When using automatic control from PC then both the elevation and azimut is controlled (moved) at the same time. It seems that the Dell power adapter can not handle the current amp spike and turns off (overload protection I guess).
I have now return to using my 13.5 volt power supply.
I have been powering my Rot2Prog rotor controller for my RAS rotor with 13.5 volt. This means that the rotor turns slow. My 13.5 volt power supply also has a very high idle consumption of 10 watts.
I changed the power supply to a standard Dell power adapter – LA130PM121 19.5V 6.7A PA-1131-28D1 130W. It can be found very cheap. I just cut off the power plug and connected the wires from the Dell adapter to the Rot2Prog controller wires.
Now the turning goes MUCH faster! The Dell adapter also has a very low idle consumption – under 0.5 watt. So it can be connected all the time. What I can see there is no interference from the adapter on VHF and UHF.
I highly recommend using the Rot2Prog controller with an old computer adapter. Below is a short video of how fast it is turning.