LED / ham radio question

[AC0GV]

I'm looking for radio operators that have solved the LED RF noise problem. I'm running Under 100 watts and receiving weak signal stuff Not the local 100,000 watt FM broadcast station..
I need an assortment of 12-volt LED lamps that are RF quiet.
I assume that that means a brand that is polarity dependent AND 12 volts only. No 12 -24 volt.
I have that now and must run an incandescent over the operating location to hear even FM repeaters.
I always turn off the converter when boondocking, but the LEDs are still jamming things. In a campground there is no hope due to other campers. I need them for the RV, a communication shelter, and a home station, all are 12-volt only systems. BTW, the Scamp reading lights are RF quiet.TNX

[Raz]

It's not the LED itself that is causing the RFI issue but the bias circuitry. To eliminate brightness changes due to voltage variations, the LED's are typically powered by a switching supply, usually a current source. The switcher produces a wide band of harmonics most likely entering your receiver through one of the I.F. stages. Replacing the LED bulbs with incandescent bulbs is the simplest solution. Obviously efficiency is not an issue if you are running shore power. If you want to keep the LED's, I would try replacing the bias circuitry with a simple series resistor or perhaps a linear series regulator like the 78xx series.That would require purchasing LED's (the component) and adding your own circuitry. Note: a simple resistor bias will cure the RFI but unfortunatly your lights will now be voltage sensitive and less efficient. Most likely that's what the Scamp lights are using.

Unfortunately switching regulators are everywhere; your cell phone, your lap top, your flashlight, your tow. Even your electric toothbrush. And nothing is ever completely off.

[gordon2]

Rule #1. Dont buy cheap LED bulbs (Edit: Dont buy LED bulbs with cheap voltage regulators).

Unfortunately we also need rules 2-25 to solve this problem and I have not found them yet. I've been buying from SuperbrightLEDS.com and they usually sell better quality, but the one I got from them to replace the bulb in the new style Scamp reading light was the worst RFI offender yet. Returns are easy enough with them so trial and error might be rule # 2.

I would guess that maybe two percent of the members of this forum are concerned with RFI from their light bulbs bothering their ham radios. But 100 % of the members at ARRL would have a problem with LED bulbs at home or at camp at one time or another. I assume you are a member of ARRL since it is such a good resource:

http://www.arrl.org/files/file/RFI/Light_Bulbs.pdf
ARRL :: Technical :: The ARRL RFI Book 3rd Edition
Forum » RFI - Discussion and Q&A » LED light bulbs cause RFI
Radio Frequency Interference (RFI)

(This third link is to the forum.. perhaps a post there will elicit specific vendor or bulb suggestions)

[Larry C Hanson]

Hello,

One can build their own LED lights using LED strips from Ebay.
The strips can be cut up into 3 LED segments. Each segment
runs on 12VDC and has no active components so is very RF
quiet. Most any fixture can be converted by choosing how many
LEDs needed for the required brightness and wiring and gluing the
amount needed into the fixture. The strips work great on the old
fluorescent fixtures. In my old Trillium a couple of the original
fixtures were modified with just one little 3 LED strip piece and a
small SPST toggle switch providing ambient lighting at a cost of
70 ma. draw per fixture. Two provide plenty of ambient lighting.

Examples of Ebay Light Strip for sale:

https://www.ebay.com/itm/10pcs-50cm-...8AAOSwEzxYb0ae

https://www.ebay.com/itm/10pcs-SMD-5...UAAOSw8L5b86WF

The 'warm white' LEDs throw a nicer light than the white or cool white
because there seems to be less of the blue part of the spectrum emitted.

BTW one does not need the aluminum channel to mount the strips.
They can be glued onto the old metal fixture using JB Wed Quick epoxy.

LEDs are great but I still prefer to read using incandescent bulb using a
little AC halogen desk lamp converted to 12v by bypassing the transformer
and using a 7W landscape light type halogen bulb.

Uncle Larry

[Raz]

Originally Posted by gordon2

Rule #1. Dont buy cheap LED bulbs.

Actually, it's the cheap ones that use just a resistor to bias the LED. No RFI if theres no switcher.

[Jon Vermilye]

Originally Posted by Raz

Actually, it's the cheap ones that use just a resistor to bias the LED. No RFI if theres no switcher.

Agreed. While it may be difficult to find LEDs without built in voltage regulation, using them will solve the problem. They may create another one - most of the unregulated LEDs are not happy if your converter goes into equalization at 15+V. Still, the unregulated ones are cheap enough that replacing failures might make sense.

I have the same RFI problems with both my converter & solar controller when attempting to pull in distant FM stations. I've tried a number of filters, both at the devices & at the radio with no improvement.

[BatDude]

Some of the LED headlamps that are very high power/brightness have had to be set aside for our bat work. While one can see potential pit vipers while walking jungle trails the RF and sound interference has precluded virtually all ultrasonic recording of bats for a non-invasive means of surveys.


The noise swamps all sound signals below 30kHz- 35 kHz.


No longer have my HAM ticket, V31JU...never did get a US ticket when returning after 25+ years of living in the jungle.


Good luck with your quest. Most of us had to return to incandescent headlamps to not obliterate our acoustic data.



Bat Dude

[Darwin Maring]

Even the phone charger that plugs into the cigarette lighter receptacle in the car produced RF interference.

[AC0GV]

Originally Posted by AC0GV

I'm looking for radio operators that have solved the LED RF noise problem.

I ended up at Superbrightleds.com and after a long search found 2 types that were 12 volt only and a replacement for the 921 lamps, I order several of both. I found no 194 lamps that I liked. They did also have replacements for the old lamps that screw into a standard socket but are 12 volts. I wanted some for my shack project and could not find them. I'll report back about the radio noise when the WX gets warm. Highs this weekend are to be ZERO and below (f). To see my shack project, search ac0gv on QRZ.com or click on my "biography" in about me in this group.
Thanks for the leads.

[AC0GV]

Originally Posted by Jon Vermilye

I have the same RFI problems with both my converter & solar controller when attempting to pull in distant FM stations. I've tried a number of filters, both at the devices & at the radio with no improvement.

I just this past fall purchased TWO Bioenno Tech LLC / Bioenno Power SC-122420JUD Charge controllers. They are shipped for LiFePO batteries but there is a setting for SLA and I am using that on two sets of FLA batteries. So far, including winter field day it appears RF quiet. (mine were about $50 each.)

[redbarron55]

I bought cheap - no name - LED light fixtures and installed them all over the Scamp and have operated HF, VHF, and UHF with no issues. I have used NVIS antennas, vertical antennas and dipoles and no problems.
One field day I did have problems with a Harbor Freight inverter generator (the first 2500 watt Predator) that had hash and a EMI filter on the output took care of that.
Currently I am using an EPEVER MPPT solar controller with 300 watts of panels on the roof and have a PD battery charger/power distribution box still no problems with RFI.
Just Lucky I guess.

[redbarron55]

"The switcher produces a wide band of harmonics most likely entering your receiver through one of the I.F. stages."
Must be very very poorly shielded IF stages.

[AC0GV]

Originally Posted by redbarron55

I bought cheap - no name - LED light fixtures and installed them all over the Scamp and have operated HF, VHF, and UHF with no issues..

Yes, it seems to be a real roll of the dice. Some cause no trouble and others jam everything. My first house LED lights are now in an outbuilding and if I forget to turn them off they jam radios in the house. And my first charge controllers are now owned by non-hams.

[Raz]

Originally Posted by redbarron55

Must be very very poorly shielded IF stages.

Yes. Better receivers are dual or triple conversion with one of the IF frequencies at 455 khz. Most switcher run between 10 khz (some you can hear!) and 100 khz, putting harmonics right there. I have seen shielding on the front end and if the radio has a power supply it will be a well shielded switcher, but not much on the IF stages. With a narrow band and mV signals, I doubt designers worry about ambient noise.

[Raz]

Originally Posted by AC0GV

I ended up at Superbrightleds.com and after a long search found 2 types that were 12 volt only and a replacement for the 921 lamps, I order several of both.

I hope this works but I think you are going to find that these too will have switching drivers. Years ago I converted an old Coleman lantern to LED's. High output LED's and a series resistor. Superbrights used to sell the LED'S. Should you need to go that route, it's not hard to do.

[AC0GV]

Originally Posted by AC0GV

I'm looking for radio operators that have solved the LED RF noise problem.

Here are the LEDs that I ordered. First test has been with weak signal Am radio stations and they appear to be quiet. I also ordered 12V Low Wattage A19 Filament LED Light Bulb - 40W Equivalent that fits standard old RV screw-in sockets but they are backordered.

https://www.superbrightleds.com/more...t_review_email


https://www.superbrightleds.com/more...t_review_email