Kwong explained the operation principle of an YIG tuned oscillator and demonstrated the tuning characteristics:
I was going through some of the components I accumulated over the years and stumbled upon a Hewlett Packard YIG tuned oscillator (part number 5086-7023) that I bought a while back. This YIG oscillator was made for a frequency extension module for the HP 8660C synthesized signal generator and has a tunable range of between 2.7 to 4.2 GHz.
More details on Kerry Wong’s blog.
Check out the video after the break.