A 500pF cap (around 40 ohms @7.5MHz) rated for 230Vac would also work in an
X configuration for differential noise. The cap will be usefull also in a Y
configuration if common mode noise is the problem, or a free sample power
filter from Cor.com or SAE or Shurter.
X-configuration means from phase to nuetral. 1-cap
Y-configuration means from Phase to earth ground and Nuetral to earth
ground. 2- caps
Michael Findley, NCT
Compliance Engineering
512-683-8797 office
512-683-8880 FAX
ke2n@cs.com
Sent by: To: RFI@contesting.com
rfi-admin@contes cc:
ting.com Subject: RE: [RFI] Nighthawk CO2
Detector
08/19/2002 10:32
AM
They have a web site where you can ask a question, although its unlikely to
be fielded by an engineer ...
http://www.kiddesafety.com/kiddesafetycorp/contact.html
The company would probably be happy to sell you a battery powered version
of the same thing - that should be inherently more immune
Ken
PS - we suppose you mean CO detector, not CO2 detector....
>
>> -----Original Message-----
>> From: Chuck Gooden - N9QBT
>> I am having RFI problems with a Nighthawk CO2 detector when I operate on
40
>> Meters. ?Does anyone have any Ideas on how to get rid of this problem.
>>
>> I am planning to try a Ferrite core on the AC Line (hot lead only)
inside the
>> electical box as soon as I can get some but any other ideas would be
welcomed.
>>
> ? ?If the signal is coupled to the line in differential mode, then this
might work although in in-line coil would work better; but usually it's
induced common mode onto the line. ?If it's common mode, then you need to
wrap the whole power cable (hot, cold & grd) onto a ferrite. ?Here's a
diagram (hope it comes through OK):
>
> ? ?Differential Mode:
> ? ? ? ? ? ? ? ? ?induced signal path ----->
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?______________________
> ? ?AC POWERLINE ______________________
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? <-----
>
> ? ?Common Mode:
> ? ? ? ? ? ? ? <----------
> ? ? ? ? ____________________
> ? ?AC ____________________
> ? ? ? ? ? ? ? ?<----------
>
>> The CO2 Dector is Model KN-COPP-3, Assembly #900-0076, Manufactured 17
April
>> 2000.
>>
> ? ?Be sure to contact the mfr to let them know about the RFI problem.
Usually, telling customer service is a waste of time. ?Find the people who
care about such problems (if they even exist!).
>
> ? ?73,
> ? ?de ed -K0iL
>
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