Hi Amos,
Try this link
My understanding is this: The 8565A was basically squeezing a 10 MHz-22GHz 141 specAn into one small box. It has a YTF in front of the mixer to remove harmonics and noise. It is a completely analog instrument with some early discreet logic for control.
The 8569a/b is basically the same rf section with the analog storage tube replaces with a low speed digital oscilloscope. This is done to allow the slow sweeps to be digitised with the slow ADC technology available at the time, while the higher frequencies required for zero span could bypass this for display on the tube as a cro.
It is not practical to convert an 8565a to and 8569 by replacing the display section. This was accomplished with the 8750 normalizer..
The rf section is slightly different with better dynamic range and noise floor - but not too different.
If the display or tube is shot, you could use the normalizer and a normal oscilloscope. Slow sweeps can be captured woth a pc sound card and there are some projects on the web.
Good luck
Tim
