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N9OGL: Exceeding the Part 15 EM limitation because that general written was a bitch!
Stagger Lee wrote: On 15 Aug 2006 10:32:49 -0700, N9OGL wrote: Steve the Electrical Field emission for 13 Mhz is 15,484 uV/m @ 30 Meters. Omega One Radio is running a power output 100 watts, and the electrical field emission a 17.5 meters is 2,000 uV. At 30 Meters the field emissions is 0 uV You Also have to remeber that 13 MHz is the 22 meter Shortwave Band, which does skip. It it possible to hear part 15 stations on that frequency. You can put out a higher power and produce the required electrical field. A back of the envelope calculation says you are way over the legal field strength if you're running 100 watts. You can calculate the power it takes for an isotropic radiator to produce a field strength of 15,484E-6 volts/meter as follows: 1. The area of a sphere of radius r is 4*Pi*r^2. An isotropic radiator emitting P watts at the center of the sphere will produce a power density of Pd = P / ( 4*Pi*r^2) on its surface. 2. The power density is related to the electric field and the impedance of free space (120*Pi) by the formula Pd = e^2 / (120*Pi). 3. Solving (1) and (2) for the power, P, you come up with P = (er)^2 / 30. So, for an "e" of 15,484E-6 and an "r" of 30, P = 0.00719 watts, or roughly seven milliwatts. Since antennas are not isotropic, the power must be reduced even further so that the electric field will not exceed the legal limit in the direction of highest antenna gain. This calculation ignores line losses and final amplifier inefficiencies, but there's no way in Glendale you can convince me that you can take a 100 watt transmitter and manage to lose so much power that you have seven milliwatts or less being radiated. All my DeVry Correspondence School instincts tell me that you are seriously in violation of the law. Other DeVry grads at the FCC will immediately agree, as will our distinguished alumnus, KC8JBO, the only man to have discovered negative VSWR. Be careful, Todd, and rethink your current station configuration. ==================== "lean how to spell it write, moron" -- N9OGL in message .com poor little toad........couldn't get past general now the mean hammies won't let him play radio! BWHAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!!!!!!!!!!!! |
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