I get a lot of enquiries for power supplies for the old JoeMeek VC3, MQ3 etc.
I’m now out of stock of the few I had kicking around, but you can get a suitable power supply from Maplin. Their part number is N57AT.
Note, this is an AC to AC power supply outputting 12 volts at 300+ milliamps.
A DC power supply might appear to work, but you will get horrible distortion and no phantom power. 😮