924
Input/Output
Input Z Correction
Sets the input impedance for unit conversions. This affects the results when the y-axis unit is voltage or
current units (dBmV, dBµV , dBµA, V, A), but not when it is power units (dBm, W). The impedance you
select is for computational purposes only, since the actual impedance is set by internal hardware to 50
ohms. Setting the computational input impedance to 75 ohms is useful when using a 75 ohm to 50 ohm
adapter to measure a 75 ohm device on an test set with a 50 ohm input impedance.
There are a variety ways to make 50 to 75 ohm transitions, such as impedance transformers or minimum
loss pads. The choice of the solution that is best for your measurement situation requires balancing the
amount of loss that you can tolerate with the amount of measurement frequency range that you need. If
you are using one of these pads/adaptors with the Input Z Corr function, you might also want to use the
Ext Gain key. This function is used to set a correction value to compensate for the gain (loss) through
your pad. This correction factor is applied to the displayed measurement values.
Readback: The RF input port, RF coupling, and current input impedance settings appear
on this key as:
"XX, YY, ZZ" where
XX is RF, RF2, RFIO1, RFIO2, depending on what input is selected (only
appears on test sets with multiple RF inputs)
YY is AC or DC
ZZ is 50 or 75
Initial S/W Revision: Prior to A.02.00
Key Path: Input/Output, RF Input
Remote Command: [:SENSe]:CORRection:IMPedance[:INPut][:MAGNitude] 50|75
[:SENSe]:CORRection:IMPedance[:INPut][:MAGNitude]?
Example: CORR:IMP 75 sets the input impedance correction to 75 ohms.
CORR:IMP?
Couplings: When the main RF Input is selected, the Input Z Correction will automatically
change to 50 ohms. You may then change it to whatever is desired.
Preset: This is unaffected by a Preset but is set to 50 ohms on a "Restore Input/Output
Defaults" or "Restore System Defaults->All"
Some instruments/options may have 75 ohms available.
State Saved: Saved in instrument state
Readback: 50 Ω or 75 Ω. Current setting reads back to the RF key.
Initial S/W Revision: Prior to A.02.00