Remove Hum from AA5

[Reece]

It's possible to make a hot chassis or "semi-hot" chassis radio safe once it's in the case. Ones from the late fifties and the sixties were made this way with no hot exposed metal. The safety of older sets can be improved with some ingenuity. For example, steel underchassis screws can be replaced with nylon ones which are plenty strong for most table radios. Backs can be provided that ventilate adequately yet keep fingers out.