I need help to identify, and hopefully eliminate, an unknown source of RFI. I'm sure some of you have dealt with this before, so I hope to take advantage of any knowledge you may be able to provide. Please help if you can. First, let me describe the problem: On 40m I get a recurring 'whispy' noise with narrow spacing in the band at about 20KHz apart. The sound could be likened to someone holding a microphone out of the window of a moving car, or a whip antenna in a high wind. On the SDR they appear like a signal, but have a whispy appearance as the frequency shifts slightly every second or so. I've attached a picture. In it you'll notice the little whispy "signals" at a 20Khz spacing. What I've done so far: My system is set up well from a grounding perspective. Furthermore, I have "clean" power and ground going to all of my rigs, and also everything that is connected to them. By clean, I mean that the AC power supplied to everything runs through a series of loops of Romex running through 4 large toroids. Antenna is grounded at the feedpoint, and the coax is grounded at the shack. The RG-213 runs through a choke balun. The two rigs I have set up are run through separate power supplies. One of the power supplies is an Alinko DM-30T, and the other is a quasi-homebrew PS made from an old Dell server power supply (makes very clean power). Both rigs will pick up the errant signals no matter which PS they are connected to. They even pick it up on battery power. I've shut down the entire power grid in the house looking for a local source by flipping the main breaker, to no avail. The errant signals remain. In hopes to track it down, I connected a resonant loop antenna to my FT-891. With the FT-891 strapped around my neck, and on battery power, I have attempted to walk the yard to locate the source, but it appears that the loop antenna will not pick up the noise. With the exception of the 'noise' guy down the street, my station is relatively quiet. But I know what that guy's noise sounds like, and it's not him. These signals are making it difficult to operate, and I'm looking for some help to mitigate the issue. Any information you can offer will be greatly appreciated.