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On Feb 12, 5:17 pm, "KE5MBX" wrote:
Hi, What's all this business I hear people talking about blasting people's car stereos or killing cars altogether with high-power RF? Seems reasonable that high intensity RF could incapacitate the modern electronics that control your average car these days. Put enough RF at the right frequency in the right place and you can disrupt just about anything. I'd bet that the stories are based somewhat in truth. However, the question of "how much" would it take would not be easy to answer. I've heard that 2 meter communications at reasonable power levels would cause specific models to stop running, but I've not seen it myself. I suppose that it would be likely that high power communications could draw too much current and cause the battery voltage to dip below minimum levels required to keep the car running (with a week battery and low alternator output) and folks could be confused as to what actually happened... But we are talking theory.... I currently can run just south of 50W on 2 Meters in my 93 Jeep grand Cherokee and only rarely have issues with the audio system. I can desense the receiver when transmitting at high power, but that is not surprising as the two antennas are about 2 foot apart and run parallel for most of the 2M antenna. I cannot imagine how much RF I'm pushing into the poor car's stereo. I've had no permanent damage to the stereo. I can usually drop back to 5 watts and keep talking w/o any issues so I assume I'm not causing others issues. The car keeps running (well as best as can be expected for something with 160K miles) on either power setting. I've also put this setup in a 2001 Ford Expedition and have had no issues with the stereo as of yet, but the antennas in this situation are separated vertically so I would assume the isolation is much better. I'd bet that if you keep your RF field strengths under the FCC specified limits in the cars around you, and your car keeps running, you won't cause anybody else permanente problems. Car designers have to deal with possible situations where RF field strengths are very high (like when you drive past a broadcast transmission tower) so I'm sure they've designed and tested their stuff to make sure it survives these situations. If you stay within the FCC rules on field strengths I'd wager that nothing serious is going to happen to somebody else's car. You may cause yourself issues, but I doubt you will cause any permanent damage. If you do have issues (the car stops running or the stereo makes strange noises when you transmit) there are ways to deal with that stuff and I'd cross that bridge when you get to it. -= Bob =- |
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