[Chris Hornbeck]

On Tue, 15 Apr 2008 19:04:10 -0700, "Richard Crowley"
wrote:

"Eeyore" wrote ...

It is not the mains power that is earthed/grounded.
It is the RF input cable (from either the community
cable distro system, or from the TVRO antenna).

There's only ONE of those hence no possibility of a LOOP !

Good. We'll remember that next time someone comes
here asking about their HT system hum problem, and
why it goes away when they disconnect the cable. We
will let you explain to them that the hum is only in
their imagination.

This kinda thing is a large part of my day-gig these
last coupla years. I used to give the information away
free to our "installer guys" and now I get paid
(peanuts) to fix these issues myself. It's what in
America is called "early retirement". Arf .

Ground loops *do not* require a perfect non-conductive
loop to matter. Just the opposite, in fact. Modern consumer
electronics has many amazingly diverse sources of ground
contamination, and all include some element of current
into a "nominal" ground.

IOW, there are no "grounds". The difference between our
preconceptions of "ground" and the reality are the crux
of the biscuit.


Ground loops are systemic and subtle, and include the
summed parasitic couplings from all devices' mains to
each device's nominal Earth. It's a non-trivial summation.

Much thanks, as alway,

Chris Hornbeck