Keysight Technologies P939 A Series User Manual page 34

quadrature point.
It's recommended that a Modulator Calibrate be redone after the unit has been on
for thirty minutes or when the unit temperature has stabilized. This will also be
required again if the surrounding conditions change. This can be done through the
SFP, or by toggling the unit's standby switch, or by cycling external power.
Notes:
1. Temperature changes will affect the performance output. This can be seen
in changes in magnitude of several dB with changes of ± 1 degree C.
2. If stabilization has not occurred after ten minutes, the unit will tune to a
quadrature set point.
3. It's recommended that after a thirty-minute warm up, another Modulator
Calibrate be done.
4. Measurements should only be made after the unit has had enough time to
warm up and has stabilized. A daily Modulator Calibrate is recommended.
5. The Calibrate function only works on firmware revisions 1.5.1.5,
2021/05/17:17:00:00 and above.
34 Keysight P939xA Streamline Customs User's Guide