In a color display tube including an envelope, a display screen, an electron gun system for producing and focusing a plurality of electron beams directed at the display screen, and coils for deflecting the beams, convergence of the beams independently of focusing is effected by a helically wound resistive element disposed in the envelope between the electron gun system and the deflection coils. The element surrounds the electron beams and is dimensioned such that, when predetermined potentials are applied thereto, a potential gradient is produced along its length which establishes a relatively large diameter, strong convergence lens through which the beams pass.