R&S ZVA8 - Page 417

R&S ZVA Repairs
1177.5333.02 3.109 E-11
Coupler Directivity
The following is assumed:
 The generator and receiver sections of the reflectometer associated with the coupler unit are
OK.
 Perform a sweep from 10 MHz to 24 GHz, measure Ratio bx/ax Source Portx
 Screw the SHORT from the calibration kit to the port connector, save measured values (Data ->
Mem).
 Screw the OPEN from the calibration kit to the port connector, save measured values (More Mem :
Data -> Mem3).
 Screw the MATCH from the calibration kit to the port connector.
 Select User Def Math : linMag(Data) / ((linMag(Mem2) + linMag(Mem3)) / 2 : Math = User Def
 The trace gives the directivity.
Frequency range
Directivity
10 MHz to 12 GHz
< -15 dB
12 GHz to 24 GHz
< -10 dB
If the measured values are greater than the values stated in the table, the coupler unit must be
replaced.
Coupler unit: Port Matching
It is assumed that there is a functioning reflectometer in the instrument.
 Loosen cables W514 (GEN -> coupler unit), W515 (coupler unit -> MEAS) and W518 (coupler unit -
> REF) at both ends and unscrew at the coupler unit.
 Terminate the coupler unit input and coupler unit outputs with 3 SMA terminations.
 Connect test cable to a functioning instrument port and perform a 1-port calibration at the end of the
cable.
 Connect the end of the test cable to the port of the coupler unit under test and display the Sxx
magnitude on the screen.
Frequency range
Sxx dB
10 MHz to 12 GHz
< -14 dB
12 GHz to 20 GHz
< -10 dB
If the values in the table are exceeded, the coupler must be replaced.