Dealing with RFI….

Discussion in 'Indoor Growing' started by jronnn, Mar 19, 2016.


    jronnn Well-Known Member

    hey guys I’m wondering how you deal with RFI? I know gavitas, LEDs and magnetic ballasts barely produce RFI and shortening the chord and faraday cages help but are there any other real fixes for electric ballasts?

    i know theres ferrite beads/chokes and RFI paint and products like nanolux filter kits but has any body ever tried these to know if they work? can’t find reviews anywhere. theres a few threads on this info but they’re quite outdated, theres got to be a good,simple solution by now. any e-ballasts/hoods/bulbs that don’t produce RFI at all? any input is appreciated!!!
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    ttystikk Well-Known Member

    Yes there are great lighting systems that don't generate RFI, one of these is 315W CMH lights. The special low frequency digital square wave ballast does not operate at high enough frequencies to be a problem.

    Another similar option would be a Horti Platinum ballast, this would run either an HPS or MH or 860W CDM Allstart and again be both highly efficient as HID goes and avoid high frequency issues.

    Yet another new option is @Revolution Micro and their new integrated DE fixture with low frequency digital square wave technology.

    Finally, COB LED runs on DC power which emits no RFI at all and is potentially the most efficient choice of the bunch- and certainly the most expensive.
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    Gquebed Well-Known Member

    Search "Revolution Ballast EMI Filter"
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    jronnn Well-Known Member

    thanks for the response!! but yeah my mind is 100% set on a digital ballast for hps bulbs and yeah i saw online hortilux says their ballasts run at a max of 4% THD but the only thing is they're so damn expensive!!! the phantom ballast runs at 32mhz so idk if that considered good or not for electric ballasts because it seems llke a lot of ballasts don't state their hertz. is the hortilux the only ballast you know of with no RFI? someone else said lumatek guarantees zero RFI but I've never seen this on any of the searches I've done. also, if i did get the phantom ballast, do you know how effective using refi paint or ferrite beads is?

    jronnn Well-Known Member

    i looked it up, the hydro store i go to actually has those in stock but have you ever used one yourself to know if it actually works or how effective/efficient it is? even on amazon the products have zero reviews

    Gquebed Well-Known Member

    No. I was going to. Then the cable company said it wasnt my place that was causing the "noise" so i just left it. But that product was recommended to me by @vostok so i would trust it...
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    vostok Well-Known Member

    Here the link:

    understand I've not used this one before RFI is such a diss these days it should be banned

    RFI that I have had I've suppressed with kitchen foil or as above shortened the cables

    RFI in a ballast, the old type should be sent to a tv technician or the equivalent

    and get fixed properly(imo)

    or better trash it for the new digital ballast or if like me with cash replace with Gravitas,

    but the utility bill bruises me each month

    good luck
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    ttystikk Well-Known Member

    Get the low frequency square wave ballast. You may not think it's a big deal, but that alone is worth 30% more actual light emitted per watt expended.

    You asked for advice, now do yourself a favor; don't whine about the advice you got, shut up and take it. You just got the best advice in the lighting business, bar none. Clear enough?

    grouch Well-Known Member

    I can pick up my meanwells with an am radio
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    ttystikk Well-Known Member

    Oh really? From how far away?

    grouch Well-Known Member

    Haven't checked
    Revolution Micro

    Revolution Micro Well-Known Member

    Hi, Greg Richter here. I designed the Revolution Deva light, and as an electronic engineer of 30+ years experience I can help you with your EMI/RFI question. Few things:

    CMH ballasts do not put out zero EMI. The boost PFC stage can radiate quite a lot, and all arc-light ballasts have this stage. Interestingly enough, LEDs are often the worst offenders for the same reasons. While LEDs are DC devices, they are run on switching AC power supplies which can make a lot of noise. A good example of an LED driver chip can be seen here:

    LED designs are based around switching power supplies and these generate EMI. Quite a lot of effort is expended in minimizing that EMI, and the Power Integrations link above talks about some of what they do in that particular chip to keep things quiet. So, LED does not equal low EMI. Often it means the opposite, as the absolute noisiest lights we ever tested were all LEDs. COB means that the LED chips are supplied on a board, which makes it easy for low-tech manufacturing, but doesn't change EMI spectra. The DRIVER is what generates the noise, and COB, discrete colors or white light LED are all driven from a switch-mode supply plugged into the AC mains. A lot of info out there is just plain wrong on this topic, and I'll do my best to set the records straight with facts, links, and stuff you can actually look up. :-)

    With any arc light be it HPS, Halide, CMH or other, the first stage is always a boost PFC (power factor correction) circuit whose job it is to draw power from the AC line in pulses and keep EMI low and power factor high. This stage is typically very noisy, and better designs use two or even three stage filters to keep the noise down.

    The output stage of an HID (arc light) ballast usually runs from 35 kHz to 100 kHz, and this can be a source of EMI as well. Name brands like Gavita, PL, Phantom and Galaxy do a lot of filtering to keep this noise down, and they are all much better now than they were two years ago. These particular ballasts did very well in our testing, which is why I mention them. Two years ago there were quite a few ballasts being sold that didn't even pass the minimum FCC limits for "commercial" as opposed to the tighter specs for "consumer" use, and there are quite a few still being sold that don't pass, as in are illegal to sell or operate. Google ARRL GROW LIGHT to read all about THAT big drama...

    The Phantom does not run at 32 MHz, it runs at 100 kHz like the Gavita and other similar designs, just FYI to keep the record straight!


    Our Revolution Deva light has a three stage EMI filter, and an output stage that runs 150 Hz. Not kilohertz, 150 cycles per second, which is fast enough for no flicker, but low enough the output stage puts out very, very little noise. I can post a video if you want showing the spectrum analyzer traces with the light at 1150W output generating about as much EMI as a Macbook laptop. It's very, very close to the limit of the analyzer to record it, and low enough to be considered "very good" for professional audio equipment, much less a grow light! We're really very proud of it. It's also digitally controlled, amazingly priced, and ... OK, I'm biased. Take a look.


    The EMI/RFI thing became a problem a while back and I talked with fellow ham Tom Thompson about his experiences in Colorado and then went on to develop an EMI filter for the lamp side of all the noisy ballasts. We sell the thing for close to cost, just to get the problem fixed. Hydrofarm has them in stock, and they work really well, and are mentioned above also. To fix the power line side, if your PFC stage is noisy, usually requires a redesign. If that's not happening, you can throw ferrite at it to dissipate the high frequency noise, likely to solve most problems. You can see the filter and a suggested fix for power line noise at where I specify a ferrite you can get from Mouser for a couple bucks:

    That paper also shows a well-know ballast spectacularly failing a conducted EMI test. You can pick up this POS at almost a half a mile with an AM radio!

    It's why we didn't make a power line filter -- you can just go buy a ferrite core or two and that should help quite a lot. Either you can buy a big ferrite and loop the cord a few times, or a few of them and clip them on. Adding Y capacitors and stuff is dangerous, and can put hazardous voltage on the case of the ballast so we didn't go that way. I can get into that a little if there's an interest, but this is already a freakin' Book of a post ...

    Faraday cages, BTW, are really hard to build in practice. The ones we use in the lab has lots of contact surfaces on the doors, screening, welded seams, etc. Better to stop the noise at the source than try and trap it all inside somehow.

    I'll stop there. If I can answer anything else, just let me know. Engineers are like musicians, we'll work an eight hour shift for money, then go hang out with our friends and do it all again for fun.

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    jronnn Well-Known Member

    hey i just want to say thank you very much for explaining all of that to me i really do appreciate it man!! but i have a few more questions...

    1. so basically the higher the hertz on the ballast, the more RFI/EMI and harmonic distortion it puts out?

    2. so you're saying phantom ballasts are lying when they say they have "Smart Alert Technology utilizes a 32MHz fully integrated microprocessor"?

    3. are ferrite beads effective enough that it really doesn't matter what ballast i get because i can just slap a bunch of ferrites on if need be?

    4. also, just to be clear, you're saying you don't need a filter for the wire going from the power to the ballast? just throw ferrite beads on the wire?

    5. its funny you sent me the link to the EMI filter because i was going to buy those for each one of my ballasts either way lol, so i assume the EMI filters are quite effective? it just sucks because theres zero reviews on the product and it seems like no one has tried it so i wasn't sure if they're effective or worth the $30. i saw a nanolux filter on mostergardens and it said it was discontinued so i was thinking maybe none bought them because they don't work

    6. i think your lights are really well priced and really neat, do you know of any journals you can link me too of people using them? and how do they stay cool? i didn't see anything about a fan or anything on the website, what are they designed more for growers with a lot of ceiling clearance like gavita?
    Last edited: Mar 21, 2016
    Revolution Micro

    Revolution Micro Well-Known Member

    Anytime! Taking you questions one at a time:

    1. The output frequency in Hertz, or kilohertz, on a ballast impacts the cost of the design more than anything else. Higher frequency means smaller inductors, and the resonant inductor (used to strike the bulb in these designs) is the single most expensive item on the board. Higher frequency means cheaper to make, which is why high-performance DC-DC converter chips are screaming along at 4 MHz, 40 times higher than 100 kHz ballasts. Higher frequency at the output means more work for the design engineer to keep the EMI low, true enough, but that doesn't mean "high frequency = bad". Low freq square wave is like comparing an gas car to a Diesel car -- they can both run very clean and efficiently, but the engineers have to work a lot harder with the Diesel. A low frequency output at a hundred Hertz is 1000 times further away from the AM radio band and telephone DS1 and DOCSIS basebands than a 100 kHz ballast. Some are really quite good, but a low frequency design doesn't have this problem to solve in the first place which is why a lot of the majors (Hortilux, GE, me, Philips) went that way, and technology is generally going that direction. Long term, most HID ballasts will probably be square wave.

    On THD:

    Harmonic distortion is meaningless in this context. If we're building audio amps, yes, it matters, but we're not. Heating plasma can be done with a square wave, sine wave, or DC. Harmonic distortion measures how close to a pure sine wave the signal is. But it doesn't matter! DC is perfection, and is 100% THD. A square wave works beautifully (which is why GE, Hortilux, Revolution, etc. use them!) but it is 40%+ THD. The lamp doesn't care or notice how close to a sine wave the current is. So bah and pooh on THAT. It's just something for marketing people to talk about "Ooh twin turbo, low THD". It's crap. On the INPUT side, it does matter. The PFC stage is drawing power from the mains and they ARE sine waves. So low THD there is important to not distort the power line for everyone else like your other ballasts, stereo, TV, etc.

    For a quick read on THD in PFC stages, Lambda has a good article here: Export/...pfc_switchmode_powersupplies.pdf?redirected=1

    Power Factor Correction (PFC) stages are pretty much required to meet European standards, and these standards include THD computed to the 39th harmonic. THD in the output stage is pure marketing spew. The lamp doesn't notice or care what the waveform is.

    2. The Phantom guys are not lying, I think you mixed up two separate things: The frequency of the ballast output is how fast the light switches from positive to negative, and that frequency can radiate on longer lamp cords. The output is 100 kHz. The processor speed, the 32 MHz clock speed of the CPU, is how fast the internal microcontroller is running and has nothing to do with output frequency. That's like the clock speed on a computer, just s-l-o-w compared to a laptop since it's just an MCU, and not a full-blown fire-breathing Intel chipset. My Deva MCU runs at 20 MHz, clock speed, so anything in that range is pretty common. Below 10 MHz is getting too slow to be precise, anything above 16 MHz is enough, 20 MHz is overkill, 32 MHz is a shit-ton of fast. Hope that helps! BTW, I build a lot of gear for Hydrofarm, and if they are going to print something that isn't technically right I say something about it, and they've always fixed it when I do. I think they want to get it right, or maybe I'm just that big a pain in the ass, but either way they're pretty good about specs. :-)

    3. Give me enough Ferrites, and I shall move the earth.... Uh, not really. :-) Ferrite is a last-ditch, desperate, ball thrown from mid court while the buzzer sounds. The right way to suppress conducted EMI is with a two or three stage fillter, which costs money. That's why some cheap-asses don't do it, and very few did it well a few years back. Here's what these input stages look like:

    The problem is Leakage Current. See the capacitors marked Cy1 and Cy2? These provide a path to earth for high frequency common-mode noise. That's good. They're also made by mortals and leak current at 60 Hz from the powerline. That puts a tickle of leakage current on the case of your ballast. A little is fine, is safe, and passes UL. Adding another filter stage adds more Cy caps, and is NOT safe. Leakage currents can be dangerous (as in ZAP YER DEAD dangerous) which is why we take the Last Chance For Gas approach with ferrites. Adding another common mode core like Lcm in the pic doesn't help without Cy's to tune it, so if your filter stage is Sheisse, it's redesign the filter, throw ferrites at it, or buy a ballast designed by adults and hasn't been value-engineered to death.

    So: Better to start with a good product than try to fix it later with likely mixed results. If they cheaped out on the EMI filter stage, you KNOW they cheaped out on the filter capacitors and output transistors, and the ballast isn't going to live long or maintain brightness over the years.

    4. Ferrite is safe, filters with additional Cy capacitors may not be. Ferrites will help, but may not be enough depending on how bad it was to start with. The ballast curve in my previous post won't be legal (forget good, just shooting for LEGAL) without redesigning the front end. No amount of ferrite will get you there. Best answer is start with a good ballast. There are good ones out there, and some very good ones too.

    5. Yeah, those are my design. I built a bunch of them to fix some noisy ballasts causing problems. They work well, and I put them out for about cost. I think that's why Nanolux dropped theirs, since mine was just so cheap, and also technically very good.

    6. Our lights are an all-new design and we've got them going to people for test and review. We've got a few guys on this board going to test them too. :-) Fans suck. My background is avionics, and you don't want to ground a plane because a cheap-ass fan took a dive. The heatsink design on the Deva is pretty slick -- you can put your hand anywhere on it while it's running. The fins are just MONSTERS, and she runs warm but not hot. Ceiling clearance is, maybe, 10 inches for air movement? If you have fans moving air in the room so it won't get blazing hot near the ceiling you can go less. Glad you like -- they're very, very different than any ballast you've seen. No resonant ignition, low frequency output, very, very low EMI, and intelligent adaptive control means constant brightness at any setting. Most ballasts are +/- 15% in brightness from ballast to ballast. We designed for 1% and guarantee 1.5%. What you set is what you get. There's more, but you asked about EMI not my new light...

    Hope that helps!


    Abucks Well-Known Member

    Solistek matrix. Purchased two of them a while back, and I'm sticking with them. From everything I've read, they put out less rfi then any other ballast.

    Abucks Well-Known Member

    Great read!
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    Abucks Well-Known Member

    Have you had any experience with solistek? I started buying these because of their, and others claim of low efi. They are costly, but worth it if they work as claimed. Thanks for the all the info!
    Revolution Micro

    Revolution Micro Well-Known Member

    I've personally tested the Revolutiuon (mine, of course), Gavita, Phantom, Galaxy and PL. We tested quite a few, and I don't like to bash people, so I'd prefer to say that these did well rather than list the Bad and the Ugly. I haven't tested any Solistek gear recently, only a couple years back in the Phoenix lab, so I'm not sure, but I do know people that speak highly of it.
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    Abucks Well-Known Member

    Thank you for the reply. You've already cleared up a lot of questions I had on this subject. We need more people like you on these sites.

    jronnn Well-Known Member

    thanks man that was indeed a great read, i appreciate all your help.

    From what I've gathered from slight hints is hortilux (mentioned the most lol) is the best one to go with, someone actually just said to me on another post "Buy ferrite chokes for power supply and out put. 2 for each cord.. Or buy the latest Galaxy ballast and other Sunlight compatible equip which has ferrite/rfi sheathing built in." which i had no idea about, nor do i know how factual that statement is but i was looking at the phantom II because they're quite a bit cheaper than hortilux and seem to be of real good quality but if you think hortilux is my best shot at getting the lowest EMI (if all the circumstances are the same) then i think I'm going to just go searching for the best priced hortilux ballasts because i couldn't sleep at night knowing my house is basically a big ass antenna lol but i thought your lights were already up for sale and everything, its too bad too because they look really nice and the price is really good especially since it comes with a bulb... but if anything ill be buying 16 of your emi filters lol. i was also looking at hortilux youtube channel where they compare their platinum series and gold series ballasts and they say their square wave ballasts are the platinum ones and their gold series uses a "sine wave design" so were you talking about their platinum series? cause they charge out the ass for the platinum ones lol
    Last edited: Mar 21, 2016

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