Yesterday I tracked down RFI that has been bothering me on 160 meters for the past year. The source was a little hard to find because it's not always on. I finally had to use my SDR dongle with Ham i
Hi Don, Once you find out what the source is, please shoot me a screenshot of it for the RFI snapshot library. 73s and thanks, Dave NK7Z http://www.nk7z.net On 01/22/2018 06:15 AM, Don Kirk wrote: Ye
Quick follow up on my locating the source of the repeating 15 KHz signal (actually 15.6 KHz). Today I met with the suspect facilities machine controls engineer that just happens to be an inactive but
Hi Don, Funny similar call de WB9SBD. Can you hear the noise in the AM broadcast band? I have tracked many 160 meter noise sources on that band and by using a very simple portable AM radio tuned to a
I would try a a much smaller mag loop, like a foot in diameter. I have used a 6 inch loop in some cases, they are still sort of directional. Add a ferrite on the coax at the feed point. I have one lo
Hi Dave and gang, I totally agree on the smaller loop, but I believe what is also important is to factor in the implications of being in the near field. That's why I think going to a much higher freq
Hi, gents. Cortland here, KA5S. I had about a 30 year career in EMC engineering, and often had to locate specific sources of EMI. A quite small loop will do very well if one is in close proximity to
Having traveled similar tracks as Cortland (EMC/RFI Engineer), I can not stress the usefulness of the 3" loop. Just make one and use it. Take our word (writing) for its utility! Dave - WØLEV EMC Desi
Hi Cortland, Thanks for the info. I just constructed a 3" diameter loop (not tuned) using some pretty rigid RG58U, and will try it along with a 6" diameter tuned loop (adjustable between 20 and 30 MH
Great Don. Thanks for the info. I just constructed a 3" diameter loop (not tuned) using some pretty rigid RG58U, and will try it along with a 6" diameter tuned loop (adjustable between 20 and 30 MHz)
That's great, Don. The big advantage with getting up close with a magnetic loop is that the H field increases quite rapidly as you approach the conductor, so you won't need as much sensitivity and yo
Yes, indeed! Most electronic sources (and this is almost certainly and electronic source) are current sources -- they radiate by simple antenna action, AND also couple via their magnetic field. In th
I've tried loops in a variety of configurations, shielded, unshielded, balanced and unbalanced, but when I could get close to the H field source, shielding and balance really weren't a problem. I've
Please let us know what the outcome is. richard _______________________________________________ RFI mailing list RFI@contesting.com http://lists.contesting.com/mailman/listinfo/rfi
Look for AC/AC or AC/DC switching converters. I won't relate the story, but we had an incident where 208/3-phase was fed to several speed controllers on a large irrigation system (20-housepower AC mo
Brief update,. Many thanks to all the suggestions from everyone, and a special thanks to Courtland and David Eckhardt for really pushing the usefulness of the small untuned loop when in the near fiel
Great work, Don. It suggests that there are multiple sources, one much stronger than the other, or multiple points at which radiation takes place (or the magnetic field is developed). Be prepared fo
That system would be a Class A Part-15 device, so would have to meet the higher industrial limits. Locally, ie near the motors, controller or wiring, I could well imagine a 50+ dB increase in noise f
The system I related to was at a distance of about 200-feet and detectable out to a mile+. It was definitely not in compliance for either FCC or CE, as claimed on the labels. Dave - WØLEV -- *Dave -
And even if each WERE FCC Class A compliant, together, they could -- switching synchronously -- far exceed the limit. A cheap switcher might lock to noise on a common power source, whether generated