The 1941 North American Regional Broadcasting Agreement moved WHDH to 850 kilocycles, and allowed the station to broadcast on a full-time basis. WHDH was able to increase power to 5,000 watts and go full-time, but not without protests from KOA, one of the dominant class A clear channel stations on 850 AM. For two years, from 1943 until 1945, WHDH was the local affiliate of the Blue Network, the former "NBC Blue", replacing WBZ as Blue affiliate; WHDH ceded the affiliation to WCOP after the Blue Network also chose to affiliate with Lawrence's WLAW (the facilities of which were subsequently sold to WNAC).