[Arran]

 Someone has a death wish, do not work on any AC/DC set whilst standing on a concrete floor with bare feet, no wonder why you were getting a tingle from the set. I found out about not grounding an AC/DC the hard way, and this was with one that had the chassis connected through a capacitor, but the radio had a proper antenna coil with what they used to call a "Hank Wire" antenna. The "Hank Wire" antennas used to consist of yards of a light weight stranded wire, almost like Litz wire, wound around a flat cardboard spool, which you would unwind across the room, naturally this set had it clipped down to maybe 2'.
 In any event I was playing with the set with the chassis out on the floor, put my fingers on the antenna wire, made the set play louder. So I put the antenna wire on the metal heat register to try it as an antenna, made a bunch of nasty noises and a hum come out of the speaker, register and furnace ducts were obviously grounded or close to ground potential. Then I went back to holding the antenna wire with my fingers, whilst I was sitting next to it, well I must have leaned back with my arm and put my palm on the heat register, ZAAAAPP! So I found out why you do not connect a ground to an AC/DC radio, the hard way!
Regards
Arran