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ENA E5071C - issue with Unknown thru cal

Question asked by mirek on Dec 12, 2017
Latest reply on Dec 13, 2017 by mirek

I am having issue with full 2 port cal with unknown thru on ENA E5071C.

I am getting periodic ripple across wide band in Return Loss measurement.

That only happen if I use mechanical cal kit in Unknow Thru, however I do not see that in Thru/delay.

If I use Ecal (I see that now it have Unknown ON/OFF function), with Unknown OFF the return loss is smove, with Unknow ON it also show some ripple (smaller than from mechanical calkit). 

I use latest firmware 11.34. I also downgrade the firmware to 11.02, similar behavior.

I first suspect the the VNA have some issue, however single port calibrations show smooth return loss.

For Unknown Thru I set adapter delay to 81ps (measure with port extension on PNA-X).

For whatever reason if I set that delay to  Zero ps it look like there is not much effect on the calibration. 

The cal kit that I used is 85052D ( just come from annual calibration) the Ecal N4433A.

 

 

Somebody need to look in that.

 

Regards,

 

Mirekl  

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