question for electronic gurus (RF noise)

[Bavafa]

I am in the process of installing HID light and experiencing some unwanted RF noise in my Radio. I have not tested Nav and other instruments to see if there is any affect of this HID, but there is definitely some RF noise when receiving radio calls.

I have installed some ferrite core to have no affect and installed a .1uF capacitor with no affect.

- The question are, is there any more effective use of ferrite core then just passing the two lead wire (+/-) thru it, as oppose to passing the wire thru the same core a few times?

- Can I use an inductor (possibly 100uH) with the capacitor to cut down the noise and if so, do they need to be in series, parallel or any other configuration that is more affective.

I have got some what overwhelmed with the amount of info in wikipedia and Google specially that I know next to nothing about electronics

As always, appreciate all comments and suggestions.

[Mike S]

George (Hals buddy) is pretty good with electronics, as I recall, check with him.

[Brantel]

I had noise as well that was totally eliminated by passing the + & - wires thru the core three times. The more times you pass it they, the more it will block RF. This needs to be done as close as possible to the HID ballast. The capacitor would then be installed across the power leads to decouple whatever gets past the core.

What kind of core are you using? What kind of capacitor ?

[Bavafa]

Hi Brantel
First thanks bunch for all the pervious information you provided on the HID.

The core and capacitor that I was using is from Radio shack snap choke core http://www.radioshack.com/product/in...ductId=3012599
and this capacitor http://www.radioshack.com/product/in...ductId=2103630
which seem to have hardly any affect. This chock is not as big so couldn’t wrap the wire around it so I have put three of them in a raw but I found a bigger one that I should be able to wrap the wires around it.
I also saw and got this inductor
http://www.radioshack.com/product/in...lickid=prod_cs
but not sure if I should put it in series with the capacitor or parallel.

[DBone]

Look at this thread: http://www.vansairforce.com/communit...ad.php?t=63836

These little RFI filters might help depending on the connections involved. Good luck!

[elippse]

In order to engineer an EMI-RFI reduction scheme it is necessary to know the physical placement of the components relative to the input power source. Where is the HID power supply located and is it next to the lamp or some distance away? Is the power to the HID a twisted pair in a shield or unshielded wires? Having a better idea of the physical layout and the type and size of wiring allows much better planning and success. Capacitors and chokes incorrectly used can actually add to the problem. No component should be added unless it is understood exactly how and what it will do.

[molson309]

The largest source of RF noise in my HID setup was the cable between the ballast and the lamp. I do not have the type of lamp with the high voltage module as part of the lamp assembly. I could tell approximately where the noise was coming from by using a handheld aviation radio as a probe.


Slipping braid over the cable between the ballast and lamp significantly reduced the RF noise generated when the lights were running. Before the change the handheld squelch would open within a few feet of the lights (one in each wingtip). Afterward I had to place the handheld within a few inches of the lamp to hear any noise. Also, the noise was stronger while the lamps were warming up.

Mark Olson RV-7A F1-EVO Rocket

[Brantel]

I doubt that inductor choke has enough power handling capability to work properly in this situation....

If you are going to use an inductor, here is how it should be connected:

Originally Posted by Bavafa

Hi Brantel
First thanks bunch for all the pervious information you provided on the HID.

The core and capacitor that I was using is from Radio shack snap choke core http://www.radioshack.com/product/in...ductId=3012599
and this capacitor http://www.radioshack.com/product/in...ductId=2103630
which seem to have hardly any affect. This chock is not as big so couldn?t wrap the wire around it so I have put three of them in a raw but I found a bigger one that I should be able to wrap the wires around it.
I also saw and got this inductor
http://www.radioshack.com/product/in...lickid=prod_cs
but not sure if I should put it in series with the capacitor or parallel.

[cfiidon]

Brantel is right on.

An inductor (sometimes called a choke) appears to DC current as a short, but to RF energy provides a "resistance" to the changes in amplitude. It does this as the changing magnetic field induces a "back" current.

A capacitor on the other hand appears to DC as an "open", but to RF appears at a short. A bit more complicated than that but a good way to think of it.

Don

[Mike S]

Although I am always open to new info, all this technical stuff has choked my capacitance for new learning, and I find I am having a certain resistance to comprehension.

Probably my brain circuitry has developed a short