Posted for Peter.Sokolowski@t-online.de:

  Hello all,
 first thanks to all of you who have provided tips for my problem. Finally I
want to communicate the final solution with which I have solved my
interference problem.
 The solution is to shield the servo signal wires. Grounding of course only at
one end - works fine and no further reaction by the autopilot during
transmission at any frequency.
 Thanks again
 Peter (360 85%)