Percy Ronald Stevens was born at Napier, Hawke's Bay, on 10 April 1893, one of five children of Frederick Henry Stevens, a carpenter, and his wife, Mary Burton. Percy was apprenticed to a baker; he also worked as a fisherman. He then trained as a cycle mechanic, an occupation that allowed him to make use of his mechanical aptitude. Around 1908 he travelled to Gisborne where, by 1917, he had established his own motor and cycle business. This was later augmented and replaced by radio sales and repairs. On 12 April 1916 at Gisborne Percy Stevens married Edith Florence Watts. They were to have four children.
During the war Stevens, with two other enthusiasts, Ivan O'Meara and Bob Patty, carried out pioneering radio experimentation using a crystal set to listen for Morse signals. The government had an embargo on the private use of receiving or transmitting sets, and to avoid detection they hid their aerial in a tree each day, extending it at night. They picked up Morse signals from Western Samoa and after the war worked together to establish two-way short-wave links with amateurs worldwide. Early in 1923 Stevens and O'Meara established what is thought to have been the first two-way radio-telephone circuit in New Zealand.
Stevens, O'Meara and Patty were among the first to be granted one of the rare temporary permits which preceded the 1921 provisional permits. In 1923 they received one of the first broadcasting licences issued, as the Gisborne Radio Company, and established 2YM with Stevens as owner. Stevens had already been broadcasting concerts for several months.
2YM was first based at Stevens's home, but around 1928 harbour extensions forced him to move his business, the Atwater Kent Radio Company, from Wainui Road to Gladstone Road, and he shifted the station to his new premises. In 1926 the station's call signal had become 2ZM and two years later the station was relicensed as the Atwater Kent Radio Service to advertise the business. At that time O'Meara moved to the Bay of Plenty, and Patty later withdrew from the station, leaving Stevens as director, operator and owner.
Stevens recorded birdsong to play between items and organised the broadcast of 'storyettes' and live performances. He frequently ran and announced sessions himself. In later years he ran regular talent shows and children's sessions. At a time when most stations selected their news from the local paper, he actively collected news, albeit in a small-scale way, encouraging the public to contact him with items of interest. In July 1928 he participated in one of the earliest live international transmissions, broadcasting the Tom Heeney versus Gene Tunney boxing match from New York to crowds outside the station.
Although inspired to establish 2ZM because of his interest in technology, Stevens operated the station as a community service. He had an important local role in several crises: after the 1931 earthquake he broadcast news transmitted by amateurs in Hawke's Bay, and during the 1948 Gisborne flood 2ZM ran continuously for three days and nights broadcasting news, co-ordinating salvage operations and raising relief funds. A modest man, Stevens avoided praise for his efforts; it is said he once switched off the microphone to prevent an announcer acknowledging him publicly. He made no profit from 2ZM, as private stations were unable to advertise.
In 1936 the government began to nationalise broadcasting and by 1939 only 2ZM and one other station remained in private ownership. Stevens received a token subsidy towards running the station; the shortfall was covered by donations and on occasion by Stevens himself. The staff, which included Stan Vincent and Basty Nigro, worked voluntarily, as did the performers. In 1948 the station's call signal was changed to 2XM. Despite continued pressure to sell, Stevens resisted. His was the last individually owned private station in the country and he continued to direct and announce sessions until shortly before his death at Gisborne on 31 May 1963. He was survived by his wife, Edith, two sons and a daughter.