I recently acquired an 8596E which performs flawlessly in band 0.
At the band 1 transition, an additional loss of 27dB is seen.
I've fed in a source toggling between 2.9GHz and 3.0GHz which is in band 0 and 1. The band 0 amplitude is spot on while the band 1 amplitude is 27dB down. The same can be seen in the comb signal.
Here's the odd thing (lacking knowledge of the internal cal, however). If I run the YTF cal, as each spur of the comb is used for the cal, the cal waveform shows NO drop as the frequency enters band 1.
How can this be? Since the cal uses the actual analyzer input, wouldn't that rule out the SYTF or mixer as problems?
What would cause this huge attenuation to appear in actual use but not in cal.
The unit occasionally cannot complete YTF cal and most times fails mixer bias cal, no doubt due to this band 1 loss.
Thank you for any light you can shed on this problem.
Den
At the band 1 transition, an additional loss of 27dB is seen.
I've fed in a source toggling between 2.9GHz and 3.0GHz which is in band 0 and 1. The band 0 amplitude is spot on while the band 1 amplitude is 27dB down. The same can be seen in the comb signal.
Here's the odd thing (lacking knowledge of the internal cal, however). If I run the YTF cal, as each spur of the comb is used for the cal, the cal waveform shows NO drop as the frequency enters band 1.
How can this be? Since the cal uses the actual analyzer input, wouldn't that rule out the SYTF or mixer as problems?
What would cause this huge attenuation to appear in actual use but not in cal.
The unit occasionally cannot complete YTF cal and most times fails mixer bias cal, no doubt due to this band 1 loss.
Thank you for any light you can shed on this problem.
Den
I discovered that the 100MHz comb was off by 600Hz (spec is +/- 40) so I adjusted to within a few Hz.
This made no difference as the unit still had a problem with YTF cal and Mixer Bias cal, both near 11 - 12 GHz.
It looks like if the 27dB of loss at 2.9xx GHz went away, these cals would all pass.
When you run the YTF cal, the "gas gauge" at the screen lower edge, which I presume is related to the drive level on the YTF, goes all the way to screen center at the 11 - 12 GHz region.
So the problem remains ... what is the cause of the 27dB loss and why doesn't this show when you watch the YTF cal progress?
Den