Shortages of the special multi-voltage dry battery used by the 48 Set were such that NZ developed a special vibrator power supply unit permitting the set to run off a locally made battery made up of size D dry cells. The construction permitted the vibrator unit to fit below the Transmitter unit and battery pack to be enclosed in the regular battery holder of the 48 Set. The regular set on/off switch was locked on by a bracket and the set turned on by means of a switch connected to the vibrator unit and mounted in the hole normally filled by a rubber bung on the front of the battery compartment. The unit seems to have worked reasonably well but added to the weight. of the set.