[RFI] Cree LED Light Bulb

Joe Mesh jm at drsmesh.com
Mon Aug 11 17:13:19 EDT 2014

I have never had any RFI traced to a LED or a CFL - even a dimmable LED
dimmed passes my noise evaluation!   I just never found any noise.

The problem with CFLs (beyond being ugly!) is that they make heat and they
do not have the very significant ROI of the LED lamps.    CFL life is also
dramatically shorter.    I just replaced 224 FL40s, 35 PAR30s, 12 PAR20s and
12 MR16s all with LEDs.    CFL current savings is ~30% whereas the LED
savings is ~80%.    These LEDs are all cool to the touch including the
bases.    This means added savings with reduced HVAC load.  

Joe / W8SS / Mesh Engineering / 810-629-5500
AKA: Dr. Joe Mesh, D.M.D., C.A.G.S. (Prosthodontics) 
from beautiful downtown HELL, Michigan 
Always available at:   info at drsmesh.com 
See us on the Web at:    drsmesh.com 

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Dale J.
Sent: Monday, August 11, 2014 4:39 PM
To: rfi at contesting.com Reflector
Subject: Re: [RFI] Cree LED Light Bulb

I've had several modern day CFL's fail.  Just the other day one in the
basement which is on 24/7 went out.  I thought I had a bad socket as I
unscrewed the light and back in again, it started up on for a few seconds
but then went out.  I changed out the CFL with another CFL, same size and
it's still working.  The CFL's that have failed have signs of overheating
even though I have them in well vented fixtures.  A couple of the failed
CFL's developed loose glass, but weren't cracked just loose.  I also
dissected one too, curious what's inside.  I found an IC, some resistors and
capacitors mounted on a PWB.  I have not noticed any RF noise from any CFL
and we have quite a few around the house.  I must say it takes a couple
years for them to fail and several are on all the time.  I have two in the
shack in Luxo bench lamps, well vented at the top.  They are inexpensive and
I'll continue to use CFL's until something better comes along for about the
same cost.  

If I recall, the mfg of one brand of CFL stated that they should be used in
an upright configuration, I take it to mean the heat will rise away from the
electronic pod below the glass. Maybe makes sense, but in my use most of the
CFL's are upside down so any heat generated from the glass will go into and
around the electronic pod base, perhaps shortening it's life, just a guess.

Dale, k9vuj

On 11, Aug 2014, at 13:38, Jim Brown <jim at audiosystemsgroup.com> wrote:

> On 8/11/2014 11:05 AM, Charlie Gallo wrote:
>> Again,  you're  looking  at  1.17  watts of light, and therefore 
>> 12.83 watts as heat
> All good analysis, quite sufficient as far as fire hazard is concerned.
But there's another issue -- that 13W of heat has to go somewhere, and
depending on the enclosure, some or all may stay within the enclosure and
raises its ambient. That may, or may not, allow sufficient conduction of
heat away from the circuitry to prevent destructive failure of the lamp
and/or its circuitry.
> Something like 5-6 years ago, I bought a couple of Edison-base multi-LED
lamp assemblies from a hamfest vendor, and stuck them in a simple reflector
fixture (one-third spherical, thus 2/3 open) as lighting in the shack.
Within a month or two, both lamp assemblies had developed cracks in the
> 73, Jim K9YC
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> RFI at contesting.com
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