Yes, thanks. Sorry to hear you had such a nasty problem there. I’m just trying to understand why the RFI situation in your case was so bad and why it required using so many reverse phase (back of AC cycle cutoff) dimmers. It sounds like the bulbs were proper dimming type, and if from the major manufacturers are probably be ok to use, though every dimmer manufacturer has a compatibility chart. From your description there were also electronic low voltage types under counters and similar locations, and these may or may not be well behaved (and require reverse phase dimming) but I’m sure you would have noted if the problems were only from those lights. Most common modern dimmers are of the forward phase type like the old incandescent only types, but the LED compatible versions have additional features for use with LED lamps. But the basic circuit is triac and they all should incorporate a modest inductive RFI filter (at least if made by a major manufacturer and not some junk from Asia). However, they have a limit to the wattage of LEDs because worst case electronic ballast in LED bulbs can have a very high inrush current, exceeding the dimmer current rating, and producing a lot of RFI. For a typical 600 watt incandescent rating the LED rating is usually 150 watts or so which would be 10 bulbs assuming, say, 15 watts each. So perhaps part of the problem was the number of bulbs on each dimmer? From reading the available literature on the Lutron website, the Maestro Pro that solved your problems allows either forward phase (front of AC cycle cut off) or reverse phase, selectable at installation. Reverse phase eliminates the inrush current problem, and RFI from the cut off is more easily handled with a snubbing capacitor, but they are more expensive because FET circuitry and control chip is required, and they are produced in lower volumes. I didn’t see any other difference disclosed from the usual forward phase dimmers. Do you know if reverse phase was selected on the Pro? Do you recall what dimmer brand and models were originally installed?
Again, thanks, Bob. You prove that hams know a lot -- and some know much more than Tom and me. Interestingly, in every case of RF noise at various neighbors' homes, new LEDs of one type or another were installed and either the dimmers were not replaced or, more commonly, very inexpensive Lutron slide dimmers were installed. At my own home, I installed new recessed ceiling LEDs in three rooms and upgraded the dimmers to the best Lutron dimmers I could find at Lowe's (about $20 each). The noise was bad. Once I installed the Lutron MA-Pro, the noise disappeared. You might be right about the number of bulbs on some of the dimmer circuits. In my neighborhood, however, the replacement LEDs are mostly recessed lights in either kitchens or lower-level family rooms. So normally it would be about 6-8 bulbs. With my immediate neighbor's dining room chandelier, I first tried unscrewing bulbs, and even with one small bulb left in the lamp it was making the same level of noise. I did not try anything like this with the recessed lights at neighbors -- or at my own home. Bob, what's your sense of how the noise travels to all homes on the side "output" side of the power company transformer? Also, what would you have done in my situation? How would you have tried to search and solve the problem? Thanks so much. Quin
As I read the installation sheet, the reverse phase is default IF the neutral was connected (it can also be programmed). I presume you connected a neutral when it was installed, so it would have been in reverse phase (or you programmed it for reverse)...? That might be why I haven't experienced much RFI here because we have only a few bulbs at most per dimmer. Usually some number of homes are fed from the secondary of one distribution transformer, depending on the distances between them. The dimmed current waveform is very distorted from a smooth sinusoid and has sharp edges where the AC cycle has been cut off. LEDs can make this much worse because (depending on quality) the electronic ballast or low voltage power supply will draw a large spike of current at the turn on for a forward phase dimmer. This current has a lot of harmonics and HF RF components. The transformer is has a non-zero impedance, so the voltage on the secondary also has this noise, and some amount of it is then conducted to all the other houses connected on the transformer secondary. (BTW this can also come from switching power supplies or industrial equipment that does not employ good "power factor correction" to avoid too much deviation from a sinusoidal current shape. This can even cause problems to the power utility because it increases harmonics, phase angle, and I^2*R losses). Also, the wiring in the house with the problem dimmer can act like antennas and couple to nearby conductors (such as the cable coax) or radiate directly to a nearby ham antenna. (I'm assuming there isn't some error in grounding or whatever in the power distribution or wiring in the houses) I think you did everything I would have. It sounds like there are a high number of dimmers and bulbs in the neighborhood (and low voltage systems) so there was a lot of noise being generated, and it makes sense that the reverse phase dimmer eliminated or reduced it substantially. Thanks for bringing this to our attention!
led lights, dimmers, and computer stations try living in a hotel for 25 years. this is a radio amateur nightmare. The rf hash is so wrong here that 1/2, mile, either way, is an s9 plus 24/7. I have to rely on a remote SDR site in order to hear decent and the nearest site is 40 miles away. So giving a signal report on 80/75 really isn't correct. Most signals are strong enough on 40-10 meters where I don't need the help of a remote SDR, But it is nice to compare signals with it anyways and it also serves as a transmission monitor to listen to my transmitted signal.
But sometimes those disturbances cant be found. In the picture is to see a former problem of mine. The frequency is of a local repeater with a heavy signal. And the spectroscope shows jabber which killed the modulation of the repeater. It was for about two years or so. There is to say that I had jabber only at the 2M band. And this from aircontrol to hamradio and official departments like the police. The signal wasnt stable and runs up to S9+. And I called a professional team from the Bundesnetzagentur to find the jamming signal for to clear the band around my home. And there is to say, that these teams are equiped with the finest measuring instruments and a radio detector van. In the end the team just found a suspicious streak and they couldnt clean it because the signal wasnt steady around the clock. But I have to say, that the signal is away now for a longer time. Maybe it was just some kind of silly flashing christmas light or a cheap LED which is now broken. Dont hope that it will come back again.
Great info on the RFI.... These Lutron dimmers are available and are not causing any RFI at this QTH: Lutron Caséta Smart Dimmer Switch for ELV+ Bulbs, 250W LED, PD-5NE-xx While higher cost, they work with a Lutron bridge allowing fully automated lighting - Very convenient... _..-- k3Tim
Thanks, Tim. How did you happen to use them? Quin, K8QS, Co-Host, Ham Radio Perspectives--see the videos https://www.youtube.com/c/hamradioperspectives/videos
I wanted to automate some accent indoor lights and tried one of these dimmers and also to test for RFI. With that success all light switches in the home were changed out to the Maestro type, including ceiling fans. Lighting turns on/off automatically, including ON before sunset. Very convenient and the switches lend a modern look. A simple BoG antenna also helps reduce RFI from neighbors will receiving on all HF bands. It's not grounded at both ends (as a BoG should be) but was simple to deploy and works well.
My great RF generator was a new refrigerator I bought. This is a Cafe refrigerator based on the GE Profile. Anyhow, this sucker creates 18db on no less than 3 bands.. 15, 17 and 20Meters. Initially I would just throw the breaker when I was on the radio, but that lasted only so long because at one point I forgot to turn the breaker back on. Also, the wife wasn't pleased when she would go in the fridge only to find out it was turned off. Anyhow, I bought a toroid refrigerator kit from dxengineering, that has a huge core to wrap the power cord with, and that did help. I'm thinking it took the noise level down at least 6db, so I was happier. However, I have a problem with just leaving well enough alone, like a lot of us hams do, and bought another toroid kit with different size toroids. I'm thinking the day the kit came in, I took off the back of the fridge (2 separate panels), and starting beading up all of the wires I could see running to different parts of the fridge. The fridge was buttoned back up, and found that around/approx 6 more db of noise was saved. This was much better, but surely I can get it lower, so I exposed the wires from the ice maker (In the door), and found the wiring leading to the back of the fridge and beaded it up, and managed to get the noise down to around 3db, depending on which components are running at the time. Here's the thing about refrigerator noise if you didn't catch it... Just because the power cord is beaded up, you might continue to get noise depending on when the ice maker kicks in or when the compressor fires up or perhaps the evaporator. So, you might have to do like I did and take the darn thing apart to find all the wiring and bead it up. Ah, the expense and trouble we go through to keep the rf nose down. Best Regards, P.S. Yes, the wife knows I'm nuts.
Thanks much, Dave. Your QRZ page is fun. I can see you battling the refrigerator with your 10-meter antenna. Q
Great information. I had a similar problem. I was getting S8 noise level so I started disconnecting things and found my Seagate 2TB freestanding backup drive was the culprit. Since I disconnected it the noise dropped to S2 or lower.
During my formative years folks would relate how vibrant the AM band is at night, but all I heard was buzz. Then one night it was clear and amazing, no buzz, for a while, then it came roaring back. I quickly realized that Dad had flipped on a light - at the other end of the house - that he powered with a homebrew dimmer switch in a wall box connected to outlets in another wall box that sat beneath an end table - just enough light to guide someone through the room. From then on it was a matter of dealing with Dad when I wanted to listen, and before long there was a new dimmable lamp there
In my years, when I used the 11M band, my parents had to deal with my emitted disturbances too. Because the VU levelmeter, filled with many small lamps in the VHS recorder, began to glow with every PTT of mine. In the end there is to say, that every party got problems with the interruptions, equal from which side.
