The shielding enclosure of most electronics is a reasonable ground
reference. A 747 has no connection to earth, but the shielding on its
wiring works just fine.
And even if that receiver had a 2-prong plug, the path from the
receiver to earth is likely to be some significant fraction of a
wavelength away from earth. If it happens to be some odd multiple of a
quarter wave at some frequency, it will look pretty much like an open
circuit at that frequency.
The principal reason for that 3-prong plug is to provide a safety
ground for the equipment, both to prevent a shock hazard, and to
provide a return path so that current faults to blow a fuse.
On Mon, 22 Dec 2003 17:10:23 -0500, George Johnson wrote:
>created the ground connection for the L-C filter because the receiver had
>no ground reference (two prong plug) at all.
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