A WW2 Power Supply Unit Type W7684

This was used in the CNY-2 HF Transmit/Receive Equipment

See the matching receiver


The PSU output is carried by a special connector (pins 1 to 16) which mates with a socket in the CNY-2 case. The unit is designed to work from either a mains supply 100/110/220/230/240/250 volt or from a 12 volt or 24 volt battery. Selection of the desired input is made by setting a 10-pin plug into either an "AC" or "DC" socket mounted on the top of the mains transformer (see below). Apart from the plug/socket and DC voltage setting a specific set of fuses must be fitted into a selection of holders and in addition the correct 4-pin vibrator, in this example for 24 volt operation, type NS/24 is fitted behind the front panel. HT is derived from a pair of selenium rectifiers connected as a full wave bridge, 4.5H choke L1, 8uF reservoir condensers C12/C13 and 8uF smoothing condensers C14/C15. There's a switch for selection low or full HT (this is primarily for enabling a reduction in battery drain and changes the level between 175 and 250 volts).


The valves in the CNY2 equipment use 6.3 volt heaters so its easy enough to wire pairs of these in series to run from 12 volts but not so easy to run from 24 volts so this is accomplished rather inefficiently by using ballast resistors.






 An 8-way switch on the power supply front panel permits checking the state of the CNY-2 as indicated on the label.

 And here's its circuit diagram



 Various views of the W7684 Power Supply Unit












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