LED VHF interference

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Plevier

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I have an LED chart table light like this one http://www.boatelectricals.co.uk/ma...6-100100-chart-light-led-10v-30v--chrome.html

It's fine when it's in "standby" with just the one red LED on but when turned on with about 18 white LEDs lit it causes bursts of interference on the VHF (Raymarine 240) that you can't kill with squelch. I also have a masthead LED tricolour (Lopolight) which is right next to the aerial, that causes very slight interference but that is easily dealt with by turning the squelch up one click.

As the chart lamp is a long way from the antenna but only cm from the radio and is the interference is un-squelchable, I'm hoping it is cable born rather than radiated. I can easily get at the light's wiring and put it through a ferrite ring or clip-on, and easily extend it if it needs several turns round a ring. Is this likely to work, and what sort of ferrite should I use? There is a bewildering variety on ebay!

Thanks.
 
Hallo Plevier.
I have the same problems. My LED lamps are " multivolt" types.
10 to 30 volts.The build in converter has to feed the LEDs in the
mode of constant current and the switch frequency is very high,
therefore the trouble onVHF radio.
I checked it by a voltage regulatet supply and learnd : when the
supply is about 9 - 10 volts , then the interference will become very little.
I soldered in the feed line to a lamp of about 3 watt a resistor of ca. 10 - 20 ohms.
You have to try.I have a 12 volts system. In a 24 volt System you need ca.
50 - 80 ohms. As the current is low , ca. 0.2 - 0.3 amps , the power of heat
in the resistor is low.
Try and be sucsessfull.
Greetings
Hermann
 
Last edited:
Regarding type of ferrite to use. I think most ring types are suitable. I found that old computer gear is a great source of ferrite rings. ie on the keyboard cable just inside the keyboard, in some connector cables or in an old printer but best source is a compute power supply where there are various rings mounted also some slugs witha coil around will also do. Another source of ferrite is an old transistor radio where the black ferrite rod usually a few inches to 10 inches long has a coil on it. It can be broken to the length you need and just wrap your feed wire around the ferrite. It doesn't have to be a ring.However as said a capacitor used in conjunction will also improve the isolation of the popwer supply in the LED to the radio.
good luck olewill
 
HermannLenz said:
Hallo Plevier.
I have the same problems. My LED lamps are " multivolt" types.
10 to 30 volts.The build in converter has to feed the LEDs in the
mode of constant current and the switch frequency is very high,
therefore the trouble onVHF radio.
I checked it by a voltage regulatet supply and learnd : when the
supply is about 9 - 10 volts , then the interference will become very little.
I soldered in the feed line to a lamp of about 3 watt a resistor of ca. 10 - 20 ohms.
You have to try.I have a 12 volts system. In a 24 volt System you need ca.
50 - 80 ohms. As the current is low , ca. 0.2 - 0.3 amps , the power of heat
in the resistor is low.
Try and be sucsessfull.
Greetings
Hermann
Click to expand...

Knowing nothing about electrics -& having the same problem- can i ask if there is an increased current consumption doing this?
 
@ Plevier.
The unit you use is a quite expensiv one , I think. I use cheapests China LED's.
Ba 15d and E14 , in a stock of 10 only 3-4 € each. 3 watt types , warm white.
Current is about 0.2 - 0.25 amps at 13 volt and 0.3 - 0.32 amps at 9 - 10 volt.
The problem is the little electr.switching box. In the very narrow space in a boat ,
I think so , it is better to use no box. Only a solution with a resistor will help.
In the steering house all the Led' s are driven only by a resistor without the box.
In the saloon ( of my 34 ft wooden motorboat ) I use box and resistor.
But there are two 3 watt Led's bought by "marblue" , ca.20 € each .There is no interference to VHF or UKW Radio.
But : the cheapest China is the best for the " experimental" skipper.
Greetings to Brighton and the whole World.
Hermann
 
Daydream believer said:
... can i ask if there is an increased current consumption doing this?
Click to expand...

Using a series resistor on an already regulated LED will cause the regulator to try to keep the output the same, which will cause an increase in current. At the point that the input voltage drops below the threshold of the range, the light output will start to decrease. I think it's a poor solution.
 
The problem is that the manufacturers use buck regulators that oscillate at a speed which interferes with transmissions at 30 - 300 MHz.

I've written about it before:
http://www.saltyjohntheblog.com/2012/01/vhf-radio-interference-from-leds.html

It's also a problem with some 240v LED lights - people with digital hearing aids, for instance, report issues.

I hope the manufacturers are on the case, but they're moving very slowly.
 
Salty John said:
The problem is that the manufacturers use buck regulators that oscillate at a speed which interferes with transmissions at 30 - 300 MHz.

I've written about it before:
http://www.saltyjohntheblog.com/2012/01/vhf-radio-interference-from-leds.html

It's also a problem with some 240v LED lights - people with digital hearing aids, for instance, report issues.

I hope the manufacturers are on the case, but they're moving very slowly.
Click to expand...
With the cheapo eBay buck/boost I've found a capacitor each side cleans it up OK, using a degen ssb receiver next to the regulator and scrolling through frequencies. Can't remember what size cap though.
 
I had a USB cigarette lighter plug in thingy. I used i to charge the iPad.... it wasn't until I noticed we had not had a VHF wether forecast all day, that I realised it was totally killing the reception of the VHF... no interference at all. Just no reception..!!! Be warned.
 
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