FCC regulations
The metal cabinet on the Kaypro II reduces the radiated electrical energy to a low level. The radiated interference on the weak, low-frequency television stations (channels 2 and 5) in my area was negligible.
The unit I tested did, however, have some conductive radiation through the power lines. My wireless intercom became noisy when the unit was turned on and really set up a racket when i used the disk drives. A filter in the line cord cured most of the problem. I checked with Nonlinear Systems, which confirmed that my evaluation unit did not have an internal line-filter installed. The company was aware that such a filter was needed and planned to install one on future production machines.
(Infoworld, October 18, 1982)