The HP 8566B is the gold standard of vintage spectrum analyzers. It covers an enormous 100 Hz to 22 GHz band (and weighs a ton). Unfortunately, the HP 8444A tracking generator which I previously used with the HP 8568B (https://www.youtube.com/watch?v=_yZOW_aABlk) does not work with the 8566B. But here is how to modify an analog oscillator plug-in from an 8530B sweeper to make a baseband (up to 2.5 GHz) tracking generator for the 8566B.