[RFI] Lutron Eco-10 Fluorescent dimming ballast?

Jim Brown jim at audiosystemsgroup.com
Thu Apr 14 15:42:05 EDT 2005

On Thu, 14 Apr 2005 11:57:21 -0700, Leigh L Klotz, Jr. wrote:

>Alternatively, does anybody know of any fluourescent ballasts with good 
>EMC to specify?

Several thoughts. 1) Part 18 is a joke for emissions. 2) Electronic dimmers 
work by chopping at some frequency at roughly 40-60 kHz, and I would expect 
them to be dogs for HF RFI. Expect lots of harmonics. Some are also dogs at 
VHF and UHF, where they cause problems with VHF and UHF wireless mics. 

Several years ago at a trade show, I spoke with a Lutron engineer who assured 
by that they had stuff that met Part 15 Class B, but when pressed for 
documentation and a part number, I never heard back from them. 

BTW -- these systems will also wipe out the IR remote controls used by most 
home entertainment products, because the fluorescent lamps have spectra in 
the same range that the IR units use to talk to the equipment that they 
control.  They cause also interference to the older IR equipment used for the 
hearing impaired. The equipment that gets hit the hardest uses an IR 
subcarrier of 95 kHz. Never stuff works around 2.3 and 2.7 MHz, and has no 
problem. The IR remote control stuff is all in the 60-100 kHz area. 

I would approach this entire project with great caution. Unfortunately, I do 
not have data on specific makes and models. Several years ago, I did chase 
down a mfr of good ballasts and dimmers without VHF/UHF RFI, but, alas, they 
went through a corporate reorganization and I lost track of them. Their engr 
was a ham, and knew his stuff. 

Jim Brown  K9YC

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