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Using a PNA-X in SMC mode as a multi output RF source for spurs

Question asked by SteveE. on Jan 13, 2014
Latest reply on Aug 5, 2014 by daras
Hope somebody out there can help me. 

I am attempting to use a 4 port 2 source N5242A PNA-X, an HP83640L and a E4440A PSA to replace the functionality of an ATE station that uses an E8362B PNA (single source two port,) three external sythesizers (hp836xx), an E4440A PSA (with Noise figure personality) and an HPIB bus switch to measure S Parameters, P1dB, PSAT, noise figure and mixer spurs on a two stage down converter, The current PNA SMC cal is configured 201 point swept RF in (port1), Swept LO1, fixed LO2 (not controlled) and a fixed IF out (port2). 

The current ATE has a HP83640 slaved to the PNA thru the bus switch with hardware triggering to generate the swept LO1, and a computer controlled 83640 (not controlled by the PNA) to generate the fixed LO2 to measure the S Parameters. 

P1dB, PSAT, Noise figure and mixer spurs are measured using the same 83640s under direct computer control as well as a third computer controlled 83640 as the RF input stimulus and the IF out switched to the E4440A PSA. 

I currently have the PNA-X set up in SMC operation with the internal source 1 providing the RF stimulus out of port 1, the second internal source providing the fixed LO2 out of port 3 and uses an 83640 as the slaved LO1 source. The PNA-X using an SMC cal to measure the SParameters, the Converter GCA app and Converter NF app to measure P1dB and NF respectively. PSAT is accomplished using the SMC mode with the RF input power such that it fully compresses the DUT and then PSAT is measured by way of reporting the swept DUT output power. Since I only have the one external synthesizer slaved to the PNA-X, I want to use the PNA-X/83640L "system" to provide the three CW power calibrated signals to the DUT for doing the CW spur measurements. I am thinking along the lines of having the SMC cal recalled and then resetting the swept frequency operation to fixed frequency on so that the signals will be the correct frequencies and powers for the CW spur search measurement. Sort of a three output synthesized source. I could then set the frequencies to the next set of values and take a new reading with the PSA. What are the SCPI commands that I need to send to the PNA-X, and in what order, to convert the swept SMC cal to a fixed CW operation without invalidating the power cals.
I can do it manually on the PNA-X but my attempts to redefine the mixer frequencies to CW from swept using VEE don't seem to work, the mixer setup reverts to a single stage and the RF freqs go back to the default values.

Thanks in advance for taking the time to read this and hopfully provide an answer.

Steve Estrin
Principle Test Engineer
Cobham San Jose  

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