On Sat, 16 Aug 2008 15:07:55 -0400, Gary Hoffman wrote:
>You know that many noise filtering circuits (for power lines, ethernet, RF
>and etc) use circuits the one half of which is connected to ground. Remove
>an effective ground connection and you degrade the performance of those
>circuits.
WRONG! This is one of those confusions we have about multiple uses of the word
"ground." A filter does NOT in any way depend on a connection to EARTH to
operate. What it DOES need is the connection of SHUNT ELEMENTS to CIRCUIT
REFERENCE or the shielding enclosure. For example, when the filter as at the
noise source, that connection should be to the shielding enclosure or circuit
reference of the noise source. When the filter is at a RECEIVER, that
connection should be to the shielding enclosure or circuit reference of the
receiver. But EARTH has NOTHING TO DO WITH IT!
There is an excellent discussion of this in reference texts by Henry Ott and
Clayton Paul. Google to find them. The popular myths about connections to
earth solving RFI problems are WRONG!
73,
Jim Brown K9YC
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|