[RFI] Fluorescent Light RFI

Mike King - KM0T scsueepe at mtcnet.net
Thu Oct 25 10:28:03 EDT 2012

Jim, thanks.  

Yup, those are a problem too.   You probably know this, but the only
solution I can offer right now is to try and find "magnetic ELV
transformers" and stay away from the electronic ones.  Not an easy thing.  I
will keep my eyes open and take a look here when I get some time.  Its been
some time now since I have seen them offered as the drivers.  Perhaps ebay?

One thing I did here was to eliminate the driver altogether, found out the
voltage of my LED strip light and fed it with a 12V dc power supply, problem
solved.  In fact, the cheapo power supply I used had a tap switch for 6V, 9V
and 12V.  So I can kind of dim them to those voltage levels, worked pretty

For some task lighting and picture lighting with MR16 lamps, the thing I
have done is to stay with 120v fixtures, where the MR16 lamp would then need
a GU10 base (120V), not the base that takes 12V.  This of course eliminates
the low voltage transformer.   These incandescent MR16s of course dim real
nice with dimmer panels or wall dimmers.  But they get really hot and have
short lamp life.  

I am currently experimenting now with a LED replacement GU10 base lamps as a
replacement for the incandescent (halogen) MR16.  The problem is for a 50W
equivalent to the incandescent MR16, the LED version puts out about 400
lumens less in light. (more like a 20W MR16)  But since the beam is much
more controlled, the output does not appear to be much less.  No RFI from
what I can tell so far for the one I have a sample of, and dimmable.  Not
quite on the market yet, waiting for technology to catch up with what we
need.  It is coming, but not yet.  I had a MR16 LED from home depot that I
tried, was not dimmable.  No apparent RFI, but acted pretty strange when I
tried to dim it.  In fact it stayed full output until the other incandescent
MR16s were nearly off...wide input voltage tolerance.

I have Lutron wall box dimmers as well as Crestron 6 channel dimming
modules.  These appear to be about the best you can get.  I don't believe
they are contributing to my local RFI, but I have some work to do there yet.
Cheap wall box dimmers are an issue.

Again, I will see if I can come up with anything.  Hope I can contribute a
bit here that may help.


Mike King, PE

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Thursday, October 25, 2012 8:46 AM
To: rfi at contesting.com
Subject: Re: [RFI] Fluorescent Light RFI

On 10/25/2012 5:29 AM, Mike King - KM0T wrote:
>   Be
> ready.  Its not going to be pretty.    I long for the magnetic ballast and
> incandescent lamps days

Thanks for your excellent and detailed post. As a retired designer and
specifier of sound systems for public buildings, I appreciate your struggle
with the process.  I regularly ran into similar "do it cheaper" 
contractors bidding for the systems I designed.

  I'm sure you're aware of the issues with the use of switching power
supplies for low-voltage lighting fixtures. Here in northern California,
there were many of them in the home I bought here, and I've not been able to
find replacements that are not noisy, and a transformer won't fit in the
backbox.  Electrical supply stores sell nothing but un-labled "electronic
transformers."  Can you offer any advice in this area?

73, Jim K9YC
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