OK, SOMEONE had to correct the subject line. -- Scott K9MA k9ma@sdellington.us _______________________________________________ RFI mailing list RFI@contesting.com http://lists.contesting.com/mailman/
Just something to add to the database: I recently had a noise source appear on 160. As per my usual procedure, I re-transmitted the 160 noise to my cellphone and took a walk with the VHF tracker. (Th
I can't stress enough the value of listening to the noise received by your HF receiver at the home QTH while you are listening to tracking receivers.There is always a pattern to the noise; when you f
With any kind of direction finding antenna, you have to be aware of polarization. A vertically polarized loop, for example, may give very misleading bearings if the noise happens to be mostly horizon
Back in my spacecraft hardware building career, it was well known that Teflon would "cold flow". Great care was taken where wires went around corners, etc., that there was no pressure on the insulati
I have noticed a similar phenomenon when testing transmitters using antennas, rather than attenuators. All kinds of garbage gets generated, apparently by every device in the vicinity capable of nonli
It's vitally important to make sure you are listening to the source of the real problem. Otherwise, you can waste a lot of time tracking down extraneous noise sources. I've found the best way to do t
Ah, but there's that little Part 15 notice in the owner's manual, something about "May not cause interference..." Good luck with that. 73, Scott K9MA The solar systems must also meet conducted emissi
Ferrite common mode chokes are very unlikely to have adverse effects on the electronics, unlike bypass capacitors. (Slow rise times, oscillating op amps, etc.) And they often ARE effective at reducin
Most likely the compressor, just because it's larger. 73, Scott K9MA On 2/8/2020 12:26, Kim Elmore wrote: My understanding is that the RFI is generated by the variable speed motor controls. In these
SOME kinds of home electronics devices have gotten better. 25 years ago, my YL bought a fairly expensive electronic piano. Despite several pounds of ferrites on the power cord, I still wiped it out.
No, the phenomenon I'm talking about is caused by even low frequency RF getting into circuitry where it doesn't belong. It has nothing to do with the operating frequency of the susceptible device. On
Just about every modern appliance with motors uses a variable speed drive of this sort. Washers, refrigerators, furnaces, etc. It's basically a switching supply. It can be made RFI quiet, if it's de
I can only dream of such a response. Here (Madison Gas and Electric), it takes months. 73, Scott K9MA RFI Services Michael Martin 240-508-3760 rfiservices.com Get BlueMail for Android On Feb 18, 2020
Most of the power line noise sources I've tracked down involved poorly bonded metal-to-metal contact near, but not connected to, power lines. No doubt there is a tiny arc happening between these piec
One has to wonder, for all the trouble these things have caused, how many fires they've actually prevented. 73, Scott K9MA Would you know the and model of these breakers? Maybe some models are more s
Ordinary ground fault interrupters do that. Some of them are sensitive to RF, too. Arc fault interrupters, in addition, are supposed to detect arcing, which can start a fire. That's a good thing. Unf
It does seem that newer models of most everything electronic have better RFI characteristics, in both directions. Im sure there are exceptions, like those $3 USB chargers. 73, Scott K9MA -- Scott Ell
Looks like a switching power supply running at 55 kHz. If you zoom in on one of the spikes, you'll probably see an asymmetrical spectrum, with a longer tail on one side. And it will probably be drift
Ah, but they ARE drifting! I don't think the resolution in this image is good enough to see the modulation. The switching supplies I see usually are spread out over just a couple kHz. 73, Scott K9MA