To stop the low phase noise operation and return to standard mode, un-check the Low 
Phase Noise checkbox on the clock panel of the Soft Front Panel. 
 
When the low phase noise mode is disabled, the instrument’s clock system is stopped, 
and a message window is displayed to inform the user that the external sample clock 
must be disconnected from the Low Phase Noise Clock Input of the front panel, as 
shown in the following figure.  Select Okay to return to standard mode, or select Cancel 
to stay in low phase noise mode.   
The external clock source must be disconnected from the Low Phase Noise Clock Input 
before continuing operation in standard mode.  The external clock source may remain 
connected to the Sample Clock Input.