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Problem in receiver of PNA-X N5242A

Question asked by rvv on Dec 22, 2013
Latest reply on Jan 1, 2014 by Dr_joel
Hii.. I am using PNA-X N5242A for my measurement. I am using Trace S21 for my measurement & Receiver B of PNA-X for performing source power calibration in Pulse mode before performing the test on DUT.

Input Power of DUT  *0dBm*

Output Power of DUT *53 dBm*

I am using 50 dB attenuators at the output of DUT to reduce the power & my cable loss is around 5 dB. So I am getting less than 0dBm power at port 2 of PNA.

I was performing test after source power calibration from last 1 month & I was getting desired results everytime. 


suddenly on one day, When I performed source power calibration, *PNA shows source pow calibration failed*. *So I check generated Power @ R1 (receiver), it shows -25dBm eventhough I was generating 0dBm power from Port1.*
*Then I connect Port 1 & Port 2 through a cable & check the Power level @ receiver B, it also shows -25dBm.*

*but PNA was generating exact 0dBm @ port 1 when I check through PPM*. 

then I call agilent person to check the PNA reciever, after checking the PNA he told that receiver A & B has gone bad because you fed high power then Max. permissible power level. 

*I am not able to understand how it can happen, because I am using 50 dB pad at the output of DUT. or if it happen then only receiver B should go bad, because I am using S21 trace.*

*Is there any other reason by which receiver A & B can go bad?*

I need help to diagnose the reason.