Canadian Centurion tanks intercom system?

[David Herbert]

JD9 is the 9th variant of a "junction distribution" box. Basically a router for the radios and intercom (IC) system.
RBJ is the "rotary base junction" which is the unit in the bottom of the turret which connects the electrical services including radio and intercom between the rotating turret and the stationary hull. It contains a lot of copper slip rings and carbon brushes and is the limiting factor of how many radio functions can be routed between the hull and the turret. In WW2 British tanks that had hydraulic turret traverse powered from an engine driven pump the hydraulic circuit went via the RBJ too, making it even more complicated.

David