Interesting video! Didn't knew, those 8590A are build that noob friendly. I would have expected some wirebonded magic instead of discrete, soldered glass diodes.
Good work
Some pics of the 2-22GHz YTF-Mixer assembly of one of my 8566 spectrum analyzers. Mixer diode is under a extremely fine gold wire mesh in the assembly in the center, close to the blue blue blob.
The YIG filter is also in there, 3 YIG balls mounted onto ceramic rods for fine adjustment. In the back you can see the large magnet coil used for tuning those YIG filters. If you decide to take it apart, you need to mark the rotation of those magnet coils relative to the case, as the magnetic poles are slightly slanted, so they can be aligned to get the most homogeneous magnetic field between them.
Fry that and you're done. Instrument works perfectly now, btw. YTF tuning current vs frequency was misaligned, which caused the amplitude to drop at higher frequencies.
Anyone some pics of the 8568 1th mixer? Haven't had that one open, but would be quite curious, since that is my everyday use SA.