It's been chilly out again, and the 8568/85662 has been running stable since last night without any sweep-stopping, so I took the opportunity to work on the TG some more. I took some screen shots to record the dynamic range and look for adequate isolation. Only one came out legible after freehand shooting of the upside down display. It's at
/g/HP-Agilent-Keysight-equipment/photo/78668/0?p=Name,,8568,20,1,0,0in a new photo album called "8568 TG project." I think I managed to get the image right side up, at least on my PC. My apologies for the poor photography or if it shows upside down.
This one shows the full ~0 to 1500 MHz span, at IF and video bandwidths low enough to get near the noise floor of the 8568 - each sweep took 500 seconds. The top A trace is the TG output near 0 dBm reference level, while the bottom one is the stored B trace maximum hold values, with the TG in its "RF OFF" mode. It exhibits better than 90 dB dynamic range between the states. The small spurious signals and ripples in the noise floor are due to leakage through the coaxial relays that rout the center frequency mixer output and amplifier output signals within the TG. When the cable from the TG out to the SA is disconnected, these disappear, leaving just the SA's noise floor. Other experiments confirm that the TG is virtually invisible to the SA, due to good isolation of all the LO signals, and proper containment of the TG's internal operating signals.
Ed
