Scored an 8663A a few months ago and had not done more than a quick initial check out. Will be needing it soon, so over the last couple of days replaced all of the PS electrolytic caps and changed to a DC fan. Buttoned it back up and checked the output levels with the one power head (and meter) that has a current valid calibration. Specifications are +- 1 dBm for this range so I think a worst case error of .28 dBm and an average of the absolute error values of .0641 dBm is pretty respectable. From appearances this unit had been banged around quite a bit (thankfully, all damage is the the covers) and has been out of service for a while so, yet again, I am impressed with the engineering and build quality that went in to this generation of their products.
Now, a question: This piece is going to become a centerpiece of my personal working collection and I would very much welcome any suggestions from those familiar with it on things to watch for and, in general how to make the most of it: tips on care and utilization not found in the manuals, hidden "gotchas" and such.
TIA,
Hal