Let's assume I have two signal generators coupled via the 10 MHz reference. This means that their phase is locked and constant. However, will the phase change if I adjust the attenuation of the generators, i.e. is the attenuator's phase internally compensated? And if so, is there any way to achieve a constant phase even though the output power is varied? Thank you for your answer!
Actually the two generators aren't actually phase-locked, they're frequency locked. The phase of the output signals are likely to be different. Any changes you make to settings can shift the phase of the output of one generator in relation to the other. What you're looking for is probably phase coherent outputs. Here's a link to a description of phase coherency using Keysight equipment.
Thank you for your answer! I'm indeed looking for a locked phase, i.e. a phase which is constant with respect to the 10MHz reference and which is independent of attenuators and other function blocks in the internal signal path. I did some more reading and found out that the PNA-X (two sources) should be able to control its phase by using a reference receiver (details here). Is the phase control still available, if frequency extenders are used?
Actually the two generators aren't actually phase-locked, they're frequency locked. The phase of the output signals are likely to be different. Any changes you make to settings can shift the phase of the output of one generator in relation to the other. What you're looking for is probably phase coherent outputs. Here's a link to a description of phase coherency using Keysight equipment.