Corn,
Sad to say, most the EMI we have measured in the lab from these CRTs is
coming thru the screen glass! There are some mesh screen covers that
attenuate some of it, but shielding of the case and leads is a good idea as
well. But, it is an artifact of the high voltage deflection against the
phosphors that sprays EMI out the front, and not much other than distance
from the radio will help it.
We actually decoded what was on the computer screen as a visual pattern by
picking up the RF a room away and applying it to a high frequency lab
oscilloscope.
Of course, the sync lack caused the picture to continuously roll, but you
could make out what the characters on the CRT had been.
The replacement of vacuum CRT technology with LCD matrix or other flat
screen types hopefully will ban this EMI source.
73,
Stuart K5KVH
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