An adapter alignment device, that can be added on the coaxial RF connectors of instruments, especially slide screw impedance tuners, aligns and guides precisely and repeat ably the male and female adapters into each-other. This leaves the internal center conductors of the tuner slabline, which are attached to the connectors and to external manually handled cables, intact; this is crucial for all instruments, most of all electro-mechanical impedance tuners, where data generated by previous calibrations are used in later measurement and where any other type of numeric adapter error correction or error model is impossible.