ADF4351 settling time calculation using teh EVAL baords

Hello,

I am trying to evaluate the settling time of ADF-4351.

I have the evaluation board and here is how I am doing it:

- I am using the scope to look at the LD (Lock Detect) and the clock written to the ADF4351.the time between the last clock cycle and when the LD goes high will be my time t1

- Assume I am wring all the 5 registers, the time to do this will be t2.

Then my settling time (ts) will be:

ts = t1 + t2.

My questions are:

1- Is this approach correct and is there an easier way?

2- Whenever I connect the scope to the LD pin on the evaluation board, the LD led goes off. I do not know why..

Thanks,

Cherif