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"Steve Lusardi" wrote in news:gaf992$2tl$01$1
@news.t-online.com: Larry, Why would this antenna's radiation not be coupled to ground, as it is so close and in parallel alignment with the grounded stay? Steve By the way, the most powerful AM radio stations in America run 50,000 watt blowtorch transmitters that USED to be HUGE and use amazing amounts of power, converting most of it into heat for the cooling ponds in the yard. Today's 50,000 watt transmitters are made by Harris. Instead of huge tubes and city-sized power supplies, they use 48 of these tiny transistor modules: http://www.hawkins.pair.com/wabcnow/wabcn14.jpg Notice the US quarter dollar coin to show the size of them. The modules are digitally switched on and off by the audio waveform fed to a control circuit and are over 95% efficient, like the switching power supply in your desktop computer. To put 50,000 watts of serious RF power on the antenna, one only needs 55,000 watts....not 130,000 to 180,000 watts of the old transmitters...from the greedy power company. The transmitter is actually cooled with muffin fans like the one on the back of your computer. The old transmitters had huge air blowers or distilled water cooling systems to take away the awful waste heat. Any US stations you hear in Germany have this transmitter, now.... Amazing technology.... These white fuses are just like the ones in your radios....nothing special. If a module fails, the red light lights up, the control computer ignores it until the technician reaches into the OPERATING high power transmitter and pulls out the bad module while it all stays on the air and replaces it. Noone in their cars will ever hear it fail. That module in the picture has 8 transistors (the little black tabs with one screw on the copper heat sinks. It, by itself, puts out 1,500 WATTS of RF power.... The cooling air blows through the little holes in the copper heat sink... They run 500,000 hours between failures! Not very impressive unless you're standing at the base of the tower listening to the hissing of the high RF power across the massive insulator: http://www.hawkins.pair.com/wcbs_wfan/cbsfan_twr14.jpg BOTH WCBS and WFAN in New York City transmit on 660 Khz and 880 Khz through that little piece of copper tubing coming out of the tuning house using some trickery of inductance and capacitance I tried to give you a glimpse of earlier: |
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