenna port.
A transmitter test is done on each radio on channel 16. First at room temperature (75 degrees F) and then at temperature extremes near the minimum and maximum temperature capability of each radio.
We also check each handheld marine VHF radio low-power setting, measuring both power output and frequency accuracy. Transmitter power output and frequency stability was rated over the entire range of transmitter testing; the closer a unit holds to the appropriate frequency and the more consistent its power output, the higher it was rated.
To reach the cold extreme, radios are placed in a freezer at 15 degrees F for four hours prior to testing. We used an small environmental chamber to get the radios to the high-temperature extreme. Radios are left to cook for two hours at 122 degrees F and then immediately run through another series of transmitter-power and frequency tests.
Receiver sensitivity is the ability of the receiver section to hear a weak signal. Typical handheld VHF receiver sensitivity ratings run from .22 to .35 microvolts, with industry groups recommending a minimum of .50 microvolts. All the radios we’ve tested did a good job here, meaning they are more than sensitive enough to pick up weak incoming signals.
Another receiver standard is selectivity; it is the ability of the receiver to reproduce only the signals you want to hear and not others, even though they may be strong and nearby. Our test equipment did not allow us to test each radio for this characteristic. Each manufacturer provided selectivity information, a higher number is better.
Audio System Testing
An important part of any handheld marine VHF radio often overlooked is the audio amplifier and speaker. Boats can be noisy places, and if you cant hear the output, it doesnt really matter how well the transmitter or receiver work. To rate the audio system of each radio, we measured the sound pressure at maximum volume while generating a 1 KHz tone with our communications service monitor and inputting the tone into the radio. Measurements were taken in dBA at a distance of 1-foot using a handheld decibel meter. Our tester also listened to each radio by monitoring a weather channel and rating the quality of sound reproduction.
Display screens were rated for the size of the channel number displayed, the amount of other information shown, the value of the channel comments, the size of the screen, and the quality of the backlighting.
Odds and Ends
A submersion test was conducted on each radio to confirm it as waterproof. The tester turned on the radios and submerged them in a bucket of fresh water for 30 minutes. After removal, he checked the radio for proper operation immediately and then again the next day. All passed.
Since these radios are frequently taken on and off the boat, we elected to perform a drop test to confirm radio durability. Each radio was turned on, and then dropped from a height of 4 feet onto concrete. Again all passed.
The clock started ticking for the battery-life test immediately following charging. We allotted the first hour of battery use to run our bench tests. Radios were off during their time in the environmental chambers and then turned back on a couple of days later and allowed to run continuously for the next 14 hours. We accomplished full power transmissions for about three minutes every hour and voice reception for about five minutes every hour until the battery died or the unit began to malfunction. Total battery test time was 15 hours. Radios still fully functional at that time were rated at 15+ hours of battery life.
In the final analysis of each handheld marine VHF radio, we considered performance, cost (initial and battery replacement), warranty (both unit and battery), battery life, included equipment, recharge time, display, and audio output.