R&S ZVA8 - Page 422

Repairs R&S ZVA
1177.5333.02 3.114 E-11
Coupler Directivity
The following is assumed:
 The generator and receiver sections of the reflectometer associated with the coupler are OK.
 Perform a sweep from 10 MHz to 40 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 20 GHz
< -14 dB
20 GHz to 35 GHz
< -10 dB
35 GHz to 40 GHz
< -9 dB
ZVA50 only
35 GHz to 40 GHz
< -8 dB
ZVA50 only
40 GHz to 50 GHz
< -6 dB
If the measured values are more than 2 dB greater than the values stated in the table, the coupler must
be replaced.
Coupler Port Matching
It is assumed that there is a functioning reflectometer in the instrument.
 Loosen cables W514A (GEN -> coupler), W515A (coupler -> MEAS) and W518A (coupler -> REF)
at both ends and unscrew at the coupler.
 Terminate the coupler input and coupler outputs with three K-terminations (three V-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 under test and display the Sxx
magnitude on the screen.
Frequency range
Sxx dB
10 MHz to 5GHz
< -20 dB
5 GHz to 20 GHz
< -15 dB
20 GHz to 30 GHz
< -12 dB
30 GHz to 40 GHz
< -11 dB
ZVA50 only
40 GHz to 50 GHz
< -10 dB
If the measured values are more than 2 dB greater than the values stated in the table, the coupler must
be replaced.