I get those too ... good news is that they usually only occur on frequencies where weak rare DX are hiding!
I thought it was discussed previously that this likely a by-product of the switching power supplies in other electronic devices, possibly even those in Flat Panel Monitors, TV's, etc -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Mike WA8BXN Sent: Wednesday, September 08, 2010 1:42 PM To: audio...@charter.net Cc: flexradio@flex-radio.biz Subject: Re: [Flexradio] Drifting noise hills To all: I am several miles from anything close to industrial. Neighborhood noise generators like appliances would not be on for hours. I tuned around with my 1500 now to see what I could find. At the upper end of 20 M I am finding a similar pattern, but this time its much broader (on the order of 20 KHz) and much less amplitude. Again, the panadapter is really needed to find it. The hill is very smoothly shaped. I somewhat consistent feature is an audible ummmm-ahhhhhh cycle about a second long each half (really hard to describe in words). On the panadapter this audible difference is a slight shift in frequency back and forth. Usually there is an overall movement up or down in frequency, that with time can reverse itself. At one point my son had a bit of interest in radio astronomy and I did a bit of reading on listening to Jupiter's moons or something like that. There were some suggested HF frequencies to listen to (mostly picked because of little earth use of them). I wonder if what I am seeing perhaps in part could be space noise? Its been interesting reading all the comments, thanks to all who have contributed. I'm glad others have seen similar things. 73 - Mike WA8BXN -------Original Message------- From: Jim Barber Date: 9/8/2010 1:27:14 PM Cc: flexradio@flex-radio.biz Subject: Re: [Flexradio] Drifting noise hills Variable-frequency motor drives can look like that too. Any industrial Laundries, food processors etc. In the neighborhood? Of course the neighbor's front-loading washing machine could just as Easily have a noisy VFD, (my Sears Kenmore Elite does, unfortunately) But the regular hours of operation would indicate something else. 73, Jim, N7CXI Lynn Willoughby wrote: > I also have, what I believe, you are seeing. Mine start daily (days > week), between 12:15 PM and 1:00 PM CDT. The "hills" rise and fall at > cyclic rates of 4 sec some days, 8 sec other days and occasionally 12 > sec. The hills disappear sometime after 4:00 PM CDT. > > The "hills" are spaced between 15 kHz and 17 kHz across the entire 20 > meter band. They do not appear below 14.0 MHz. The hills rise 15 to 20 > dB above the "normal" noise floor. The hills center at different > frequencies on different days but not specific pattern has been determined > > At my station, if a wall wart was the source it should be there all the > time. If it were the San Antonio International Airport Radar, I should > see it sweep (come and go) at the rotation rate of the antenna. I've > considered RF drying ovens for wood or RF plastic melting machines, > medical equipment, etc. > > I haven't found the source but continue to try to minimize the effects > on my reception. I am interested in any ideas and will watch the > reflector. It is of some comfort to know it is not just me. > > 73, > Lyndon (Lynn) Willoughby, AE5LK > Willoughby & Voss, LLC. > ----- Original Message ----- From: "Mike WA8BXN" <hubb...@hotmail.com> > To: <flexradio@flex-radio.biz> > Sent: Wednesday, September 08, 2010 9:40 AM > Subject: [Flexradio] Drifting noise hills > > >> I have noticed at times (particularly during fox hunts) what I can best >> describe as a noise hill that usually drifts around in frequency. For a >> width of several KHzon the panadapter I see what is shaped like a "normal >> curve" that trails off for many more KHz. In panfall mode I can see a >> brightening where the curve in the panadapter display. >> >> >> >> Sometimes, when the peak of the curve is in the passband of the >> receiver I >> can hear a shift in the noise frequency at around a second or two >> intervals >> as the peak drifts around. >> >> >> >> I have observed this with both a 1000 and 1500 flex radios. Disconnecting >> the antenna gives a flat display. Connecting a wire to the antenna >> several >> feet long just in the shack does not show the noise hill, so it >> doesn't look >> like its something in the shack. >> >> >> >> The effect happens with a number of antennas and is not consistent at >> all. I >> live in a rural area with other houses hundreds of yards away. >> >> >> >> Has anyone else observed this sort of thing or have any idea what it >> might >> be? >> >> >> >> Thanks in advance! >> >> >> >> 73 - Mike WA8BXN >> >> _______________________________________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >> Knowledge Base: http://kc.flexradio.com/ Homepage: >> http://www.flexradio.com/ >> > > > _______________________________________________ > FlexRadio Systems Mailing List > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kc.flexradio.com/ Homepage: > http://www.flexradio.com/ > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ No virus found in this incoming message. 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