Thanks for the many replies, too numerous to mention individually, in
regard to cleaning up my DEC-VT220.
(1) I have diconnected the keyboard with no improvement.
(2) I have tried a brute force AC line filter, in addition to
shortening the power cord, with, perhaps, a SLIGHT improvement.
At this point it seems fairly clear that the problem is radiation from
the cabinet and/or screen and the whole shielding thing seems like a
lot of work. Guess I'll look for an El Cheapo 386/286 (do they still exist?)
machine and see if I can't do better.
Again, many thanks.
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