HI jpb. At the time I took the pictures, the unit was about 30 h online.
The ATDC is already active, which only happens after 24h of calculation time. The frequency of 10 MHz +/-2mHz always jumps.
Regards. Jörg
Thank you Jörg.
I'll have to check mine when I get the chance. I only checked mine over long gates where its average frequency is very good. If these jumps are a feature then perhaps we need to phase lock a second OCXO to it with a loop time constant of 100 seconds or so.
Looking at your plots, it looks as if it is the result of the LSB of the DAC controlling the OCXO - but doing a quick calculation:
the tuning on the 8663 is 0.3 ppm over 10V (according to the datasheet). 2mHz is 2 x 10^-3/10^7 = 2 x 10^-10
2 x 10^-10/3x10^-7 = 1/1,500 which is only about 11 bits, while I'd assume at least 16bit DAC which should give a resolution of under 50 microHertz so it can't be a resolution thing (unless they only use around 11 bits!)