It might be a switching PSU on standby mode. I know one TV set that cycles in a similar way (producing some 'reverse TVI"), even when the numbers are not the same, it starts, charges the main capacitor, goes into standby and restarts when its voltage diminishes under a certain threshold.
73, Jose, CO2JA Dave 'Doc' Corio wrote: > Thanks for the info, Bruce. I didn't have a chance to record it or > measure it accurately before it disappeared Friday evening some time. As > to if it's time synced, I would have to guess that it is. It was > extremely close to 10 seconds on and 5 seconds off, and the number of > pulses was 55 during the "on" period. Granted, timing it with a > stopwatch is not exactly precise, but it was close enough that I'm > reasonably certain it's timed somehow. > > The simple fact that it stopped Friday night leads me to believe > it's some type of commercial activity. I've had the rig on a lot this > weekend, and haven't heard it once. It also stopped before I could log > exactly where it was. If I'm lucky, it's gone, never to return. I doubt > it, however. If it comes back, I'll get a recording of it and post it. > If you have a recording of yours, please send it to me! May not help, > but it sure couldn't hurt! > > Tnx es 73 > Dave > KB3MOW > > > Bruce Sawtelle wrote: >> Hi Dave, >> >> I have a similar type noise in our neighborhood. By doing some DF'ing, >> we've pinned it down to a neighbor's house, but haven't been >> successful yet in gaining their confidence to let us explore beyond >> their front door. Can here it on VHF when we're at their front porch. >> >> Is it "time synced", i.e. is the accuracy such that it's being derived >> from a 60Hz/Xtal time base. In my case, it's not. It comes on for >> APPROX 12 seconds and goes off for APPROX 3 seconds, but if I listen >> to it over a few minutes, it will drift up or down. Also, I noticed I >> can hear it at ~ 16.7KHz "offsets", which makes me think it could be >> PC video related. Not sure if it could be switching power supply >> related, I thought most of them were 100's Khz. Actually, It had been >> across the full 20M band last year when we were DF'ing, but now it's >> "discrete". I have a wav file I can send you if that would help. >> >> Fortunately, it's been down to S2-3 as of late. It also seems to be >> tied to colder weather (thermostat control??). BTW, the neighbor is >> 300-400 feet away in a suburban area (70' x 120' lots) . W5AHC is >> another ham in the neighborhood and he's ~100 fett closer and hears it >> as well. >> >> Hope this helps. Let me know what it ends up being. >> >> tnx es 73 >> Bruce - W3NJ
