solderless sma screw mounting RF causaliy problem

[john23]

Hello,I have a PNA which works till 120GHz I use a 1mm to 1.85mm adapter to measure till 67GHz 1.85 SMA.



I need to measure a differential lines.

At first i got low causality about 50% so i played with the connector screwed unscrewed tried wipe of some spots i saw on the ground pad.

Then i saw that the causality got to almost zero and i cant improve it back to the values before.

I tried to changes cables to shorter ones.

I dont know if my 1mm to 1.85mm screwed proprly to the PNA.

I dont know how to place properly the SMA and how much presure to put on the screws so it will work properly.

Any help?

photos attached.

Thanks.