Marconi MkIII rack mounting power supply type BD630D.

A substantial rack mounting stabilised power supply for the Marconi MkIII camera channel. the main output is 250v DC at 1amp, plus 330v DC at 330mA. Additionally there is a negative voltage rail and a low voltage ~ 1.5v for the alignment coils. The focus supply is 75mA and is only suitable for cameras with the 3 inch I.O. tube. It is a conventional design with 5 double triodes ( type 6AS7 or 6080 ) in the main supply and one in the focus supply.

The 6 empty octal valve sockets are for the rectifiers, type 5R4-GY or equivalent.

The meter, type BD.642, to the left plugs into this PSU unit, and many other similar units. The rotary switch on the equipment selecting the voltage or current to be measured.
The meter is scaled 0-15 and 0-150 the button changing the range to the lower value.