HP 85108, System Manual, Page: 63 / 136

instrumen t state. The same TTL pulse train pro vides the pulse mo dulation input to the RF
source and to the HP 8510 rear panel TRIGGER IN connector.
Please note that for in ternal triggering, a BNC short circuit is connected to the TRIGGER IN
connector. When the pulse generator is connected to TRIGGER IN, mov e the BNC short
to the SWEEP IN 0 to 10V connector. Otherwise, signals on the sw eep in line could aect
triggering.
Figure 3-22. External Control of PRP and Duty Cycle
Sync hronization is assured b ecause time equals zero seconds for eac h measuremen t cycle
is dened as the rst falling edge of the trigger input after stop sw eep is ready (high).
Figure 3-22 b sho ws connection of an external pulse mo dulator instead of the in ternal
mo dulator in the RF source.
Figure 3-23 sho ws results using this pulse mo dulation and triggering metho d when the
pulse mo dulation input to the RF source is a con tinuous train of 10 microseconds PRP , 50
Operation 3-27