That's what I get for trying to google and not think.Is the power supply not drawn at the bottom of the schematic? It's a B+ of 500V using a PWR45 Trans.
What I know about power supplies could be written on the back of a postage stamp. I'm pretty much the newest newbie.
I think Forty2wo (John S.) over in the Group Build Forum is going to build the DRD300b. John is a real good guys and helped us with the preamp build; he knows his stuff and might be worth pinging.....Colin