W1XPW's conversion to FM was reported to have been completed as of May 13, 1939, with the station now operating with 1,000 watts on 43.4 MHz. Following an irregular series of test transmissions, the station inaugurated regular programming on October 2, with an initial schedule of 2 to 10 p.m. daily. W1XPW was the third FM station to broadcast on a regular schedule, after Edwin Armstrong's W2XMN in Alpine, New Jersey, and the Yankee Network's W1XOJ in Massachusetts. However, W2XMN was unaffiliated with any AM stations, and W1XOJ was owned by the Yankee radio network, so station publicity referred to W1XPW as the "first frequency-modulated outlet to be built by an independently-owned commercial broadcasting station" (WDRC). On January 4, 1940 W1XPW participated in the first demonstration of an FM over-the-air inter-city relay, which originated in Yonkers, New York, was received and relayed in turn to W1XPW by Armstrong's W2XMN in Alpine, then further relayed to W1XOJ in Massachusetts.