I have some more info I'd like to share that I learned after writing the
note below.
I have found the entire system to be very layout dependent with respect to
susceptibility to my transmissions. If I position things one way, my RF
doesn't trigger the switching circuitry. Yet, move things slightly and then
it does. I haven't been able to figure out any rhyme or reason to this
either.
Secondly, I tried once again experimenting wrapping the sensing line around
one of my torroids. This time I used a larger (about 1.5" dia) 77 material
torroid and wrapped about 16 turns of the sensing wire around it. It helped
with eliminating the RFI, but again, it was very dependent on where the
sensing wire was in relation to the switching unit, etc. But here is the
interesting part. With the torroid now wrapped, it is now acting as a
pickup for the sensing wire. I can now touch the torroid and the switching
unit will do its thing. All the wire on the sensing line is insulated so I
am not touching bare wire. The touch wire seems very sensitive. I am
wondering if using a small diameter piece of coax instead of the sensing
line will help things. I could ground the shield and attach the center
conductor to whatever is the touch surface.
But then again I am desperately grasping at straws here trying to find a
solution!
73,
Jon
NA9D
-------------------------------------
Jon Ogden
Sales Engineer
Cain-Forlaw Company
847-202-9898 (Voice)
847-202-9896 (Fax)
jon.ogden@cain-forlaw.com
> -----Original Message-----
> From: Jon Ogden [mailto:jono@enteract.com]
> Sent: Wednesday, June 27, 2001 9:40 PM
> To: rfi@contesting.com
> Subject: [RFI] Undercounter Touch Lights #4
>
>
>
> OK, more on the touch lights.
>
> These things are a pain. I am very close to giving up and
> convincing my
> wife to put switches in instead!
>
> Last night I worked on the hood lighting as mentioned
> earlier. I ended up
> getting it working with no RF interference by adding an
> additional torroid
> in the AC line very close to where it is plugged into the AC
> main. Last
> night it worked great.
>
> Now tonight it's not working. Getting into the lighting
> again on 20m. I
> have no idea why! Perhaps the moisture in the air has
> something to do with
> it? I have no clue. It is even getting into the lights when
> the touch line
> is completely disconnected from the hood. Previously, I didn't have a
> problem then.
>
> Anyone have any idea why things would work fine one day but
> not the next.
> Nothing has changed in any of my setups otherwise.
>
> I also took my oscilloscope and hooked it up to the touch
> line to measure
> the frequency. It turns out my scope isn't in the best of
> shape and is
> finicky. But it looks like the oscillation frequency of the
> dimmer unit is
> around 400 Hz. When I transmit on 20m, I end up getting a
> 284 KHz signal
> modulating the 400 Hz signal.
>
> I suppose if I could get rid of that it would clear things
> up, but I have no
> idea how.
>
> I am just so frustrated that it worked yesterday but not
> today. I am so
> close to just bagging it!
>
> 73,
>
> Jon
> NA9D
>
>
> -------------------------------------
> Jon Ogden
> NA9D (ex: KE9NA)
>
> Member: ARRL, AMSAT, DXCC, NRA
>
> http://www.qsl.net/ke9na
>
> "A life lived in fear is a life half lived."
>
>
> --
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>
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