Yes I tried it with 20 nsec steps and 40 nsec pulse width and it showed the pulses slightly attenuated and you can see the phase shift move clearly. The funny thing is that I couldn't trigger these signals on my analog tektronics I kept fiddling with the knobs for 15 minutes. For some reason it triggered only on normal mode and not auto few days ago.
I have two DDS function generators, one from 0 to 2MHz and the othter from 0-5 MHZ, they are cheap modern type based on FPGA, I also have DDS module 0 - 40 MHz based on AD9850 but it needs a microcontroller circuit and LCD, which I built in the past but it doesn't have output amplifier and amplitude offset. But to be honest FPGA development boards are quite cheap and you can build any signal generator with them quite easily. I used the DCM of my FPGA and raised the frequency to 300MHz , both scopes went blind and I know that the FPGA board is still working because the push button switches and LEDs are still functional.
I guess you need a special probe for high frequency and you need impedance matching to display the high frequency waveform correctly. Do you know how to match the output of FPGA to the 50 ohm scope?
Mahmood