[aprssig] TAPR Dayton Solar Talk

Stephen H. Smith wa8lmf2 at aol.com
Mon May 30 23:26:01 EDT 2011

On 5/30/2011 7:18 PM, Jim Sanford wrote:
> All:
> I, too have suffered the premature failures.  So many, that on top of the 
> onerous mercury disposal rules, I'm over CFLs -- bought a lifetime supply of 
> incandescents while I could, and slowly converting to LEDs   Adding insult to 
> injury, the CFLs are very RF noisy -- so noisy, that my X-10 remote controls 
> can turn one on, but never off, not matter how much filtering I put in 
> upstream of the noise generator.
> //

I've had the same issues with X-10 controllers, both from CFLs and some 
switching power supplies.  The "magic" fix I've  I've found is ferrite-core 
inductors in series with the offending lamps.

When X-10 modules or wall switches go bad (they tend to pop with lightning hits 
on the power grid), crack 'em open.  Each one has a 1/4" dia ferrite rod about 
an inch long, wound with turns of #18 enameled wire - it's an EMI choke.   
Remove this inductor and place it in series with the hot conductor of the line 
going to the offending power supply or lamp, either inside the lamp fixture or 
in a short male-to-female extension cord.    Or cram them inside an outlet 
strip that the offending devices are plugged into.    Works like magic to stop 
the noise issues.      The 100uh RF chokes that are a standard item at Radio 
Shack also work, but they are wound with much finer wire - suitable for a 
single CFL but not much more.

If you want a rather pricey solution, the original Tripp-Lite "Isobar" surge 
suppressors (the ones that have regular household double outlets in an extruded 
aluminum housing -  not the cheap consumer ones in plastic housings) are 
incredibly effective.  These devices actually have honest-to-god  pi-network LC 
RF low-pass filters made with ferrite toroid inductors and silver-mica caps in 
them, in addition to the usual MOVs found in most so-called surge suppressors.  
Each pair of outlets is isolated from it's neighbor(s) by such a network.  You 
can plug an electric drill, a small refrigerator or a high-power laser printer 
into one outlet pair and a PC in to the next pair and not get random reboots 
from motor starting transients.  On the "8-holer" (four double receptacles) the 
final pair farthest from the power cord end has FOUR of these pi-networks in 
series for 90-100 dB RF attenuation at 1 MHz.

I find them invaluable on field day to stop the AC line running to the 
generator from becoming a counterpoise for vertical and half-assed end-fed wire 
antennas. And they work in the other direction to stop electrical hash and 
ignition noise from the generator from conducting up to the operating position. 
    They also stop all kinds of EMI/RFI problems at home, caused by ham shack 
RF backing up into the household wiring when using end-fed unbalanced HF 
antennas - just plug all the ham-shack power strips into the last pair of 
outlets (the one with the most filtering) on the Isobar, and then plug the 
Isobar into the wall.



Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

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