FM Noise....?

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sfcillari
Posts: 51
Joined: Sat Apr 28, 2018 3:55 pm

FM Noise....?

Post by sfcillari » Sun Sep 20, 2015 10:30 am

Hi All,
I was testing a mmic amp and used the signal generator option as an rf source, this worked all fine. Then I listened to the carrier on a fm tuner. I was amazed about the high level of noise it produced. It sounds like the vco is  modulated by white noise. Disconnected the amp but same result. Then I swapped plo3 with plo1, same result and it is even worse.  Hooked up the tracking generator output to the msa input. Phase noise is not the best. Maybe an addition of phase of plo3 and plo1? Can't find the cause of the fm noise. Powersupply is clean and all the voltages are okay.Could anyone do the same test?  Set tracking gen to some fm radio frequency and listen to the carrier. 
Btw I'm using zcomm vco's.....
regards,
Simon

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