Radio Antenna Grounding:
The question arises, "On antique radios, is it permissible to connect the antenna ground terminal to the safety ground of a 3-prong AC receptacle? I say no because the safety ground is a poor RF ground, and there is the danger of 120VAC appearing on the safety ground. There is also the possibility of a lightning strike entering the safety ground.
A copper cold water pipe or a ground rod connected to the central ground node would be the correct method in my opinion.
Don't mess with B+!
(Signal Corps. Motto)