Ray jefferson 5000m marine radio
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Obviously, the larger the value, the better the receiver. The receiver volume is increased gradually until a 10% distortion level is reached and, at this point, the power output is measured.
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As more filters (or better quality filters) are added to a radio, the price must increase.Īudio Output Power is a test of the continuous electrical output power rating of the receiver, as measured across a resistance equivalent to the loudspeaker impedance. Although the fact that the inexpensive unit didn't meet the EIA standards was a surprise, the superior performance of the more expensive Icom was expected by electronics experts, who point out that selectivity is primarily obtained by intermediate filters. The EIA requires a minimum of 70 db and the Ray Jeff was below this standard with a selectivity of 68 db (although this should be adequate to do the job), while the Icom was well above the minimum at 79 db. For reasons best left to the electronic gurus, this is measured in negative decibels and the larger the number, the better the selectivity. This measures the ability of your VHF radio to screen out police and taxi calls on nearby channels.
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Selectivity is also called "adjacent channel rejection," and is a measure of the receiver's ability to differentiate between desired and undesired signals. As one industry expert noted, "External man-made industrial noise will almost always be the limiting factor in the reception of weak signals." In the IF bandwidth used by the VHF-FM radios, the noise of the Milky Way galaxy can account for. This was the only test where the Ray Jeff was superior to the Icom, but it should be pointed out that modern radios, including the two tested, have exceeded the useful sensitivity range because the antenna will collect more outside noise than that level. 5 microvolt or less.īoth the radios easily met the EIA standard, with the Ray Jeff at. The smaller the number, the more sensitive the receiver, and the EIA requires. The sensitivity of a receiver is the minimum input signal at the antenna, measured in microvolts, that will cause the background noise to be reduced by 12 decibels. Sensitivity is a measure of weak signal reception and, although often used as a method of comparing VHF radios, is not a complete or adequate measure by itself, since sensitivity is affected in the real world by outside factors. Let's look at the individual tests to see what they actually proved. We also had both units subjected to the range of conditions that they might meet in the marine environment, testing them at three different temperature and humidity ranges, as well as subjecting them to vibration in three different planes. The receiver tests included sensitivity, selectivity, frequency accuracy, audio output, speaker impedance and acoustic output. Transmitter tests were performed to determine frequency stability, RF output power in both high and low modes at normal and low battery voltage, current drain at high and low transmitting power, and standby current drain. While there are other tests that could be performed ad infinitum, the tests we chose should give the potential buyer some basic guidelines for comparing VHF radios. The Ray Jefferson 5000M and the Icom M120 were selected.īoth the receiver and transmitter functions of the radios were subjected to testing under carefully monitored conditions, and the results were then compared to the standards set by the Federal Communications Commission, Electronics Industry Association and other accepted norms as well as to the specifications found in the advertising brochures for each radio. It provides contact with other boats and land stations, weather information and, in a crisis, it can become your lifeline.īut how do you choose a VHF radio when they range from one hundred to over one thousand dollars in price while claiming to offer essentially the same quality? To see what the differences really are, we acquired two radios over-the-counter and delivered them to the Advanced Product Evaluation Laboratory in Bethel, CT, for testing. No piece of electronic equipment is more important to the average boat owner than the VHF radio.