I have a good old HP 8753C vector network analyser in my shack, however, I miss a proper SOLT calibration kit. Here is how I built my own calibration kit and made a model for the 8753C.
In the service manual of the HP 8753C, I read something about a cavity oscillator which is used in this instrument. Later, I read some article in the HP Journal, also about cavity oscillators. Time to build my own!