[RFI] Common Mode Line Filter

David Cole dave at nk7z.net
Mon Aug 11 09:39:11 EDT 2014


Hi Jim,
Thanks for the expansion on that...  I know less than I want to know
about Power Line...  Any way you know of, that a power company will go
along with, to clean up power as it arrives?  Ferrite's on the power
lines etc?  I am almost afraid to ask the power company about adding
ferrite's to the incoming lines.
-- 
Thanks and 73's,
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On Sun, 2014-08-10 at 22:15 -0700, Jim Brown wrote:
> On 8/10/2014 10:03 PM, David Cole wrote:
> > Which forces me to ask...  What does the power company call common mode?
> 
> The voltage between neutral and green.
> 
> Thanks to a "Pin One-Like Problem" in most equipment, common mode often 
> trash leaves equipment on the green wire, which radiates it. The Green 
> wire SHOULD be bonded to the chassis at the point of entry, but it often 
> is not. Instead, it goes to the circuit board, and may eventually find 
> the chassis. Sometimes it fails to hit the chassis because paint is in 
> the way. This is "The Pin One Problem."
> 
> In virtually all commercial line filters, the green wire bypasses the 
> filter, so the filter does nothing to kill common mode current.
> 
> 73, Jim K9YC
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