If the sub-gap slope is negative or very large go into the Rx control window
and adjust either the
tuner while keeping a careful eye on both the Total power and SIS current Bargraphs.
The Total Power value will drop dramatically in most instances, but
the the SIS current will should the same or perhaps slightly increase. The
operating point is typically just before the SIS current degrades. At this point the SIS mixer gain is
reduced to slightly less than unity which provides a stable operating point for the mixer.
At this point either go back into the mode and study the pumped sub-gap slope on the scope (I/V display), or press the Slope button in the to obtain a numeric value.
Alternatively you can stay in the IV sweep mode, and gently adjust the E-plane (or alternatively the backshort) tuner until the slope changes to flat to slightly positive.
| Receiver Index | Rx Tuning Menu | Tuning Cookbook | Receiver Control | B-field Menu | I/V sweep Menu |
Web Page created and last updated on March 5, 2001, by Jacob W. Kooi