We report the results of a search for a W′ boson produced in pp¯ collisions at a center-of-mass energy of 1.8 TeV using a 106   pb−1 data sample recorded by the Collider Detector at Fermilab. We observe no significant excess of events above background for a W′ boson decaying to a top and bottom quark pair. In a model where this boson would mediate interactions involving a massive right-handed neutrino (νR) and have standard model strength couplings, we use these data to exclude a W′ boson with mass between 225 and 536   GeV/c2 at 95% confidence level for MW′≫MνR and between 225 and 566   GeV/c2 at 95% confidence level for MW′