Re: Adding earth lead to vintage radio.
I'm afraid the statement that "AC only set chassis can be earthed, AC/DC set chassis can't" is a bit simplistic. There are sets such as the Kolster Brandes toaster radio KB10 which have a heater transformer and "E" range valves and are AC only, but are still live chassis.
Your best option is to check the service manual (or get others here to do it for you) and/or measure the resistance between the chassis and both sides of the mains. If the chassis is isolated from the mains, then adding an earth connection with a 3-core mains cable can add safety if an insulation fault occurs.
If the chassis is not isolated from the mains, then you need to rely on very old insulation for safety. Making sure the chassis is connected to mains neutral not mains live and adding an RCD, either in the house consumer unit or in the radio mains plug, is a good idea.
Stuart
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