I've measured the TX phase noise performance at 2600MHz ( LO 2570MHz , 3dBFS SSB CW 30MHz ) ,
and i seem to begetting poor results at close in offset (10Hz to be exact).
At 10Hz , my reference is -109dBC/Hz. For the 2570MHz LO , the phase noise should be -109+20log10(2570/30) ~ -70dBC/Hz.
I'm getting a phase noise of about -45dBC/Hz. This is a big difference from the theoretical calculation. Could you explain this?
My reference is a 5dBm 30.72MHz clock, generated using a signal generator.
Below is the reference phase noise performence -
This is the phase noise measured at 2600MHz:
The profile i was using:
Thanks in advance,