Abstract: A deflection unit for a color television display tube comprising line and frame deflection coils and a magnet core cooperating with said coils can be manufactured by placing the deflection coils and the magnet core around the part of the transition neck-cone of a color display tube in such manner that the deflection coils engage or substantially engage the tube, which display tube comprises an adjusted color purity magnet, after which the tube is adjusted so as to be color pure by moving the magnet core along the axis of the tube, after which, if desired, the magnet core is moved in known manner in a plane perpendicular to the tube axis so as to remove convergence errors and the magnet core and the coils are then connected together to form the deflection unit.