LED Trims & OTA Interference

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George Stolz

George Stolz

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Hospital Master Electrician
When I turn my dining room cans on the TVs in the house go digital. Pretty sure the trims are broadcasting the interference. What should I try first? It diminishes proportionately as the LEDs are unplugged working away from the antenna. Cans almost as close but a bit further have almost no deleterious effects.
 
Do you have cable or dish? I use the old rabbit ears and don't have any trouble.

I only have one led. I'm trying it out to see if it lasts twenty years. If it does I will buy another. Send me some more and I will see if my tv reception suffers.
 
iwire said:
Aren't you supposed to be holding your wife's hand right now? :)
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This kid is going to drag this out for hours. In the meantime there's likely a father-in-law pacing around my dining room with nothing to heap his anxieties upon aside from the poor reception on the TV we installed yesterday. Priorities, man!
 
ActionDave said:
Do you have cable or dish? I use the old rabbit ears and don't have any trouble.

I only have one led. I'm trying it out to see if it lasts twenty years. If it does I will buy another. Send me some more and I will see if my tv reception suffers.
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OTA - $50 70 mile Walmart antenna doing a fantastic job as long as I leave my cans off.
 
George Stolz said:
... Cans almost as close but a bit further have almost no deleterious effects.
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One of the interesting characteristics of digital TV is the ability to automatically correct a large number of small errors in the digital signal.
Typically there is no easy to see indication of just how hard the TV is computing to fix errors in the received signal, so the interference can increase progressively with no apparent ill effects until it crosses that threshold of possible error correction and starts to show problems in the picture.
As the interference gets progressively worse from there it can lead to seconds at a time of complete dropout of the signal (the image may freeze or it may just break up.)

It really sounds like your problem is radiated energy hitting the antenna, rather than conducted RF over the wires, so there is no much you can do to keep the RF out of the antenna wires. Possibly putting an RF filter right at the connection to each can will help, as may being sure that all the metal parts of the can and trim are bonded together (grounding alone probably will not help.) If part of the trim is plastic rather than metal, making an aluminum foil hat for it may actually help.
Try dropping the trim down while it is still operating and changing the orientation to see if it selectively radiates RF in one set of directions.

Based on other reported experiences, the best remedy possible will be to replace the LED/driver combination with a different brand, trying first a brand that has been reported here to be interference free. You can replace one can near the antenna first and test with it before going all the way to replace all of them.
 
First, check for proper grounding at each fixture location instead of assuming and ensure each fixture is properly grounded.

The next thing is try a different model. This has resolved problems for many people. If you get another brand but looks exactly identical as far as your eyes can tell, the OEM is probably the same.

On a related note, if you start experience interference with licensed spectrum, such as radio and TV reception starting after a recently installed LEDs in another household, property or municipal work, you have the right to ask them to correct it and request enforcement actions to the FCC if they do not resolve it.
 
Grab an AM radio (remember those?) :) and tune it in between stations. Or not...sometimes the hash from a bad light will wipe out all reception.

I haven't experimented much with LED lights yet, as my current batch of home CFL's keeps chugging along. I do have a few GE light sticks and haven't noticed any problems.

One of my clients has been fighting RFI from bad T8 ballasts for years. All will be well for months, then BUZZZZZZ. Bad when a radio station can't hear itself.

Hopefully it's not a problem common to the brand of lights you have. As Electric-Light suggested, I'd try a different brand of light in a fixture close to the antenna and see if that makes a difference.

Do you have any RF amps in your antenna system?
 
Electric-Light said:
...On a related note, if you start experience interference with licensed spectrum, such as radio and TV reception starting after a recently installed LEDs in another household, property or municipal work, you have the right to ask them to correct it and request enforcement actions to the FCC if they do not resolve it.
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I don't recall where I read it (might have been here!) a few years ago about a FL ballast spewing RFI that was interfering with aircraft frequencies out west. When the feds showed up and demanded he fix the light, the shop owner gave the wrong answer.:)
 
Electric-Light said:
...

On a related note, if you start experience interference with licensed spectrum, such as radio and TV reception starting after a recently installed LEDs in another household, property or municipal work, you have the right to ask them to correct it and request enforcement actions to the FCC if they do not resolve it.
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Before you go down that route, make sure that the LED units are FCC approved for residential (Class B) use instead of just commercial (Class A) RF emissions which are more lenient.
In fact, the first thing I would look at was whether your units are Class B or not.
 
GoldDigger said:
Before you go down that route, make sure that the LED units are FCC approved for residential (Class B) use instead of just commercial (Class A) RF emissions which are more lenient.
In fact, the first thing I would look at was whether your units are Class B or not.
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The answer pertains to interference producing devices in control of others affecting you. For example, your ability to enjoy certain AM stations after property management company made the decision to install LED lights and you have reasonable proof, such as the loss of reception comes and goes with the lights cycling and absence of interference before these lights being installed.
 
Electric-Light said:
The answer pertains to interference producing devices in control of others affecting you. For example, your ability to enjoy certain AM stations after property management company made the decision to install LED lights and you have reasonable proof, such as the loss of reception comes and goes with the lights cycling and absence of interference before these lights being installed.
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It also potentially pertains to equipment you bought and installed yourself which causes problems with your other devices.
The FCC regs require the person who installed the interfering equipment to resolve the problem, but they also require the manufacturer to have low enough tested emissions to make that possible.
 
George Stolz said:
So, in short, experiment blindly until it goes away. Thanks for the replies.
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Oh, no, not at all!
Experiment with a clear plan in mind, but realizing that there probably are no other tests you can do other than swapping components or adding filters. :)
It is true that when it goes away you can stop, though. :angel:
 
160928-1223 EDT

George Stolz:

You may not have to blindly use trial and error. But you may need to do some bench tests. Also we need everyone that encounters RFI problems with various devices to identify manufactures and specific devices that are a problem.

Note that any devices connected to a chopped sine wave dimmer will produce RFI.

See http://forums.mikeholt.com/showthread.php?t=174603&page=5 for my comparison of line current of one Feit LED model with a CREE and incandescent. This Feit model produced a lot of AM interference around 800 kHz. These are non-dimmed tests. Another Feit LEDs had about 50 kHz outputs. Because one CREE model did not produce RFI does not mean other models might not. But my limited tests would indicate a lower probability of problems with CREE than Feit. On the other hand I have had bulb failures with CREE and not with Feit, very limited sample.

.
 
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