Tektronix CSA8000B - Manual (Page 118)

Triggering
3- 44 CSA8000B & TDS8000B User Manual
Trigger Source Connectors. External triggers can be connected to either the
Trigger DIRECT or Trigger PRESCALE connectors on the front panel (see
Figure 3--13):
H Signals connected to the PRESCALE connector are divided by eight and
then fed to the trigger circuits.
H Signals connected to the DIRECT connector are fed directly to the trigger
circuitry. The signal is DC coupled and can be up to 3.0 GHz.
When using a given trigger source, you should disconnect any other trigger
source from the front panel to ensure specified performance. Specifically:
H Do not connect a signal to the Trigger Direct or Trigger Prescale front-panel
connector unless you’ve selected that input as the trigger source.
H Do not connect a signal to the External 10 MHz Reference front-panel
connector unless you have selected that input as the timebase mode in the
Horizontal setup dialog box.
Probe-to-Trigger Source Connection. You can connect probes, such as the P6207
and P6209, to the Trigger DIRECT input connector of the instrument. Observe
all static precautions outlined in the documentation for the probe you choose
while following these steps:
H Connect the probe-power connector to the TEKPROBE-SMA compatible
probe (Level 1 or 2 only).
H Connect the probe signal connector (probe must have an SMA connector) to
the Trigger DIRECT source input (not the PRESCALE source input).
H Connect the probe input to the signal that is to supply the trigger source.
The probe you attach preconditions the trigger signal for its input just as other
probes do for the vertical inputs. More specifically, a probe attached to the Trigger
DIRECT input may affect trigger-level range, resolution, and units as follows:
H Trigger-level units will match those of the probe.
H The trigger level for probes that have offset control is adjusted by changing
the offset of the connected probe and is limited by the range, resolution, and
offset characteristics of the probe.
H When a connected probe is removed and a different probe installed, the
instrument attempts to keep the same absolute trigger level as the current
trigger-level setting.
Note that the probe parameters (range, resolution, offset scale, and units) that are
relevant to the trigger circuit affect the Trigger Level control.