On 12/9/2013 1:11 PM, Rick - DJ0IP / NJ0IP wrote:
I have read lots of stuff on grounds and it appears to me that there is
nothing than anyone says or writes that isn't contradicted by someone else,
elsewhere.
Bill Whitlock, Chair of the AES Standards Committee Working Group on EMC
(I am the vice-chair) laid it out quite well. You can study the
extensive tutorial material on his Jensen Transformers website. I've
adapted his analysis and models to what happens in the ham shack. You
can see it in the Power Point pdf on my website under the topic of
Interfacing.
k9yc.com/publish.htm
The mechanism that puts AC buzz in our audio is power system leakage
currents. It has NOTHING to do with a "loop." Those leakage currents
flow on the green (ground) wire, and the resulting IR drop causes every
chassis to be at a somewhat different potential, and that potential
consists of the triplen harmonics of the power frequency. The difference
between those two ends of an unbalanced connection is simply added to
the signal. The interfacing tutorial shows this, and shows simple,
inexpensive solutions.
73, Jim K9YC
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