[R-390] OT? Dimmer buzz, solution?

[JMILLER1706 at cfl.rr.com]

Sorry for the duplicate posts, but here's one more idea:  Get the ARRL 
RFI Handbook.  Apparently it has circuit designs.   See 
http://lists.contesting.com/archives/html/RFI/2000-09/msg00015.html

"> (b) I need to know how to modify a light dimmer switch to reduce
> the RF emission. Any circuit diagrams that anyone has, or can 
describe, I
> would appreciate.  How does one quite a noisy SCR? There are three 
primary
> noise sources which I have located with DF.
> 
        Light dimmers & speed controllers as well as touch lamps both
benefit from the use of brute force AC-line filters and ferrites added 
to
the lines.  But they don't always work.  Sometimes you need to replace 
the
devices with quieter one that has built in RFI suppression.  The ARRL 
book
recommends the AC filter and ferrite approach, using an FT-240 or FT-140
sized core with about 15 turns on it.  I think 43 mix material for 
HF/VHF
noise and #75 or 'J' mtrl for lower HF noise should be used.  It may 
take
two cores to get the noise down low enough, but then you run out of AC 
line
so an electrician may be needed to install additional wiring.  Also on
dimmers you may need  cores on the input and output.

        In the case of touch lamps, especially ones radiating, a 1-4 
Kohn
resistor and a 10 microHenry choke on the sense line may help as well.
Again, do these mods at your own risk or have an electrician do it to 
reduce
your liability.

        I've also found that plugging these lamps into different outlets
makes the noise less resonant on some freqs and more on others.  If your
lucky, it'll move to a non-ham freq!

"

----- Original Message -----
From: Dave or Debbie Metz <dmetz at ntelos.net>
Date: Friday, July 1, 2005 10:21 am
Subject: [R-390] OT?  Dimmer buzz, solution?

> While this is probably not within the parameters of heavy iron, I 
> do have a 
> question for the collective wisdom of this esteemed group. I have 
> been 
> haunted for years by lamp dimmer buzz radiated as RF that gets 
> picked up 
> with my basement hobby an the AM that the R-390 wants to hear.   
> Recently, 
> I purchased a Lutron Lamp Debuzzer Coil  LDC-10-TCP in another 
> attempt to 
> eliminate this radiated hash. Low and behold the $110 investment 
> worked 
> fantastically!  Now what I want to know is how to build such an 
> animal for 
> a lot less than $110!   All there is to this is a box about the 
> size of a 
> smaller ballast transformer with two wires. It goes in series 
> between the 
> dimmer and the light load. They have very specific amperage 
> ratings , 
> 400-600 watts, 600-1200 watt, and 1200-1920 watts depending upon 
> the needed 
> load range.  It sure is great to now have the XYL upstairs 
> watching TV with 
> a dimmed light and I can listen to the DX BC band on the 390!  
> There has to 
> be a cheaper solution for the rest of my dimmed light circuits.
> 73's
> dave
> 
> 
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