On Mon, 20 Aug 2007 16:50:54 -0700, Jim Lux wrote:
>For folks looking for ways to provide galvanic isolation (which
can
>help with pin 1 problems),
You don't need DC isolation to prevent pin 1 problems. All you
need to do is connect the cable shield to the shielding enclosure.
What could be simpler (and cheaper)?
This whole myth about the need to separate "RF ground" from "audio
ground" from "control ground" to prevent "ground loops" has caused
us lots of un-needed grief. So has our reliance on unbalanced
interconnections.
There's a section in my RFI tutorial that outlines a very simple
station layout that virtually eliminates power-related hum and
buzz on unbalanced interconnections between boxes in our ham
shacks. http://audiosystemsgroup.com/RFI-Ham.pdf
The executive summary is that in addition to pin 1 problems, 1)
hum and buzz is due to IR drop from noise current on the shield;
2) we simply need to minimize the hum/buzz noise voltage between
that equipment by plugging all of the power supplies into the same
grounded outlet; and 3) we can further minimize the IR drop by
using interconnect cables with beefy copper shields. When you need
multiple power circuits (for an amp, etc.) simply put all of those
circuits in the same AC quad box.
73,
Jim Brown K9YC
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