The cable of my servo is much thicker than the cable of the Quark. Can I use this servo or the Quark only suitable for micro servos?

The five thin wires entering the gyro are control signals and power supply for the gyro electronics only. The servo is not powered through these thin cables. Instead we use 22 AWG thick cables to loop power from the rudder plug directly to the servo plug. These thicker wires (highlighted in red and brown in the illustration below) can carry sufficient current for all modern digital and brushless tail servos.