Ray Sills, very simply, is correct. I know because my senior project was building a wide bandwidth "hi-fi" AM receiver. It had audio response out to 10 kHz and it sounded awesome. My senior advisor came into the room to sign off on the project, and when I finished the demo he simply got up to leave and said, "But you'll never hear out to 10 kHz because all stations cut off at 5 kHz or less." I sat there in disbelief. He waited until the last day to tell me this? "If I can prove to you that stations do indeed transmit wideband audio, will you accept my work?", I asked. "No way can you prove it, because it's not true." This guy could be a real jerk when he wanted to. He gave me an hour. With a six-year college career on the line, I then got on the phone and actually reached the chief engineers of two major radio stations in the Los Angeles area, KFI and KNX. Each of them told me, "Oh, yes, we absolutely transmit out to at least 12 kHz." The chief of KFI even said, "We apply pre-emphasis out to 15 kHz to partially counteract the rolloff in the typical receiver." This was in 1985. I went back to the prof to report the happy news, he didn't even make eye contact with me, just grunted, and gave me a "D" -- barely passing. My college professors were such a joy. Anyway, listen in good health. You may have to search for it, but there's some pretty good audio still remaining in the AM bands. Not sure if it's worth it on noisy shortwave, though. Al W6LX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected]
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