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How does one use a 75 Ohm VNA to make measurements in 50 Ohms?

Question asked by drkirkby on Dec 18, 2012
Latest reply on Dec 19, 2012 by drkirkby
I know someone who has got a 8751A VNA with an 87511B 75 Ohm test set. He has no need for 75 Ohms, and wants to use this as a 50 Ohm VNA. What is involved in doing this? 

He was under the impression the 75 Ohm test set was basically a 50 Ohm test set with minimum loss pads inside, so thought it would be simple to just remove them, but now I think he has concluded it is not as simple as that. The 87511A is 50 Ohms, but the 87511B he has is 75 Ohms. 

Should one just put minimum loss pads externally to convert the 75 Ohms of the test set, set the system impedance in the VNA to be 50 Ohms, then use a 50 Ohm calibration kit? Is there anything else one needs to do? 


Dave  

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