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#1
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That's the most compelling argument I've seen to explain this...when Ron
mentioned that the modulation was in the Q channel, you had to know that it wasn't coming from conventional amplitude modulation. Here's my recording of the "WFAN hum", as received today on a battery-powered Sony SRF-A100 receiver in wideband AM Stereo mode: ftp://ftp.amstereoradio.com/uploads/wfan-hum.mp3 This was received in C-Quam-compatible mode, but switching to ISB (Kahn) mode yielded no audible difference. A spectrum analysis of the L-R component reveals it to be a 120 Hz hum with multiple harmonics extending well above 1 kHz... so it's more of a "dirty" hum, akin to that of an audio device with inadequate filtering of its DC power supply. |
#2
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Yeah, that's what my ears tell me, too....it's not a ground loop, in my
opinion...sounds just like the buzz I get when I plug a DC-powered radio into a battery eliminator, before the eliminator's loosely-coupled transformer-powered DC supply's come up to full filtering. The only other thing I could think it is (which you've pretty much eliminated when you said you see it even in the midst of a power failure (I assume that was in August?) is that I've seen it where the AC line can get intermodulated somehow with a station, which is localized around only one station or so. Even that, however, is amplitude modulation, so it's doublenixed as a possible explanation. -- For direct replies, take out the contents between the hyphens. -Really!- "WBRW" wrote in message om... That's the most compelling argument I've seen to explain this...when Ron mentioned that the modulation was in the Q channel, you had to know that it wasn't coming from conventional amplitude modulation. Here's my recording of the "WFAN hum", as received today on a battery-powered Sony SRF-A100 receiver in wideband AM Stereo mode: ftp://ftp.amstereoradio.com/uploads/wfan-hum.mp3 This was received in C-Quam-compatible mode, but switching to ISB (Kahn) mode yielded no audible difference. A spectrum analysis of the L-R component reveals it to be a 120 Hz hum with multiple harmonics extending well above 1 kHz... so it's more of a "dirty" hum, akin to that of an audio device with inadequate filtering of its DC power supply. |
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