Beware of possible issues when installing some LED lights on your tractor

[aczlan]

Interesting the timing on this thread, I recently noticed that the LED backup lights I put in my car (drop in replacements that are 3x as bright as the incandescent bulbs that came out) mess with AM radio reception.
Fortunately, I am not in reverse for very long, but I can see it being frustrating.
Incidentally, the brake controller in the truck also messes with AM radio reception.

Aaron Z

 

[W8BYA]

I don't totally agree on the front end business. A tight, selective front end goes a long way to rejecting unwanted signal. We who used Motorola commercial FM rigs always laughed at the Hammy Hamster Rigs and their lousy front ends. We wouldn't have the RFI and intermod troubles that they did.

I am sorry to tell you again, that in this case you are wrong. You need to remember that the offending signal (the RFI) is directly on the same frequency that the radio is tuned to ! There is absolutely nothing you can do about it.

The situation would be analogous to you driving in your car yacking on your CB radio with another station a mile away.....alls great until a 3rd vehicle, with a CB also transmits and is only 500' away from you and on the exact same channel as you and your buddy.

That RF signal from the 3rd car is going to over power your friend a mile away and because everyone is on the same channel you have no choice but to listen to that new interfering station. Hope that makes sense. No filter in the world is going to eliminate that other (offending) signal if it is being generated on the same frequency that your receiver is tuned to.

 

[W8BYA]

Interesting the timing on this thread, I recently noticed that the LED backup lights I put in my car (drop in replacements that are 3x as bright as the incandescent bulbs that came out) mess with AM radio reception.
Fortunately, I am not in reverse for very long, but I can see it being frustrating.
Incidentally, the brake controller in the truck also messes with AM radio reception.

Aaron Z

Good catch Aaron. Like you said good thing it's only in reverse.

 

[Industrial Toys]

I am using low Tier Motorola Radios around here for communications. VHF. They are troubled by the noise of the E-Gator, even getting by the DPL. But everyone knows the radios were built for a certain market and have lousy front ends. I would be curious to grab a high Tier radio and see what it does. My thinking? A little noise on freq, it can handle. A lot of broad spectrum noise with an unselective front end, and it's swamped. I could be wrong. But I do know for a fact, that good radios are often not bothered by RFI that would incapacitate a cheap radio.

 

[radios1]

I am using low Tier Motorola Radios around here for communications. VHF. They are troubled by the noise of the E-Gator, even getting by the DPL. But everyone knows the radios were built for a certain market and have lousy front ends. I would be curious to grab a high Tier radio and see what it does. My thinking? A little noise on freq, it can handle. A lot of broad spectrum noise with an unselective front end, and it's swamped. I could be wrong. But I do know for a fact, that good radios are often not bothered by RFI that would incapacitate a cheap radio.

better radios also use very effective powerline filtering, and shielding!.. the best way to stop RFI is to keep the RFI contained inside the metal enclosure for the SMPS..

 

[atitus74]

But I do know for a fact, that good radios are often not bothered by RFI that would incapacitate a cheap radio.

Its possible its just ignoring the noise rather than actually blocking it. The nicer radios you are talking about might be digital. In that case the signal is encoded and can have error correction resulting in much better call quality vs analog in noisy RF environment. Like the previous poster mentioned though the signal still needs to get there. If there is something causing the signal to get attenuated while it travels through the air there is nothing you can do to fix that.

 

[atitus74]

This isn't a new thing with LED's. I remember when anything that used a power adapter including cell phones used to come with the "wall wort" block transformers. When they first started changing over to switching power supplies, they were really bad with interference. Even expensive phones like iPhones had this problem. If my wife plugged in her iPhone to charge anywhere in the house, you would get horrible noise over the radio, baby monitors, etc. They corrected it with higher quality adapters but those early ones were crap.

 

[W8BYA]

I am using low Tier Motorola Radios around here for communications. VHF. They are troubled by the noise of the E-Gator, even getting by the DPL. But everyone knows the radios were built for a certain market and have lousy front ends. I would be curious to grab a high Tier radio and see what it does. My thinking? A little noise on freq, it can handle. A lot of broad spectrum noise with an unselective front end, and it's swamped. I could be wrong. But I do know for a fact, that good radios are often not bothered by RFI that would incapacitate a cheap radio.

I appreciate your comments & input but IMO we are veering off course from the direction I want to go. I do not think this is the right forum to get into receiver design, possible IMD issues, S/N, effects of in-band & out-of-band signals, and a bunch of communications theory. I guess you could start up a new post.

If you were to ask me for advice I would say that you may have different issues than what I have going on here. Also, until you connect up a spectrum analyzer to your setup and identify & characterize all of the signals entering your radio via the power-lines, signal/control lines, speaker lines, and antenna port you are sorta "shooting from the hip". You may be making assumptions that may or may not be true. I mean that in a polite way but w/o measurements you really do not know what you have going on there. Also IMO you need to be very careful when you use a term like "broad spectrum noise". You must identify what you mean by that as that phrase can come in LOTS of different forms with different effects.

My issue is that of confirmed high-level carriers which are direct harmonics of the 477 kHz oscillator used in the SMPS of my LED light fixture. I have verified that the harmonics are emanating the fixture in the form of conducted emissions. I have also verified that these harmonics are on the exact frequencies as the AM & FM stations I want to receive. In other words these high-level carriers are in-band (or on-channel) interfering signals.

My issue is NOT due to front end overload or IMD issues but direct reception of carriers on the same tuned frequencies I need to receive. As soon as I get some more data from my filtering tests I will post the results in the hopes it may help others.

What I should do is take the spectrum analyzer outside and measure the conducted RFI on the DC power-lines directly at the radio. And then connect the tractor antenna to the spectrum analyzer to see the level of these harmonics that are actually being radiated by all the power-lines and harnesses in the tractor. I think that would be interesting and help me determine if the RFI is entering the radio via the antenna port or power-lines.

Finally, recents tests have provided some good news by verifying that not all LED light fixtures are RFI trash makers. So there is hope

 

[k0ua]

Finally, recents tests have provided some good news by verifying that not all LED light fixtures are RFI trash makers. So there is hope

I have recently replaced the 4 foot fluorescent tubes in my garage and kitchen with these ballast bypass single end powered LED tubes. Just chop out the old ballast and rewire for one end 120 volt AC power on the two pins on one end of the tube. They work great, and I cannot find any RFI out of them. So a win win. Saving electricity over the old 40 watt tubes (18 watts per tube for the LED's), considerably more light, and No RFI. I was a happy camper.

https://www.amazon.com/Hyperikon-Si...d=1574275494&sprefix=hyperikon,aps,201&sr=8-7

 

[Industrial Toys]

I appreciate what you are saying, but it is a two way street. FCC says that specifically, mentioning BOTH the issues with Generating AND Receiving unwanted noise. So maybe it would be just as prudent to ask, what Receiver people are having trouble with. I bet in most cases it's designed with as much thought and "care" as the lights. You may not remember days gone by when Hams would go to their neighbors and make modifictions to their receiving equipment to reduce RFI.