Stellar activity can be a source of radial velocity ( RV ) noise and can reproduce periodic RV variations similar to those produced by an exoplanet . We present the vigorous activity cycle in the primary of the visual binary H D 200466 , a system made of two almost identical solar-type stars with an apparent separation of 4.6 arcsec at a distance of 44 \pm 2  pc . High precision RV over more than a decade , adaptive optics ( AO ) images , and abundances have been obtained for both components . A linear trend in the RV is found for the secondary . We assumed that it is due to the binary orbit and once coupled with the astrometric data , it strongly constrains the orbital solution of the binary at high eccentricities ( e \sim 0.85 ) and quite small periastron of \sim 21  AU . If this orbital motion is subtracted from the primary radial velocity curve , a highly significant ( false alarm probability < 0.1 % ) period of about 1300 d is obtained , suggesting in a first analysis the presence of a giant planet , but it turned out to be due to the stellar activity cycle . Since our spectra do not include the Ca II resonance lines , we measured a chromospheric activity indicator based on the H _ { \alpha } line to study the correlation between activity cycles and long-term activity variations . While the bisector analysis of the line profile does not show a clear indication of activity , the correlation between the H _ { \alpha } line indicator and the RV measurements identify the presence of a strong activity cycle .