Royal naval communication transmitter's and receiver's 1950-1970 {approx} period.

Part 1 : Transmitters - REMEMBER?  R E F R E S H   IF  NECESSARY!

Note: I do not have pictures of the 696 {UHF transceiver}, the 689 {VHF transceiver} or the 692 {UHF transmitter, although it is virtually the same as the 693 shown}, so the block-diagrams will have to do.