Where to begin?  Easy.  We'll start with the electrons and the electronics to master these little beasties aka the power supply.

There are several different supplies for both onboard and off-board purposes, but let's start with a top level block diagram:



The off-board components are:
Voltage Controlled Oscillator
Harmonic Multiplier
Detectors with LNAs

Onboard supplies are:
Analogue for: the DAC (LTC1668) and DAC transimpedence amplifier (OP37GPZ); range, Co and X amplifiers (OPA2228PAG4).