[Arran]

Dan;
I'm trying to remember how these are wired on the larger Rogers models, but on the smaller sets there is a jumper on the speaker plug that disconnects the rectifier tube cathode/filament from the input filter cap. They may have pulled the same trick with a jumper on the interconnecting cable. I'm guessing that your power supply either came out of a lower end Rogers model, or out of a Majestic or Deforest Crosley model with the same dual chassis design, but without the chrome plate, of course you could strip it down and get the P.S supply chassis plated to match.
Regards
Arran