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N8973A Calibration - Newbie

Question asked by JBizkit on Jul 13, 2010
Latest reply on Jul 13, 2010 by Vladan
Hi all,

I am having trouble measuring noise figure and figured that I would start by looking first at the calibration.  I am getting a variation of ~8dB after measuring the device, this is after cal and without any loss compensation.  The device should be reading around 8dB, but I get 30ish.  I assume that the higher reading is due to the test setup not being taken into account during the calibration (cable, connector loss...etc), but I am not sure why I am getting such a large variation.  I calibrate simply by plugging the noise source into the input and pressing the calibrate button or should I be going through my test setup instead? 

I am measuring noise figure on mixer diodes using the following setup:

N8973A analzyer
N5183A signal gen
346B noise source
Waveguide fixturing
Preamp tuned to 30MHz

Test conditions:

LO 9.375GHz (1mW of power)
IF 30MHz  

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