Their grandfather, John Shepard Senior and business partner Henry Norwell founded Shepard-Norwell, a Boston dry goods and retail store, in 1865.

It was installed on the fourth floor of the Boston store; personnel demonstrated radio equipment, sold ready-made sets, and let customers listen to music concerts from other stations.

[28] As far back as January 1923, Shepard's WNAC had already done a brief experiment with WEAF in New York, in which the two stations were linked for five minutes, proving that such a linkage could be achieved.

[31] These experiments were well received by the audience, and by the late 1920s, they became a regular part of the broadcasting schedule, ultimately leading to the creation of the Yankee Network.

[38] John Shepard III and his brother Robert founded the Yankee Network in a period of time from February 1929 to July 1930.

Its first affiliates, in addition to station WNAC in Boston and WEAN in Providence, were WNBH in New Bedford, WLBZ in Bangor, Maine, and WORC in Worcester.

At the height of its popularity, the network had affiliates in Massachusetts (Fall River, Lowell–Lawrence, New Bedford, Springfield), Connecticut (Bridgeport, Hartford, Waterbury), Rhode Island (Providence), New Hampshire (Manchester), and Maine (Bangor, Portland).

[41] The new facilities were also needed because of the growth of the Yankee Network; the Buckminster studios were more spacious, and thus more suitable for live broadcasts of radio dramas, or performances from big-band orchestras.

As one Boston Herald columnist observed, John Shepard III, who had gotten involved with radio as a hobby back in 1922, was now a dominant force in regional broadcasting.

[48] Shepard's next accomplishment was his involvement with the then-new technology of frequency modulation (FM) broadcasting, pioneered by inventor Edwin Howard Armstrong.

The Yankee Network's chief engineer, Paul DeMars, had heard a demonstration of Armstrong's innovation, and encouraged Shepard to invest in it.

Shepard agreed, pledging to spend the money necessary to build an FM broadcasting station that would serve greater Boston.

[49] Shepard saw FM as the solution to a common complaint of AM radio listeners: the signal often faded out unexpected, or noise from atmospheric interference made programs unlistenable.

[51] In mid-1939, Paul DeMars arranged a series of local demonstrations in Boston so that the press and the public could hear the benefits of Armstrong's invention.

[53] According to the Boston Post, it cost John Shepard III a quarter of a million dollars to build the new radio station.

[59] Then, in 1942, as a result of a Federal Communications Commission (FCC) ruling about how many stations one owner could have in the same city, Shepard had to relocate WAAB, from Boston to Worcester, Massachusetts.

[62] But then, in mid-December 1942, Shepard suddenly announced he had sold the Yankee Network to the General Tire and Rubber Company of Akron, Ohio; the move was surprising to most members of the broadcasting community.

[63] Under the agreement he negotiated, Shepard stayed on as president and general manager of the Yankee Network and its twenty-one affiliated stations for five years.