What range of stability should the PSA series show during cycle-to-cycle run of the Auto-Align process as far as amplitude? I have one that initially showed a variance of +5 / -12 dB and showed an align error. These I believe are usually only a few tenths of a dB.
I've narrowed problem to the subsystem "Align RF" portion and suspect there's an intermittent RF switch, other than the input attenuator. The amplitude reference input is from an HP 3335A.
As I was writing this, I ran the Align RF again and my -10 dBm input display dropped to - 53 dBm. I checked the attenuator again and the AC/DC switch - both OK. I don't have a service guide for this and would like to download if available.
Steve Reeves
I've narrowed problem to the subsystem "Align RF" portion and suspect there's an intermittent RF switch, other than the input attenuator. The amplitude reference input is from an HP 3335A.
As I was writing this, I ran the Align RF again and my -10 dBm input display dropped to - 53 dBm. I checked the attenuator again and the AC/DC switch - both OK. I don't have a service guide for this and would like to download if available.
Steve Reeves
In general the PSA is very stable with small variations in amplitude between alignments (tenths of dB or less). The exceptions to this is measurements made above 3 GHz with the YTF preselector. The YTF preselector does have some drift and hysteresis. For this reason, our specifications state to center the preselector before making a measurement. Nevertheless, even in the preselected bands, the PSA’s stability is still within couple dB. Consequently, if making measurements without preselector centering and if the preselector is off by greater than or equal to half the preselector bandwidth, then you can see wide differences in power measurements due to measured signal being on the skirt of the YTF filter. If you are seeing other large variations in power measurements, then you could have a bad mechanical attenuator step or other instrument failure, for which we recommend sending in the instrument for repair at an Agilent Service Center.
Regards -