Measurement Considerations; Power Handling - Keithley 7711 User Manual

:CARD
If no card is in slot <NRf>, then all of these commands will generate a -241 "hardware missing" error. If the card does not
support the feature or channels being queried, then 0 will be returned.
Unlike the Model 2700/2702, the Model 2750 SYST:CARD queries have the slot passed as a <NRf> following the query
(rather than incorporated into the command name). For compatibility with existing Model 2700/2702 software, the
Model 2750 also accepts SYST:CARD1 or SYST:CARD2 (not recommended for queries when developing new software).
Example: To query the maximum voltage allowed on the card in slot 3, send:
:SYST:CARD:VMAX? 3

Measurement considerations

Termination of unused connectors
To minimize noise within the system, terminate unused channels with 50Ω loads. If 50Ω loads are not available, terminating
unused connectors with a cable may also reduce noise within the system.

Power handling

The graph in Figure 7 shows the maximum amount of power per channel that can be routed using the Model 7711 or
Model 7712 while maintaining proper digital multimeter accuracy. Power levels of up to 10 watts at frequencies > 200MHz
can be used, but this may cause measurement errors. For example, routing 10 watts of power at 1GHz may cause the
Model 2700/2702 to have an additional 6µV offset uncertainty when measuring DC voltages. For the Model 2750, the
precision low level circuitry may cause uncertainty of 30µV. Moving the Model 7711/7712 to a higher number slot will reduce
this uncertainty.
Figure 7
Carry power (per channel) vs. frequency
12
10
8
6
4
2
0
10
Model 2750 commands only
200MHz
Additional DMM Uncertainty
500MHz
100
MHz
1000 3500
15