On the AFG320+ when both channels are set to the same signal channel to channel phase varies. Why?

On the AFG320+ when both channels are set to the same signal channel to channel phase varies. Why?

When starting from a default condition the two channels are independent, thus their phase is not fixed or constant. To achieve phase alignment between the two channels you need to perform the following steps:

1. Press Phase then Shift Both, this will lock the two channels into phase alignment.
2. Next press Shift Both again, this will unlock the two channels and leave them in phase alignment.
3. With Phase selected you may enter a phase number, +/-180 degrees, to adjust the phase to you needs.

If you change the frequency of one of the channels and then return to both being the same frequency. You will have to go through the above steps again to realign their phase.