Electronic ballasts and RF/cable interference, AGAIN

[clowntown]

What do you folks think about Poly Shield? Good for just IR, or RF as well?

Background: One reason I ask is during my days as an IT guy, I oftentimes worked in these "Internet Data Centers", buildings that housed lots of high-end, mission-critical web servers and the like. All of the major websites are housed in IDC's like these, with raised floors, tons of A/C, etc. Anyways, each customer is assigned a particular amount of floor space, typically divided by a chainlink fence cage. However, the really high-end customers with sensitive data flowing would opt for what was marketed as "data vaults", which were enclosures that were lined with a copper mesh screen material. They said this copper mesh would block RF signals or such, so that no data can accidentally escape through the cables, and no data across the cables can otherwise be interfered from outside sources. This was a requirement for a certain level of security clearance of computing, for computers holding / processing sensitive data.

 

[Stoney Bologna]

Poly Shield is the most effecient RF blocker that I'm aware of. I work in the RFID industry and whenever we need to shield something from UHF radio emmision we use a layer of mylar sandwiched to a layer of black poly, which is a cheapo DIY version of the Poly Shield. The mylar completely reflects the signal and the poly absorbs it to keep it from scattering all over the place. If I was gonna make a good RF shielding device I'd use Poly Shield or a simliar product.

 

[Stoney Bologna]

Hey Stonewall,

The AM radio is another thing like the cell phone that would be hard to block the signal entirely. It's a pretty high amplitude signal, but I believe it will be slightly easier to block than the cell phone cause cell phone companies use all sorts of crazy patented technology to get there signal to penetrate damn near everything.

I didn't know that most problems with ballast EMI were with AM radio interference. That's good to know.

 

[clowntown]

I didn't know that most problems with ballast EMI were with AM radio interference. That's good to know.

No, I'm hearing about problems with all sorts of stuff. Of interest are digital cable / Internet, DSL, and other high-frequency bands that people will really notice. If it were just AM radio, I couldn't give a rat's ass... who really listens to AM nowadays, and if they did they would just think that it's a poor signal.

 

[stonewall]

With the mylar/black poly, which side is in? the black right?


I figured digital cable and such was a high enough frequency to not be affected? I also thought fiber optics weren't affected. Doesn't the frequency of the rfI have to be near the frequency of the signal interfered with?


Most e-ballasts are in the 20-40 kilohertz range, some over 100 Khetz.


See now I am showing how much I truly don't know on the subject.

 

[Guest]

digital cable is kHz 555000, and now i'm kinda glad I did not buy one 1 year ago when I got a new ballast because it would be fucking with my wireless network, transmission from my whether station, and maybe even my tv.

 

[een]

When manufactures claim something is RF shielded, it means that most of the electrical components are cover with a high carbon content polymer (aka black plastic!).

It means they covered it with whatever they had to to block RF that was above the allwed limits. If they use a plastic housing it's because they designed it carefully so as not to need an expensive, heavy metal housing.

There's an easy solution if you are having RF interference problems. Surround the area/room/cabinet that contains the ballast with a layer or two of black poly.

Remember, black plastic absorbs RF like a sponge, where as metal reflects it like a mirror. Wet wood absorbs RF like a champ too but that's not as easy to work with as black poly.

I'm pretty sure that is wrong, but you seem confident about it so I am going to check with other sources just incase you are a super-smart physicist with a tricky argument. Everything I have ever read or done in the real world (I ahve an ee degree but I am 28 so not a know-it-all either) has indicated that plastic of any colour is not used for RF shielding.

For example, just about all whip antenna's on cars are covered in black plastic.

I worked on a GPS project, which is a very weak signal, and the state-of-the-art antenna was covered in black plastic.

I worked in a telecommunications company under an experienced PhD engineer (who knows how to get the best most cost effective design), and the box we chose for our electronics cost over $800 due to all the metal shielding pieces. THe electronics weren't designed to to radiate RF, that was just to block the incidental stuff.

As Stonewall said you can get plastic that has been impregnated (with carbon?, I don't know) to help shielding but it is more expensive than normal plastic, it's not nearly as effective as metal, and probably isn't easily available in a form that anyone here can use (a sheath to go over a cable) so it's a specious argument.

 

[een]

You'll need a spectrum analyzer; UHF antena; function generator; and a little more insight on the nature of photons to be able to measure a material's resistance to an electromagnetic wave.

You should really trust me on this one because as it turns out the electrons in the carbon atom get really excited when they get hit with photons that are about 100 nanometers to several feet in length. This causes them to jump to a higher energy state and absorb some of the energy from the wave in doing so. An RF signal is just a stream of photons that are a couple centimeters to serveral feet in length. Hence, plastics containg carbon atoms attenuate RF signals. Isn't that great!

Why are you talking about photons? The goverment isn't going to come to your door because you are making too much light. We're talking about RF, you're not trying to say "light is RF therefore black poly blocks RF" are you?. I am interested to know how you do the experiment with that equipment, with the photons and the spectrum analyzer and the UHF antenna?

 

[i3inary]

i just wanted to add that i do have a cable modem...and yes it did go down while my ballasts were in use...although i had no idea at the time what the issue was...

the fact that i had 4 600w ballasts less than 15 ft from my cable demarc may have also contributed to the signal to noise ratio being strong enough to take down all everyone on the same cable tap...

all i can tell you is if you are worried at all about security my suggestion is to stick with magnetic ballasts for now...no electricity or bulb savings will be enough to warrant the extra risks for me..

i was also not impressed at all by the 135 degree external temps....i literally could not pick them up without burning myself...also more of a firehazzard imo.

 

[Guest]

my coil ballast is silent and only gets around 110*F on the outside

 

[clowntown]

i3inary, thanks for stopping by and sharing that info!

My "new model" 600w/120v Lumatek arrived yesterday, so today after I pick up a surge protector I will test things out and share the results. It won't be 100% conclusive by all means, but may show whether Lumatek fixed these issues in their new units.

As for the heat thing... I've heard the opposite. Most say that their electronic ballasts run much cooler than their coil counterparts, but again this is something I can tell you more about tomorrow at least for the Lumatek 600/120.

After some more testing with more equipment, I may attempt to compile a list/chart of electronic ballasts and their "RF safety status".

Thanks everyone for the input,

 

[stonewall]

According to the quantum theory, all energy is transmitted and absorbed in discrete particles called quanta or photons.

I am hoping Stoney Bologna comes back and answers some of our questions, I was just starting to like the guy.

 

[i3inary]

As for the heat thing... I've heard the opposite. Most say that their electronic ballasts run much cooler than their coil counterparts, but again this is something I can tell you more about tomorrow at least for the Lumatek 600/120.

i should add that my digital ballasts did not have fans...i am sure with a fan those temps would be much lower..but then you add another piece of the room that is mechanical and prone to failure...fans in my experience are not to be trusted heheh...at least computer fans.

 

[fuzygrowth]

if rf is leaking through the lamp cord wouldn't regular foil tape wrapped around the length of the cord kill it? they also make a copper tape which should be in the siding dept.

 

[een]

According to the quantum theory, all energy is transmitted and absorbed in discrete particles called quanta or photons.

I am hoping Stoney Bologna comes back and answers some of our questions, I was just starting to like the guy.

Go to wikipedia and read wave-partical theory, sometimes it acts like a particle sometimes like a wave. At the frequencies we're worried about it's a wave and 'black poly' doesn't do anything.

 

[The Slickster]

The main reason for opting for a digi, is not solely for extra light, or less electricity consumption, etc. But for its different frequency than what the standard coil ballast emits which too many law enforcement or any other people "looking" for frequencies normally generated by a magnetic coil ballasts are very familiar with by now. So since the digital is a different frequency that would be the upside. Also, just as the heat sinks on a car amplifier will get too hot to touch, that only means it is doing a good job of diffusing and releasing the heat. If a ballast does not get hot, it is likely keeping the heat inside and decreasing lifespan, effectiveness, lumen output, and using more electricity amongst other things. It could be possible, for ballasts other than the Lumateks, to use the poly-shield mirror facing in, to enclose the ballast, having the black facing out, and the reflective mylar side facing in.

 

[homerq]

I know of a 400w HIDHUT switchable 120v digital ballast.
I can tell you that it is only shielded by 1 piece of sheetrock, and is about 1-2' away from:

1 computer with wireless internet connection that is 25 feet away
1 plasma tv
1 HDTV satellite tv box
1 Home Theatre sound system
1 Bose Subwoofer

I can say for certain that there is NO INTERFERENCE with ANY of these items.
Seems to work great. Hope this helps.

 

[clowntown]

If you don't mind, could you please do some more testing (AM/FM radio, cell phone, cordless phone, anything else) and post your results on the thread in my signature?

If you'd like, you can just PM me and I'll add it to the list.

Thanks.