While many radios may have negative of the supply tied to their chassis,
if you also tied the negative at the supply to its chassis, you have
then created a ground loop.
That is what had happened at the club station incident.
By the way, the club station grounding internal and external, had been
performed by a electrical generating plant and HV engineer. (A ground
loop can sneak up on anyone.)
Also, perhaps I did not make clear, that the tower was not only grounded
to earth rods, but bonded to the main building AC ground ten feet away,
and at that point, also to a water pipe ground of a metal water line
entering the building just below the utilities.
Chassis and AC/earth Grounding the negative ONLY at the radio prevents a
local ground loop,
such a loop is where lightning surge mischief can cause real damage.
Luckily, the burned out board trace was able to be replaced with a
copper shunt, and the operation of the radio was back to normal.
-Stuart Rohre
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